Leaking Pool: Find and Fix Pool Leaks

Pool leaks can be aggravating, especially when you don’t see any leakage, and don’t know where to start. This post, originally from 2018 – is all new for 2020!

How do you know if your pool is leaking? On a hot day, evaporation from a swimming pool can account for 1/4″ of pool water per day, and a good backwashing may use up to an inch of pool water. And maybe your backwash line is leaking water or a loose plumbing fitting on the pump has a steady stream?

Splashout may be a noticeable amount, if you have a lot of pool activity, but not normally. After accounting for these unavoidable leaks, if you still think your pool is leaking – read on, my friend.

Is your Pool Leaking?

To remove evaporation from the equation, you can perform a Bucket Test on your pool. Place a 5 gallon bucket on the first step of your pool, in a swimout, or on the top step of your ladder. Fill the bucket half-full of water and mark the water level with a piece of electrical tape (or use a permanent marker) on the inside of the bucket. With a second piece of electrical tape, mark the pool water level on the outside of the bucket. Avoid backwashing and splashout for 24 hours, and compare the two marked measurements.

The water lost from the bucket will only be evaporation, but the water lost from the pool is evaporation, plus (?) any other water loss. If there is a noticeable difference between the two, you can begin to locate the leak in your pool.

How to Find Leaks in your Pool

Leak detection in swimming pools is a step-by-step process of elimination among 4 main areas; the Pool Shell, Pool Lights, Pool Plumbing and the Pool Equipment. Let’s dive right in, shall we?

To find a pool leak, the first place to inspect is around your filter and pump. Do you notice any water spots or damp areas there? If so, try to trace back where the water is coming from. Very often, it will be a connection on one of the pipes in this particular area. You may need to turn on the pump for a while and observe it to see if any leaks develop while everything is running. However, a small drip on the pump or filter will not amount to much, and is likely not noticeable in the pool level.

In order to determine whether or not the leak in the pool is in the plumbing or in the shell of the pool, you would isolate the plumbing. This means to plug all the holes in the pool. Plug the skimmer and the return fittings, cleaner fittings, vacuum lines, main drain (if possible) with expandable freeze plugs or threaded plugs.

If no obvious leaks can be found in the plumbing, then perhaps the leak is in the shell of the pool itself. If your pool is gunite, your plaster whitecoat is the water proof layer over top of concrete. Much tougher than a vinyl liner.

Leaks in your Pool Shell

Vinyl pools have the most vulnerabilities in this area, with the potential for small tears in the vinyl, seam separations, or leaking around the cuts that were purposely made for the light, steps, skimmer, drains and wall returns.

Concrete pools can leak through a crack in the shell, most commonly in the tile line, or through small voids surrounding pipes that come through the wall, or the very common skimmer leak, at the interface of the plastic skimmer and concrete pool wall.

Fiberglass pools can also leak through a crack in the shell like a concrete pool, or leaks in the skimmer, return, drain or light faceplates.

pool winterization plugs - also used for leak detection in pools

To find or to rule out leaks in the pool shell, plug all of the plumbing lines – skimmer, main drain, returns. You can use rubber or threaded plugs – the kind used for winterizing. Shut the pump off at the breaker, so it won’t turn on while the lines are plugged. You may also want to shock the pool beforehand, as you might need to keep the pump off for a few days, if it keeps dropping. Raise the water level to the normal level before beginning this test, to prevent confusion – when the water has already stabilized at the lowest level.

Many times, if the leak is large enough, it will quickly drop to, and stabilize at the problem area. This may be right at the bottom of the skimmer, or just beneath the returns or at the pool light. If pool water level continues to drop with all of the lines plugged, you can rule out the underground plumbing (your worst fear). If however, the leak stops when you plug the pipes and shut off the pump, jump ahead to plumbing and equipment pool leaks.

When it seems that the water level has stabilized (remember that evaporation will continue unless you cover the pool completely with a solar blanket, and you will need to subtract any rainfall amounts), you can begin to inspect the waterline area closely.

Anderson Dye Testing Syringe for pool leak testing

When your pool shell or vinyl liner has a leak, usually you will find small bits of debris that have been sucked into the crack or rip in vinyl. To confirm a leak in a suspected area, use food coloring or a dye syringe to dye test the area.

Dye testing is done with the pump off, to reduce currents. Squirt a small amount of pool test dye near the area to see if it moves towards and gets sucked out of a hole. Wear a mask or goggles to see the action clearly.

Leaks in the Pool Skimmer

One of the most common areas for leaks on an in-ground pool, leaks can occur inside the skimmer body, or on the sidewalls of the skimmer, usually from winter freeze damage or excessive ground movement. Aboveground pool skimmers are often replaced entirely when leaking occurs, due to their low cost.

vinyl skimmer gaskets, screws and faceplates

On vinyl liner pools, the faceplate and gasket are always the first suspects and can be dye tested, as described above. Rust on the skimmer faceplate or vinyl liner can be a sign of a leak, causing rust to form on the pool walls, which can damage the liner and walls.

If the wall area around the skimmer is rotted or rusted through you can use JB Weld to resurface a rusted wall, or you can use sheet metal to reinforce the area. Glue it and screw it, and then tape the edges with duct tape.

Sometimes a vinyl pool skimmer leak is just a loose faceplate, check that all screws are [very] tight. Install vinyl pool faceplates very tightly, using a #3 Phillips head until it squeaks and creaks!

Vinyl pool wall and floor fittings all have two gaskets, one under the liner and one above the liner. Replacing both faceplate gaskets is important, and be sure to use only OEM factory stainless steel faceplate screws if you need replacements. Other screws may not tighten properly and can rust.

showing areas to check for leaks on a pool skimmer

On concrete pools, look inside the skimmer, to the point where the pool tile meets the front of the plastic skimmer. Inspect for cracks and debris stuck in the cracks. Dye testing will confirm the leak, often found on one or more of the three sides shown in the picture, directly where the concrete pool meets the plastic skimmer, which expand and contract at different rates, with fluctuating temperatures.

You can also use food coloring or your pH reagent for dye testing suspected leaks. If using a test reagent from your test kit, be sure not to suck in any water into the bottle, which will dilute the reagent and give false test results.

pool-putty for pool leaks

Cracks in the skimmer body (below the lid) can be repaired with an underwater epoxy mix, commonly sold as Pool Putty. This can also be used on the front 3 sides of the skimmer, where it mates with the concrete pool to fill in the voids and cracks.

To use Pool Putty, chip out all loose or cracked material, mix equal parts of resin and hardener with a bit of pool water until a uniform color. Then roll it into a ‘snake’, and push the putty in place. It can be used underwater or above water.

EZ Patch 1 FS pool plaster mix shown in 3lb and 10 lb sizes

A second method for fixing inground concrete pool skimmer leaks is to pack in new plaster at the interface of the plastic skimmer and the concrete pool wall, or tile really. Chip out old loose plaster where the tile ends and the plastic begins, and pack in new pool plaster mix to seal it up again. Plaster mix is easy to work with, just add water and stir to a spreadable consistency and place with a putty knife or trowel. EZ Patch 1 can be applied above water or underwater, and pool plaster will cure underwater.

