Swimming Pool Blog

Inground Pool Light Leak Repair

Preventing the pool from popping
by Rob Cox July 3, 2015

Swimming Pool Light Leaks

Inground swimming pool lights are prone to leakage from the conduit, which is the pipe that carries the light cord from the lamp to the junction box. Pool light conduit is ¾” or 1” gray PVC pipe, running under the deck. Because the point where the pipe connects to the light niche is not sealed, water can enter the pipe. In some cases, water in the conduit may freeze solid, cracking the conduit and start to leak out from the pool. In other cases, the conduit can be cracked during deck placement, or from shifting soils or sliding slabs.


Is the Pool Light Leaking?

The way to determine a pool light leak is by continuing to operate the pool on main drain only (close or plug the skimmers), and allowing the pool water level to drop. If the water level seems to stabilize at the level of the light, or more precisely, just a few inches below the top of the light – you may have a conduit leak. To be certain, you can add a few inches of water and shut off the pump, plugging the skimmers, returns and the main drain pipes, and any other pool plumbing lines, with expansion plugs.

If an inground gunite pool continues to leak with all the lines plugged tightly and the pump shut off – that means that there is a leak in the pool shell or the pool light. Vinyl liner pools have to rule out leaks in the liner, or anywhere the liner was purposely cut; such as the steps, skimmer, return, drain and pool light.

For more advanced pool light leak detection, Anderson Mfg. makes a Pool LIght Tester, allowing you to seal up against the pool wall, and add dye, to watch if it gets sucked out of the conduit.

How Low Can You Go?

If the water level continues to drop below the halfway point of the light, you may have a conduit leak, but there is also some other leak somewhere else. A pool light conduit leak will only leak down to the port on the upper back of the light niche, where the conduit connects.

Pool Light Niche Leaking? hayward light niche

Pool light niches rarely leak, it’s extremely rare for a pool light to be leaking through the shell of the light niche, or around the light niche – 99% of the time a pool light is leaking, water is running out through the light conduit. Vinyl pools however, have the light niche gasket sealed to the pool wall, which has more leak potential, around the niche.

Water inside the Pool Light?

If there is water inside the lens of the pool light, which you can usually see from on-deck, that doesn’t mean that the light is leaking, but it does mean that the lamp gasket has failed, letting water leak inside and surround the bulb. This could be a potentially hazardous situation that should be corrected, but it is not the source of the pool leak.

Fixing a Pool Light Conduit Leak

Relax, we won’t be digging up the broken light conduit, there are a few ways to seal up the light conduit from inside the pool, where it connects to the back of the light niche.

SILICONE:  With the water level  at mid-light or lower, squirt silicone rubber up into the conduit, and around where the light cord enters the port. Clean the areas beforehand, to improve the bond and seal. Makes a fairly permanent repair, but can be a pain if you need to replace the entire light at some point in the future – you’ll have to dig it all out.

POOL PUTTY: Mix up half of the epoxy/resin Pool Putty, and pack it around the (cleaned up) light cord and connection port. Make a cone of putty  that seals up against the niche, cord and port. Fill the pool back up, and allow the light to remain on deck for 24 hours, to allow the putty to dry. Carefully reinstall the light to avoid disturbance to the putty.

Light Cord Stopper LIGHT CORD STOPPER: For the most permanent solution to a pool light conduit leak, seal up the hole in the light niche with a Light Cord Stopper. Made in two sizes, to fit 3/4" or 1" hole, with a hole running through it to allow the light cord to pass through. Just push it in place firmly to keep water from entering the conduit. Good for new pools, too - to prevent a light conduit leak in the first place!


- Rob