Why Is My Water Heater Leaking?

Part of The Complete Guide to Home Plumbing

Start by finding the actual source

Dry everything off with a towel, then watch closely for a few minutes to see exactly where new water appears. Water heater leaks generally come from one of four places, and each one means something different.

Leaking from the top

This is usually the least serious case. The cold water inlet and hot water outlet connections on top of the tank can loosen over time, or the fittings on your temperature and pressure (T&P) relief valve can develop a slow drip. Often this is fixable by carefully tightening the connection with a wrench — not over-tightening, just snug.

Leaking from the T&P relief valve itself

This valve exists specifically to release pressure if the tank builds up too much heat or pressure — it's a safety feature, not a defect. A slow drip can mean the valve itself has failed and needs replacing, but it can also mean your tank's pressure is genuinely running too high, which is worth having checked rather than just replacing the valve and moving on.

Leaking from the bottom

This is the leak that usually means replacement, not repair. Water heaters corrode from the inside over their lifespan, and once the tank itself has a crack or a failure point, there's no reliable way to patch it. If you see water pooling underneath the unit itself, start looking into replacement rather than repair.

Sediment buildup

Minerals in your water settle at the bottom of the tank over time. This doesn't usually cause leaking directly, but it does cause popping or rumbling noises, reduces efficiency, and accelerates wear on the tank. Flushing the tank roughly once a year (or following your manufacturer's recommended interval) helps prevent this from becoming a bigger problem later.