FIX-A LEAK: We sell a product called Fix-A-Leak, that is an emulsion added to pipes that seeks out and fills small cracks and voids. It does work, on SMALL cracks and voids, but in my opinion, it’s better to find and fix the skimmer leak. Where skimmer leaks are concerned, it’s best to make a solid repair, and not rely on a product that may not work, or may only work for a short time.

Leaks in the Pool Light

Pool light, light cord conduit, and junction box shown, image by ECM Web

The conduit that carries the light cord from the light niche to the light junction box is not sealed, and can become cracked from shifting grounds or freeze damage.

If your pool water level has dropped down below the skimmer, below the returns and has stabilized at the top of the pool light, you probably have a leak in the pool light conduit behind the pool light.

pool-light-leaking - Intheswim

To repair, reach down and remove the screw at 12 o’clock and pull the light out of the light housing, aka light niche. Pull the pool light over the pool coping and onto the pool deck, or let it float in the water during inspection.

Conduit leaks are hard to dye test effectively, so when a pool light is leaking, the common repair is to seal up the opening where the light cord exits the niche and enters into the conduit.

There are 3 ways to seal up a leaking pool light conduit, and you can do it underwater, without draining the pool, but if the water level is already low, it could be easier:

  1. With a golf-ball sized chunk of mixed pool putty, create a mound around the cord as it enters the conduit. Push in and seal tightly against the cord. Allow to cure for 2 days with the light on deck before replacing the light. Can be done underwater with a mask.
  2. With a tube of 100% Silicone, squirt up into the light conduit and around the end of the conduit to seal up the exit for the water. After a good silicone plug is made, allow to dry for 2 days with the light on deck, before replacing the light into the niche.
  3. pool light cord stopperUse a product called a Light Cord Stopper. This is a split rubber plug that fits around the cord; push it into the conduit where it makes a fast seal. This method is preferred for the reason that if you need to replace the lamp down the road, you won’t have to struggle with removing the putty, or silicone, which is especially difficult to remove from the conduit.
Hayward vinyl pool light ring and gasket shown

Vinyl pool lights have a dual gasket seal and an outer faceplate ring, and use two light ring gaskets, to sandwich the liner under the ring and two gaskets. Vinyl pool lights can leak out of the conduit as described above, but may also be leaking from a failed light ring gasket, or simply a loose light ring.

Other vinyl liner pool leaks can occur on the main drain gaskets, or step and swimout gaskets, and wall returns. You will need to lower the water to replace vinyl pool faceplate gaskets, or use the NEMO underwater drill, just for fun!

If you have a vinyl lined pool, small holes can leak a lot of water. They are usually not too hard to find however. To locate a leak in a vinyl liner pool:

  • Turn off pump and dye test around skimmer plate, and all wall fittings, underwater lights and drop in step, seat or spa sections.
  • Inspect closely the corners of the pool, especially where the liner fits tightly. Look for dark spots or leaf debris stuck to the liner.
  • Inspect any ladders to make sure ladder bumpers are in place and the ladder has not cut a hole through the pool liner.
  • Look for areas of the sand which appear to have washed away or eroded.
  • Look for slight staining on the walls, which may indicate rust through.

When you find the leak in a vinyl liner, make a good repair. If you can lower the water to the point of repair you will get a better bond. Use a patch that is rounded, and is several times larger than the hole itself. Clean and dry the area if possible and apply light pressure for 1 minute after patching, then keep fussing with the edges to keep them from curling up.

Use Flexible Sealer to repair vinyl liner leaks. Or you can use a vinyl patch kit. The clear patch material is easy to work with, but these tend to yellow over time, so a matching piece of your own vinyl is better, if you are fortunate enough to have kept the pieces they cut out for the skimmer and the returns, or have a sample piece of your liner pattern.

Leaks in your Pool Plumbing

If your pool has not leaked since you plugged all of the plumbing lines, that could indicate a leak in the underground plumbing. The thought of this can conjure up images of a backhoe operator ripping up the pool deck, but it’s never actually that messy, and many times the problem pipe is easily accessed. Indeed, underground plumbing leaks are rare, but they can occur from deep freeze damage or extremely strong shifting or expansive soils.

pool winterizing plug #7

A process of elimination can also help determine which lines are leaking; Main Drain, Skimmer or Returns. Leave the plug in your main drain and remove the plugs in the skimmers and returns to start up the pump. If it continues to leak, you can unplug the main drain and replug the skimmers to check for skimmer leaks.

Pool return pipe leaks lose more water when the pump is running and pipes are under pressure; whereas a pool suction line leak will pull air into the pump while the pump is under a vacuum, and leak more water when the pump is off.

pool pressure gauge

Pressure testing individual plumbing lines can be performed to determine which line is leaking. Then, the leak can be pinpointed further with more advanced detection tools, which “listen” for the leaking. A leak detection specialist will then literally draw an “X” on the deck or on the dirt, and tell you to “dig here”. A 3’x3′ deck section can be cut out, then the dirt removed to expose the pipe so that a repair can be made, and the deck replaced.

Don’t worry, your worst fears will probably not come true. Many pool plumbing leaks are found directly beneath where the pipe enters the ground, at the 90 fitting, or can be reached by tunneling a few feet under the deck, or found under soft dirt, close to the equipment pad.

Leaks in your Pool Equipment

This one should be pretty obvious to you. In most cases, you will see water running out of your pump, filter, heater or chlorinator. Could be a quick fix or it could require some equipment repair or replacement.

One thing it won’t be is equipment that is slowly drip-drip-dripping. Small drips on the equipment pad are not noticeable in the pool water level, and amount to a very small amount of water loss. Even if you have a fast drip, or several drips – it’s likely less than 50 gallons per day, or under 1/8″ of water level in the average pool.

A leaking filter valve, on DE and sand filters, can go without notice if a backwash hose is constantly connected to the waste port. At some point, the spider gasket in a multiport valve will fail, and after backwashing, water will continue to stream slowly out of the waste port and out of the backwash hose. The same problem can occur if you have a push-pull type of slide valve. Missing plunger o-rings will allow water to constantly flow out of the backwash line.

Plugging the backwash line can stop the flow of water while you order the parts for the repair, but don’t make this a permanent solution. Oh, and installing a slice valve on the waste line? Not a repair I’d be proud of; better to get inside the valve and fix the gasket / o-ring problem.

In most cases, leaking pools are fixed easily. Don’t keep yourself up at night with worst case scenarios, start with the bucket test and proceed through these stages to find your pool leak. If it does turn into an underground plumbing problem, you may need to contact a leak detection expert to help pinpoint the leak – but most pool leaks are not found in the plumbing, but are one of the simpler types mentioned above.

