You can fix a leaking pool light niche without draining.

Yes, and it’s easier than you think. You don’t need to drain the pool unless the gasket is completely shot or the niche is cracked through the housing.

The trick is underwater epoxy putty. Products like AquaMend, JB WaterWeld, or any “underwater” epoxy stick work fine. You knead it, push it into the leak area (around the conduit entrance, behind the light ring, or where the cable enters), and it cures hard as a rock even when submerged.

First, turn off the breaker to the pool light. Safety first. Then put on a mask and snorkel (or just hold your breath) and clean the area with a stainless steel brush or scrubbing pad. Get as much calcium and crud off as possible. Dry the surface with a rag—just rub it down, you’ll never get it bone dry. Apply the epoxy putty, press it deep into the gap, and smooth it with a wet finger. Let it cure 12–24 hours before turning the light back on.

This works for hairline cracks, bad sealant around the light cord, or a loose conduit fitting. If the leak is bad enough that you’re losing an inch of water a day, you probably need a new niche or gasket—but that’s a drain-and-replace job.

Trying the epoxy first costs ten bucks and an afternoon. Draining the pool costs a lot more.