Pool Leak Detection Tools

  1. Pressure Testing Equipment; water, air or gas
  2. Dye Testing Equipment; leak detection dye
  3. Sonic Testing Equipment; hydrophones and geophones
  4. Electronic Testing Equipment; LeakTrac 2200

Reasons to Fix Pool Leaks

Pool leaks not only waste your precious treated and heated pool water, but could lead to other problems such as rusted pool walls, or erosion of a sand pool floor or the supporting soil beneath your pool deck or pool equipment pad.

92 thoughts on “Leaking Pool: Find and Fix Pool Leaks

  1. Kerry Keller

    Good Morning…
    Came about your blog sourcing for help with a pool leak. I have tried just about everything I know…hoping you might have some sage advice!
    I have a gunite pool. At the bottom of the pool I have an area that water is seeping into the pool.I have ground down the marbelite and into the gunite. Cleaned and filled with hydraulic cement. I also am sucking ground level water out of the bottom drain to alleviate pressure forcing water up through the affected area. I have layered the hydraulic cement, drying each application with a heat gun. This after I tried filling entire void with hydraulic cement. I still get seepage coming to surface. I must get this dry as I am painting the pool.
    Of note, I have tried Xypex as well as epoxy sticks. it seems like the water is trickling between the porous gunite and the marbelite.
    Please wave your magic wand and tell me what I can do!
    Please and thank-you.

    • Hi Kerry, I normally get questions about water leaking out of the pool, not into the pool! See another post we have about “Dewatering” during construction. Inground Pool Construction and Groundwater Issues, although the suggestions are for pre-construction, and not sure that any will apply to you very well. You will have to do some major work to get water out of there, maybe too much work. First focus on how to re-route that water, to give it an easier place to go, so that it will ‘daylight’ somewhere else. This can often involve major property changes in grading, or sometimes just one simple fix, like a clogged drain, or rerouting rain water from one area to another, or connecting the downspouts on the house to a pipe that carries the water away. I might also suggest that you switch to Acrylic paint, which can be applied to a wet surface.

  2. Bob Perry

    Hi Davy, I finally bit the bullet and hired a leak detection outfit. It was leaking in the ‘skimmer throats’ – both skimmers but mostly one – cracks in the joints around the tiles. The water level stopped below the entrance of the skimmer but inside the skimmer it is angled down to close to that level. He said water travels up thru the pipe below the skimmer. He puttied them as a temporary fix but said the tiles need taken off inside the skimmer and put back on and sealed with a special cement. He found it w a dye test – had better dye and more experience than me. I never would have found all the leaks. Now I know.

  3. Bob Perry

    Hi Davy. I fixed the light but the pool is still leaking. I removed the light and checked my plug where the wires go into the conduit and everywhere in and around the light housing with pool dye and no leaks. The water drops an inch or so a day and is now below the skimmers. I suspect it will stop where it did before almost 2″ below the skimmers which is about 14″ above the light. I got pool dye and went around to every pipe and nothing. I can’t see any cracks in the walls (pebbletec). I am just stumped as to how the water is getting out of this pool. Before I bring in the expensive guys, can you think of anything else to try?

    • HI Bob, oh that’s too bad, thought we had it licked! That pebbletec, it can seep water thru small voids that may be escaping thru a crack in the wall, not sure if you had it pebbletec’d or it was there when you bought the house, but if you did, was there any horizontal cracks in the wall, at that point? Most common in corners or at top step in shallow end, or spa dividing wall, if you have a spa. 1″ per day is a good size leak, any indicators around the pool? Like spongy soil, green-er grass, visible water? Even downhill from the pool, if there is a hill? I would spend some time looking very closely at the level that it stablilizes at, maybe adding 1/2″ and dye testing that level, all around the pool, or looking for tell tale bits of debris, or if you pool is very clean, toss in a few handfuls of fine straw, and shut off the pump, and see if it gets stuck in a certain area. Then dye test to confirm. I don’t remember if you have plugged returns skimmers and drains, and still been leaking, but that’s a good test, first lower the pH and raise the chlorine level, so the pump can sit off overnight…. there is a few ideas for you, hope one of them helps!

  4. We have a fiberglass pool and it’s leaking 12-20 inches of water a day. So we just plugged everything up. Thanks for you information.
    Hopefully it’s not the pipes. We have a few cracks in the shell but could they cause that much water lose.
    We are having trouble finding anyone in the area to fix the cracks. We live in Langhorne P

  5. Bob Perry

    You are good Davy, real good. I took the light off and the putty sealing the wires to the conduit was just hanging there exposing a 1/2″ hole thru the conduit. I was just about ready to call a leak detection guy before this. You have earned my respect and my business. Thanks so much!

  6. Bob Perry

    Thanks Davy. The top of the light is 14″ below where the waterline stabilized. Are you suggesting that the water stopped leaking because the waterline reached the same level as the leak in the conduit? To confirm, I should be able to put more water in the pool and do a detailed dye test to see water seeping into the light area, correct?

    • Hi Bob, a dye test may not work, the flow is too slow generally, and it’s dark and hard to see, but with some effort you could, but not the light ‘area’, you would need to put dye at the point in the rear of the niche, where the conduit connects. Or just go ahead and seal it with the $5 plug, or with Pool PUtty, or with Silicone.

  7. Bob Perry

    I have a Pebbletec pool about 19 years old. It started leaking so I shut off the pump and have had it off ever since. I did the bucket test to confirm a leak. It leaks about an inch a day but mysteriously stopped about 1.5″ below the skimmers. There is nothing at that water line. I have not seen any water leaking from pump area or backwash. The jets and light are several inches below where the water stopped and my dye test didn’t find anything at these or at the 2 drains. I don’t see any obvious cracks in the pebbletec at that water line. I am totally stumped. Any ideas? Thanks for any feedback.

    • Bob, it could be the light, leaking at a higher level in the conduit, as it rises toward the surface, under the deck. I would get one of the $5 Light Cord Stoppers that we sell, and plug it up.

  8. Andrea Bush

    Question I have a 24ft above ground and recently noticed there are strange gritty pieces almost like sand behind the liner wall and is no longer smooth like it used to be it also feels like ridges I did not see any leaked or tears in the liner I did noticed the top of the liner is not as snug as it was in some areas any thoughts the pool is 5 years old

    • Andrea, could be effloresence or calcium deposits, normally seen on inground pools, but in some cases on above. Or it could be from using a salt system on the pool. When you next replace your liner, scrape down the walls and use wall foam.

  9. hi i have a bestway inflatable ring pool its very old and i would like to use it for the last season it’s currently set up but the problem is the ring keeps deflating and we can’t find the leak i think it’s leaking due to its age since is like 15 years old i have patched all leaks we found but it still deflates is there any substance like mounting foam that i could just pour in the ring to make it last this i’ts last season btw my idea was to fill it with mounting foam and it kinda works but i would need a lot of it and it’s just not worth it(i could buy a new pool for the price) ? thank for you answer in advance and have a nice day

    • Jakob, fill a small squirt bottle with soapy water and spray the ring slowly (try not to get the soap in the pool water), to look for bubbles. Squeezing the ring as you go can help the bubbles appear more visibly. Also look closely at the air fill valve, which leak easily. Patch with silicone, or other liquid vinyl patch, which is better than the vinyl patches. Check your previous patches, they may still be leaking.

  10. I had my skimmer leak patched in early spring, but I believe I may now have another somewhere and one candidate is the pool light conduit and here’s why:

    We had someone working on a backyard project just before the 4th and they accidentally cut into the pool light conduit pipe below the junction box and just below the ground/soil. Water started flowing from pipe and into the hole that was being dug. The pipe was repaired that same day and the next morning we didn’t notice further water so the hole in the ground was filled. My question is should water have even been flowing up and out of the conduit? The place where it was cut was definitely above the light level and probably 4-6 inches above where the water line was at the time. Just this past Friday the water level was below the skimmer and just below the return jets. I didn’t let it drain and further before I filled it back with water. SHould I let the water drain to the light? Any other thoughts. Thanks in advance.

    • Ivan, if you suspect a light leak, there is an easy Fix, the Light Cord Stopper. These act like a plug on the conduit hole, on the back of the light niche. Just remove the light, wrap the Cord Stopper around the light cable and push it into the conduit. They are sold as 3/4″ and 1″, and to fit 12V and 120V cable sizes. If you are unsure about which size conduit is being used, 1″ or 3/4″, but both, they are only $5 each.

  11. STEVE sisney

    My pool is leaking around the gage where the glass thing is

    • Hi, if the pressure gauge is leaking, it is a faulty gauge and needs to be replaced. If you are speaking of the sight glass on the multiport valve, if that is leaking water, then the spider gasket inside the valve may be damaged.

  12. leah rath

    Hi, we have a mystery. Our older gunnite pool lot foot after foot of water during the winter till only a couple feet remained. Dye tested main drain, refilled… Skimmer may have slow leak-regardless, WHERE DID THE WATER GO?

    • Water just went under the pool, into the ground. The underwater light is a common suspect. Or cracks in the pool.

  13. I have a 24’ round pool with a leak. I found on the main center drain there is one screw that will not tighten it just keeps spinning. There is about 30” of water in there currently is there a way I can fix this? Thanks in advance.

    • Kevin, it could be that the brass screw receiver is spinning, having broken loose from the surrounding plastic. What might be easiest is to use a drill (first draining more water of course) and drilling hole on the side of that screw, and then using a thin, stainless steel, self-tapping screw to bite into the plastic frame below (under the liner).

  14. Beverly Painter

    We have a 24-in above ground pool. We opened the pool in April and have had to top off the water every 3 to 5 days. We noticed sanding water around the side of the pool and to the back We found a tear in the liner that we patched and a small hole that we have patched we continue to see loss of water. We turned off the pump and as soon as the water level got below the skimmer it seems as the leaking has stopped. Is there a way to tell if there is a hole in the liner above the water level or could it be something else?

    • Hi Beverly, I saw you on facebook, Davy here. So, I’m thinking it might be your skimmer gasket, and the skimmer faceplate screws may be loose? When tightening skimmer faceplate screws, it is important to use the Large #3 Phillips head screwdriver or drill attachment. It’s the only size that will really grip it for the best tightness, and not strip the screws. Also important is to know that you should crank skimmer faceplate screws down super-tight, until you hear the plastic creak and squeak!

  15. Can I use pool putty to seal around the pool light where the light assembly comes into contact with the plaster or should I seal the inside of the light assembly or both. I have a conduit water leak. Thanks.

    • Hi Luis, pool lights don’t normally leak around the light niche, where it connects or meets the plaster. You could however, do as you say, to fill in darker spots, or if you suspect leaking (it can happen…). For the conduit leak, which is the normal pool light niche, the Cord Stopper product works well. And for extra measure, you can go over top of the Cord Stopper plug with some Silicone sealant or Pool Putty.

  16. dennis stavropoulos

    I have an above ground concrete pool and it is leaking water at the corner of vertical pool wall and flat surface. Any suggestions as to how I find the water leak and who can do repairs on the job.

    • Hi, a temporary repair may be made with epoxy Pool Putty, just mix it up and apply to the crack or void inside the pool. I assume that this is a cinder-block or poured concrete wall pool. The more permanent repair would be to drain the pool, and remove all loose or cracked material, reinforce the region if necessary, then overpack with hydraulic cement, with some steel mesh or thin rebar. then recoat with plaster mix to waterproof it. 90 deg walls are subject to movement in pools. Expansion/contraction with temperature. There may not be much or enough steel used in the corners. Piling dirt up on the outside corner can help normalize temps in the lower part of the wall.

  17. Scott Kraus

    How do you fix the copper pipe connection in the pool light niche? If I remove the dirt fill behind the light niche on the outside of the pool wall below the power cover box for access. Is there a replacement connection part that can be added to do a more permanent fix?

    • Hi Scott, if the light conduit has corroded and detached from the light niche, yes you can remove the copper conduit, and the male-threaded fitting from the niche and replace all with grey PVC conduit. Light niches are usually either 3/4″ or 1″ female threaded, just unscrew the copper fitting and thread in the PVC. In many areas, copper conduit is now not allowed, per electrical code, specifying PVC.

  18. Hi – how do you plug the main drain? Would closing the main drain pipe at the pump work? Thanks.

    • Hi Aaron, for winterization, you don’t plug the main drain, but if you have a positive sealing valve like a Jandy on the main drain pipe, then you would close the valve while blowing air thru it, or once the air has blown the pipe, shut the valve fast, to keep the pipe empty, like a finger on the end of a straw. If you are not blowing the lines, but have the water lowered below the skimmer, closing the valve should keep the water level at that level all winter. Some valves however, will not hold the positive seal, like a finger on the end of a straw, old gate valves and many ball valves for example.

  19. Diver discovered dye intake at one quadrant of the outer drain/outlet gasket. No loss into the drain plumbing. Seems to me further evidence the use of duct tape to hold gaskets in place for a new liner install is a very poor installation.

    • Hi B – it is common however, that a liner installer will use small strips of duct tape to hold on the gaskets for the main drain, so that it will be in place, before the liner is pulled over the pool. Some will use dabs of silicone or other adhesive. I read your other post and since you had leaks also around skimmers and returns and the light, that possibly the installer just didn’t tighten the screws tightly enough, or in the case of the broken return plates, those should have been replaced. Of course there should be two gaskets used on each skimmer, drain, return and light – one below the liner and one on top of the liner. Very tight screws will usually overcome the 1/10th of a millimeter thickness of duct tape, I suspect there was not enough torque applied in your case, they may have been using a cordless drill with a low torque chuck, and/or a #2 bit, when #3 should be used.

      • Once an installer cuts the large holes I would think the gasket can be slipped in with ease. In the skimmer case where I had to replace both gaskets it is easy. Dread if have to do inlets but appears no more water loss. Morning will confirm didn’t just slow it down. For that skimmer I tried tightening the screws before removal (niche ring too) and they were snug although the guy tightening them didn’t use but his arms he looked strong. Larger liner punch outs for the screws would certainly have allowed a tighter(especially with duct tape use) fit rather than bunch up? Perhaps use of sealant where duct tape and small screw hole punctures are utilized? I know some of the screws were more flush with their covers on the old liner than can get to now. So liner is either thinner or bunching up. We selected their thickest wall and floor but dunno

  20. What about if water drops about 1 1/2 feet down and stays just below the slimmer? It a concrete pool with a plastic layer from top about 3ft down.

    • Hi Ginger, so you have fiberglass walls, and concrete floor? We call those Tahitian pools around here… Anyway, those can leak at any of the seams between wall panels, or at 1.5′ down, that could in the step section or underwater light. These pools are also notorious for leaking at the junction of the wall and the floor. You can plug the drain, skimmers and returns to rule out the plumbing and equipment. Good Luck!

  21. ***leak FIxed***
    I have a fiberglass pool that had a leak in the spa conduit. I was able to trace the leak by removing the spa light and tracking with dye. I could tell it was finding it’s way into the conduit. I wanted to try the cord stop before I went with the epoxy because I like the ability to remove the cord stop if ever I had to change the light fixture but, had 2 major concerns. One when they installed the spa light the fixure seemed to big for the niche so in order for them to get the fixure to sit right they had to pull the cord all the way in and left no slack. That meant I could not simply stick the cord stop in the conduit hole then wrap the cord around the fixture and be done. My next issue was the bonding wire that was bonded inside the conduit. I figured it would be tough to manipulate 2 heavy gauge wires then add a cord stop over the wire then push it into the conduit hole behind the fixture that had no clearance. First attempt I was able to easly get the cord stop over the 2 wires and into the hole in order to make sure the cord stop fit right. I had to cut an inch off the fat end of the stop b/c the back of the fixture would not go in all the way with the stop sticking out that much. I then put the modified stop back in then lubed up the cord with dishwashing soap so I could pull the wire through the installed plug from the pool box. Worked great I was able to get the fixture to sit properly, however I could tell the pool still had a minor leak. probably because the wires from the fixture and the bonded wire were bending causing water to find its way through the stopper holes. I finally repeated my steps but added a blob of silicone unto the end of the wire right in the back of the fixture. so when i pulled the wire all the way in the last inch or so would be silicone. I also shot some silicone into the bonded wire hole of the stopper and around perimeter of where the cord stop meets the conduit. let it sit for 24 hours (dry) and I am good. No leaks.
    Sorry for the long post but thought it may help someone else with this problem.

  22. Joseph Lowell

    how do i ground the nitch the ground wire came out when i snaked new pool light wire through. i don’t see any where on inside to attach ground wire.. is grounding nitch necassaty

    • Hi Joseph, some areas have it as an addendum to the NEC, to ground the niche. In my mind it’s a bit of overkill, but perhaps not for 110V lights that are place underwater! What you speak of is not actually a ground wire, but a bond wire, and is attached to the “bonding grid”, surrounding the pool and the metal pool equipment. Imagine a bare #8 copper wire (thick), that makes a 300′ loop, and is connected to or bonded to the ladder, rail and slide leg anchors, pool lights, pool deck rebar, pool shell rebar, pump, filter, heater, in a continuous loop. That’s your bonding grid. In the case of your light, a bonding wire would be attached inside the light niche, onto a proper bonding lug. If not available in the niche, one would be welded in place to the rear of the niche. The other end of the wire, as it goes into the junction box, would attach to the continuous loop bonding wire… You can probably leave it disconnected and never suffer for it – but it is designed for your safety, and if voltage goes astray, the bonding wire is designed to capture and lead it away from the pool.

  23. Pete walker

    Have a 55 year old in ground pool, we found the pool drain line has a leak! I just dug down and found that they took the black hose to wall to metal elbow than black pipe down wall to base of wall where it goes down (now they have it running into the concrete
    Any suggestion?
    Heard theirs a leak repair in line called A&B have you heard of it?

    • Hi Pete, I would recommend that the entire pipe be replaced, all the way into the pool, or you could abandon the current pipe/drain, and install a new dual drain on the low sidewall of the pool, just have to dig all the way down there and bust thru the pool wall (with precision of course!) Then fill in the old drain pot with concrete.

  24. Troy Sonterre

    We have an inground vinal pool that’s leaking at least an inch a day, water level drops an inch above skimmer and stabilizes. We’ve done the dye test no signs of leakage. Changed face plates on all of the water returns, we are out of ideas. Please advise

    • Troy, Well, it has to be somewhere around that level, either from the skimmer gasket, or an underwater light gasket, or perhaps the walk-in step gasket. Something at that level. Maybe a small hole in the liner somewhere, at that level? Pool light conduit could be leaking at that level, just under the deck, a Light Cord Stopper would be a quick way to rule out the light.

  25. I just checked my pool and the water level is very low compared to when I closed it. I usually plug the return jet and keep the water at that level. Now it is at least 2 inches lower than that. I noticed that there is a lot of ice between the skimmer and the return jet. Also my wall under and around the return is rusted. If this is where the water has been leaking is there a way to fix the wall of the pool that has rusted?

    • Hi Janet, great question! On abg pools, the wall return assembly can become looks and gaskets can start to leak water during winter, with the shrink/expand happening between wall and fitting, from temp swings. Also the pressure of an ice sheet on top of the pool, and at that level, can put additional pressure to the fitting. An ice sheet can also open up small weepers in a vinyl liner, due to the greater pressure of the ice on the water. You’ll want to replace the wall return fitting and gaskets, or at least the gaskets, and make a good seal with the new one. If the rust is very light, just use a product like CLR to remove.

  26. Jerseydad

    I had my vinyl pool winterized by a local pool service/supplier in October 2018.
    I lifted the corner of the mesh cover and noticed the water level had dropped to just below the bottom of the frame for the steps. There is nothing else at that level, light is higher as is returns and skimmer.

    I am assuming that there is a leak around the pool steps frame/gasket.

    While the water level is this low I wanted to caulk around the gasket, bottom and up the sides. Is there a recommended caulk for underwater pools? I use a salt chlorine generator if that makes a difference.

    • Hi there, yes, so just a few inches off the shallow end floor? Below everything yes, except the main drain! But let’s hope for the best. I would inspect closely and look for telltale signs of leaking, such as small debris that got sucked into the hole, almost always will be found at the crime scene, er, leak location. Pull back the cover and get in there (now) with boots on, and squat down and look very closely for debris or any sign of a tear in the vinyl. It’s more likely a small hole (or two), and not leaking along the entire frame gasket. Remove the beauty strip however, and do check the tightness on the screws along the bottom. One or two loose screws can cause a leak. For small gaps or tears in the vinyl, I would use something like EZ Patch 28 or Anderson’s Flexible Sealer in that area. If you don’t find a specific hole, but just want to run a bead of sealant along the bottom – just to be sure, either one of those can be used, or you can also use Underwater Magic. After you fix, fill the pool up about a foot, and monitor…

  27. Greg Segallis

    My pool was leaking to just under the top of the light. I was losing about 1-3/4″ per day, which slowed as it approached the top of the light and then stopped. I used a 1″ stopper on the conduit, but the cord was thick enough that the slit in the stopper had a slight gap. So I added pool putty around the cord and stopper. Refilled the pool and had about a 3/8″ leak per day this time – which also stopped at the top of the light.

    I removed the light again, and I could see a slight gap in the pool putty around the cord. I added more pool putty, careful to bring it out a few inches along the cord and also to not bend the cord much putting it back in this time. Still have about 3/8″ leaking per day.

    Should I be looking at the top of niche at the pool wall, a hairline crack in the niche housing, something else, or is it still likely the conduit?

    Thanks for your help!
    -Greg

    • Hi Greg, many a pool has more than one leak. So, it’s still leaking, 3/8″, and still stops at the top of the light. Yes, I would dye test around the rim of the light niche, and also any other cracks or incursions to the pool shell at that water level. If your weather is very warm or windy, you could lose 3/8″ per day to evaporation, surely at least some of the loss could be attributed to that. You can also look in the back of the niche for any bonding lugs or incursion into the niche shell, that could be leaking. It also could be leaking in the main drain pipe, at the same level as the top of the light, or about 18″ below ground, but some of the remaining leak may be evaporation.

      • Greg Segallis

        Thanks! I had two friends in the area measure their evaporation, plus I did the bucket test, and I’m def losing smore than evaporation.

        I was going to try the dye test at the light. I also thought about pulling the light up on deck and putting dye into the niche itself? Is there a good guide on the best way to a dye test?

        Ugh, I hope it’s not the main drain coincidentally at the light level. Not sure how to isolate that. Some way to seal the entire niche for a test would be nice. No other cracks visible. I didn’t really look SUPER closely inside the niche though.

        So maybe dye first. Then drain the water below the light and get back in a take a closer look?

        -G

        • Hi Greg, the light is actually really difficult to dye test, because the conduit is in the upper rear, and it’s dark, and hard to see, even if you can get underwater with a mask, but that’s the idea, is to squirt a small amount of dye near the suspected leak and then wait, sometimes up to a minute, to see if it gets sucked out. . For the main drain, the easiest way to test those is to dive down with a mask and remove the drain cover and plug the drain pipe with a #8 or #9 plug, or a threaded plug SP1022C can also be used, on the side port. Then monitor water level with the drain plugged. If it is the drain, there are ways to pressurize the line softly, while using an emulsion like Fix-A-Leak or Stop Leak. Otherwise further exploration can help pinpoint the location, and it gets dug-up and fixed.

  28. Great post, thank you!

    We have a gunite pool that started leaking immediately after closing last week. Here’s my understanding of our situation: We have two skimmers, three returns, a main drain at the bottom, a hydrostatic relief valve, and no lights. The level had dropped below all skimmers and returns when the folks who closed it returned to look for the leak. The hydrostatic relief valve seemed fine, and they used dye to confirm that water was escaping through the main drain. They didn’t find any cracks around the drain. By plugging the main drain they were able to stop the leak completely. So it seems like there’s a leak somewhere down in the plumbing that returns water from the bottom of the pool up to the above-ground pump. Not good, right?

    Our folks theorize that there was gunk in an existing leak in the plumbing somewhere that got dislodged under the pressure of the closing. Their recommendation is to plug the main drain permanently and just run off the skimmers. I like and trust our guys but something about this doesn’t seem right.

    Three questions: (1) is that a legit explanation? (2) if so, is that something that just happens or could they be responsible for causing it somehow? (3) is their suggested solution a good one?

    Thank you so much in advance!

    • Hi Miguel, what they are saying is that the pressure from the winterization blower, blowing air backwards through the main drain pipe, may have opened up a small crack in the pipe, or separated glued fittings or for some vinyl pools, black poly pipe clamped to grey fittings. It could also be leaking right outside of the main drain, where the pipe connects to the MD. Now it is not normal, to have a main drain begin leaking after blowing it out. If they use a blower box like the Cyclone pool line blower, there is very little chance as it is high volume but low pressure. If they used an air compressor however, as some guys do, they may have accidentally over-pressurized the pipe, but we may never know. For the suggestion of abandoning the main drain and operating off the skimmers only, that is clearly sub-optimal, but many pools exist that way. If you have an automatic cleaner and good circulation, and an effective filter, you may not notice a difference, especially for pools that are not very large or deep, in such cases, the deep end may always look a little hazy, or not as clear, and spring clean-up may take longer. They said that they dye-tested the hydrostatic relief valve? Automatic valves have an o-ring and are spring loaded and sometimes the air volume of blowing out the drain can upset the o-ring, and start a leak – but regular non-automatic hydrostats are threaded in place and that won’t happen. For now you are fine, rest easy. Next spring see how it goes, it may be worth spending $350+ to have the main drain pipe leak pinpointed, to see if it can be fixed, in many cases, the problem is just a few feet below ground, or otherwise fixable. In other cases, the main drain problem lies deep under the pool, and is inaccessible.

  29. I have a leak in my swimming pool. I put water in from my hose for a half hour each day just to keep the water level up. I have had several companies look at my pool and none were able to detect where it is coming from. I used to have an antiquated skimmer with disk filters. One company said it was coming from the skimmer. I had it replaced because of that and because it was so old. And the leak remained. I had another company come over and told me that the new skimmer wasn’t installed properly. There was a main line from the old skimmer to the deep end of the pool that wasn’t caped off and that was where the water was leaking from. I asked him how he knew this and he told me that he heard the leak from his equipment. In order to fix the problem I would have to remove the skipper, cap the line, and install a new skimmer. He told me that the water was coming into the old line and going to the ground. I asked him if the line was from the skimmer to the drain in the deep end, then how was it making its way to the ground. I couldn’t understand his answer. So, DOES THIS ANALYSIS OF MY SWIMMING POOL LEAK SEEM ACCURATE TO YOU?

    • Hi Mike, I think I understand, the theory is that the leak is coming from an abandoned pipe that runs from the main drain to someplace underground near the new skimmer. To test that theory I think you could dive down with a mask and a big breath of air, remove the drain cover and plug the drain line with a threaded 1.5″ plug like SP1022C or with a winter plug, #8 or #9. The main drain is not working now, because it was cut off of the old skimmer and not connected to the new skimmer, nor was it run back to the pump to connect to a valve… right? If so, you don’t need to dig it up and cap it, just plug the drain. If your drain IS working now, it is possible that you will find two open holes in the drain, the current pipe and the old pipe.

  30. Joe Mestre

    E-mailing from South Africa. Have a 40 year old pool. The pool light
    is down a shoot which is accessed externally. The plastic lens is cracked and leaking water into the shoot. How can I repair the light without incurring major repairs

    • Hi Joe, if the crack is small, you may be able to fix it with a sealant like EZ Patch 28, or Underwater Magic. Most pool lights have enough cord behind the lamp to pull the lamp up on deck, but your situation sounds different, something were not familiar with up here…. if patching won’t work, you may need to lower the water level to replace the lens.

  31. In ground pool leaks until around the top of the light fitting. Could I assume this is where the problem is? Thanks in advance

    • Hi Mel, that will usually indicate that the light conduit is cracked, which happens often since they are not winterized and are not too deep beneath the deck. If you add a few inches of water, then plug the pool return lines, and it still leaks, you can safely rule out the return lines, and just go ahead and plug the conduit using the Light Cord Stopper to fit your size conduit hole, there are two sizes, 3/4″ and 1″ diameter. If you look into the niche, hanging upside down with the light removed, you can usually eyeball it. The 1″ connection is about the size of a quarter, the 3/4″ hole is closer to a nickel in size, or you can measure (good luck, lol). There is also a Cord Stopper with 2 holes, if you have a separate bonding wire in addition to the light cord cable. Also there are different cord stoppers for 12V and 120V lights, since the cable diameters are slightly different. Alternate methods of repair include squirting silicone up into the conduit, or packing around where the cord enters with Pool Putty, but Cord Stopper is easier and more permanent.

  32. Dean R. Cowell

    Great info here – I am struggling with a fast leak in our in-ground fiberglass pool. Water drops just below the skim box, and stops – I’ve tried the dye test – didn’t show any sign of leak. I resealed the skim box mouth, but we continue to loose water (up to 2 inches over-night). We do have a light that I’ve tried to seal as well – dye test didn’t really show any escape path through the light. We do have two spek pump jets that did show (at least to my untrained eye) that there was a possible exit through – is it worth plugging these with some winter plugs to check? I’ve also tried sealing (winter plug) the skim – didn’t stop the leak…help 🙂

    • Hi, yes try to plug the Speck jets, and also plug up the light conduit with cord stoppers. Dye tests are usually inconclusive on the light conduit. 2″ in 12 hours is a pretty fast leak, so you should know when you hit the right spot. 🙂 Good luck!

      • Dean R. Cowell

        Thanks – I will give the cord stoppers a try. It’s worth noting, that the water level actually clears the light (it drops down just below the the bottom of the housing) – is it still possible it is the light?

        • Hi Dean, well that changes things somewhat. Usually, the light conduit is in the upper third of the rear of the light niche, and the conduit will rise slowly from that level to run under the deck, a few inches underground, until it turns up and joins the junction box, as shown in the image in this post. If your water stabilizes below the light niche, you must have some other leak going on (could still also be the light niche, but certainly something else besides).

          • Dean R. Cowell

            Thanks! I have a cord stopper arriving today. I’m going to install and see what happens. This blog has helped me more than you know -appreciate your willingness to answer everyone’s questions here.

  33. My pool leaks and it stopped with about 12 inches of water left in the I filled it twice with the same results having trouble finding the leak

    • Hi Mr Duggan, if it leaks to a particular point and then stops leaking, with the pump running, or with the pump off (either way), then you can probably rule out the plumbing. Main drains on some pools may have an automatic hydrostatic relief valve, spring loaded, sealed with an o-ring. These can develop leaks. Vinyl and fiberglass pools can develop leaks around the pool main drain ring gaskets as well. And for a vinyl pool that stabilizes at one level, look closely all around the pool, near the water level, for holes, which sometimes have debris stuck in them, a tell tale sign. Or, add 1-2″ of water and dye test suspected areas to see if the dye gets sucked out of the pool.

  34. Enzo J Santilli

    This is helpful – losing 1/2 inch a day not due to evaporation, and already tried the pool light leak stopper to no avail. Similar to Katherine, I noticed this the last two winters when pool level dropped to below 9-and-3 but not quite to the total bottom of the pool light. I have had a pool service man dye test everything, then called in a leak professional, all to not find anything. I am wondering – can the pool light gasket problem also be true for a fiberglass liner? I did dye test around the outside faceplate, and while the water was not drawn in, it seemed like a little “stuck” near the faceplate. Can this be pool puttied?

    • Enzo, yes fiberglass lights also use two gaskets, one under the wall and one behind the wall, under the light ring. There could be a bit of contraction going on during winter, with cold temps, that causes a leak then, but not during warm weather? It could be puttied, but pool putty is not very flexible, I would use an underwater silicone, clear color, a nice thin bead around the light ring, outside and inside. You could also wait until winter, pull the cover back after a few months, and dye test then.

  35. It seems my leak slows down at the jets. any advice?

    • Hi Cory, the level where the leak stabilizes, slows or stops leaking is a big indication of where to start looking. Filling up above the jets (returns) and shut off pump, you can dye test around the return wall fittings, gasketed on fiberglass/vinyl pools, but sometimes small leaks can be found around concrete pool wall return fittings as well (but not normally). Another test is to leave pump off and plug the wall returns, with rubber plugs or threaded plugs with o-rings (SP1022C), to be sure it’s not the plumbing lines leaking. If your pool is vinyl, you would also check around the pool perimeter at the level of the jets, or whatever level the water stabilizes at – to look for small holes or tears, which sometimes will have bits of debris sucked into the hole, a tell tale sign. Pool light conduits can also leak water, and sometimes the break in the conduit is several inches above the conduit exit point on the light niche, so it does not drain all the way down to the lights, but only down to the level of the break. Cord Stoppers can be used for suspected light conduit leaks.

  36. Hello Davy,

    Great article on leak from pool light in a concrete pool. Built in late 1970’s have been lucky with few costly repairs to this pool–especially over the last 20 years i have owned the home. Am in Central California so few bad winters over the years so I think my leak started from old age or having the acid level too high for a prolonged period (In 2013 the pool was re-surfaced with blown-on fiberglass over then existing plaster). I was NOT told by this highly-regarded fiberglass contractor to greatly reduce the acid added and possibly this higher acidity level corroded the interior of the light box causing the leak which first showed up in late Feb. 2018. After gravity fall of water level over 5 weeks, it settled at the light. On April 2nd, my pool repairman removed the light assembly and reaching over the side of pool, rubbed on A+B Epoxy to stop the leak. Then filled the pool to the normal tile level and added about 30 lbs. of Arm & Hammer baking soda to bring the acid level down ASAP, per his recommendation, to stop the possible corrosion process. This worked until 5/11 when the pool water level began dropping again. As of 6/16, it has dropped about two feet and is presently at mid-level of the light (i.e. 9AM/3PM on a clock). Should I try to A+B Epoxy again or another brand epoxy or just move on to the Cord Stopper. If Cord Stopper do you have a reference website for a step-by-step process on how to DIY? Thanks for a prompt reply!!

    • Hi DG – the pool putty usually works, but it is prone to releaking, if the light cord was slimy, or a good seal was not acheived. Cord stopper is the best solution to light conduit leaking. They are split along the side to slip the stopper over the cord, and then simply pushed up into the hole in the niche, real easy. The hardest part is knowing which one to buy, as there are several, for 3/4″ or 1″ conduit connections, or with two holes, for light cord and bonding wire, if used. So you may need to measure the conduit opening in the rear of the niche. 3/4″ is more common, in my experience, but 1″ is also used a lot in some regions.

      As for the pH corrosion, I think that’s not the issue, if we are talking about water leaking out a broken light conduit pipe. Light niches are stainless steel or heavy ABS, and it would take some seriously acidic water for many years to corrode a hole in the light niche, which is a different issue altogether.

      • Julie Nestor

        Hi, I have an Intex 15×48. I wanted to upgrade my filter. I was looking at saltwater filter as I don’t like to fuss. Your recommendation to buy Intex for my pool. Any help greatly appreciated as this is all new to me. .. I was trying to post my own question but had trouble.thank you for any help

  37. Hello
    We just developed a leak over night. The water seems to have stabilized at the top of the light. I’ve read the earlier post about the cord stopper and will head to the pool store shortly to purchase one but I’m wondering if the conduit would develop a leak so quickly at this time of year?

    • Hi Shawn, not usually, not this time of year. Light conduit usually breaks in the middle of winter, from frost heave lifting the pool deck and ground, or from plain old freeze damage, because of pool water that naturally fills the conduit, and is under the deck close the surface, above the freeze line… but it does not usually happen overnight, in early June – BUT, I suppose it could because what happens in early June? It gets hot, and the pool deck expands with the heat. You may as well plug up the line with a cord stopper, good idea for any pool, but if the leak continues… search on… you will find it and fix it

  38. My pool drains to just below the skimmer. I have eliminated the skimmer, jets and main drain. We just had our concrete pool re-plastered. I gave the crew a new light bulb and gasket etc to install. They did it wrong, the pool light came on for a second then the breaker turned off by itself. The conduit is about 12 inches underground… THe pool shed is on the same deck as the pool and I have noticed water under the pool shed now. The plaster company said they will look at the light in about 2 weeks because the plaster needs to cure underwater. My question is can the light just be fixed and replaced or will the wiring need to be redone as well?… Also, the water stops going down about i inch below the skimmer entrance and does not drain to the light. I am thinking the reason is the water is balanced simply to the conduit height. Is this possible?

    • Hi Lorne, The usual suspect would be the skimmer, but if you have dye tested it, and can see no voids or cracks… then it could be the light, and yes a pool light leak does not need to drain all the way to the light, because the conduit typically rises above the light level, which is where a break can occur, closer to the surface. There is a product called Cord Stopper that is used to seal up pool light conduit leaks. The light tripping the breaker could be that they did not get a tight seal on the light gasket, or used the wrong gasket, especially since you say you see water behind the lens. If the light needs to be replaced, it comes with the cord or wiring to connect to the junction box.

  39. Katherine Deyampert

    My winterized in ground pool had a quick leak after not leaking for the first month being closed down. the water level has stopped at the bottom rim of pool light! I read that if it’s a leak in the light water usually stops at top of niche. I opened and checked for cracks it’s a metal cone so no cracks . My question is with the water level at bottom of light is it most likely in the seal of the light housing ??? Just needs so thoughts on this before begin removing the 10 screws or so and replacing gasket. The water when it did leak out only took about 2weeks to get to this level. Any help or ideas appreciated .ty

    • Hi Katherine, most pool lights leak thru the cord conduit, or the pipe that carries the light cord out of the light niche and to the junction box. The conduit connection hole is usually located in the upper part of the light niche. Since light conduits are not winterized, a very cold winter can cause freeze damage, or sometimes they crack during deck installation or from frost heave of the ground surrounding. These leaks can be fixed by using a Cord Stopper. Now for vinyl liner pools, there is a gasket around the light, between the light niche and the outer ring. These do not normally begin to leak on their own, but can over many years, or if the liner is replaced – the gasket should also be replaced. If the water is leaking through the gasket, often there exists the telltale signs of small debris stuck in and around the void, or hole. You can add an inch of water to the pool and use food coloring, or our leak locating dye, to Dye Test around the light, and watch for the dye leaking out. Niches themselves don’t commonly leak, the steel or copper is usually good for 30-50 years, but a light leak is usually the conduit, or on vinyl pools, the pool light gasket. Now, if you have a vinyl pool, the leak could also be in the vinyl, in another location, but at the same level as the light, could be around the step gasket, if not in the vinyl liner. Hope that helps!

  40. Awesome post! I’ve been looking for some great advice on how to DIY such common leaking and plumbing issues! I look forward reading more post about various plumbing tips and tricks. Thank you!

  41. […] this myself when vacuuming to waste, backwashing or draining the water level during winterization. Pool leaks can rapidly cause a loss of pump prime, as can air leaks in front of the pump (unrelated to water […]

  42. […] the wall surface for any voids at the water level. For more leak detection information see our post: Leaking Pool: Find and Fix Pool […]

  43. […] Leaks in the pool that are found and fixed, can save 1000’s of gallons per year. Fix-A-Leak can seal up small holes in pipes and skimmers, or in vinyl liners. We wrote a blog post last July about how to find and fix pool leaks. […]

  44. […] For more information on pool leak detection, see a related blog post I wrote “Find and Fix Pool Leaks“. […]

  45. Dragonfly440

    In The Swim is the very best company for Pool Supplies…NO ONE has faster shipping or better prices!! I get my order the very next day, here in Ohio. We LOVE In The Swim!!

    But I am VERY disappointed with INTEX Pool Co. Price on pump and filter unit was great but finding parts is very problematic! Even the INTEX website is out of stock for hoses in the middle of the swim season!

    • Stephanie

      Hi. I have leak in my in ground vinyl pool and my pool company can’t seem to locate it. Last summer was my first season in my house and with this pool (not a new pool). After noticing water loss and conducting a bucket test, leak was confirmed. First my pool company sent out a diver to check my vinyl pool. Diver didn’t find anything. At the end of season we realized if we plug all of the pluming lines the leak stops. If we open one and close another (have tried all combinations) pool leaks. Closed pool without finding leak last season. Just opened pool this week. Pool was very full. No leak over winter. Pool company pressure tested lines… suspected leak in suction line under skimmer. They set pool up to run without that line in use. Pool is still leaking. I inch per day now with pump on and off… now pool company doesn’t know what to do an wants to send back a diver. I still think it’s in the plumbing. So frustrated. I don’t know who to call next but I need to figure this out.

      • Hi, did they plug up the skimmer line on both ends, isolating the stretch of pipe completely? Sometimes pools can have more than one leak. 1″ per day is a sizable leak. Dig up the skimmer and make the repair. Probably not in the liner, based on your story. Pool lights can also leak from the light cord conduit, easy to plug with a light cord stopper. Good Luck – you’ll get it! Just keep adding water until you do

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