Why is my water heater leaking from the bottom?

Do this first

1. Shut off the water. Close the cold supply valve on the pipe entering the top of the heater.
2. Shut off the heat source. For gas, turn the control to "off" or "pilot." For electric, switch off the breaker. Never leave an electric tank powered if you plan to drain it.
3. Protect the floor. Towels, a wet vac, and move anything stored nearby.
4. Take photos of where the water is and where it seems to start. A plumber can often tell the cause from them.

Do not open the relief valve to "test" it on a tank you suspect is failing, and do not try to drain a tank with hot water in it unless you know the drain path. The water can scald.

Find the source: four places to look

Where the water comes from	What it means	Fixable?
The pipe that runs down the side from the relief valve	The temperature and pressure relief valve opened or is seeping	Yes. See relief valve dripping
The drain valve near the bottom front	Valve not fully closed, worn washer, or cracked plastic valve	Yes, usually a small repair
Beads of water on the tank or fittings, with no steady drip	Condensation, often on a new tank filled with cold water or around heat pump units	Often normal; see condensation vs leak
Fittings on top running down the side	Loose connector, worn nipple or anode port	Yes
Under the tank with none of the above	The tank has rusted through	No: replace the heater

Why the relief valve fools people. The discharge pipe from the relief valve has to run down and end close to the floor: the residential code says it must terminate no more than 6 inches above the floor or receptor^[2]. So when the valve releases, the water shows up at the base, and it looks like the tank is leaking. Dry the floor, then watch the end of that pipe.

Check the drain valve with a towel. Wipe it dry and wrap a paper towel around it. If the towel gets wet within an hour, the valve is the source.

Condensation shows up as droplets. It tends to appear right after a refill with cold water or on humid days, and fades as the tank heats. A steady puddle that keeps returning is not condensation.

When the tank itself is the problem

If water seeps from under the jacket or the base and none of the other sources check out, the inner tank has corroded through. That cannot be repaired. Rheem's guidance is that repairs only make sense on units with no signs of structural damage, and that tanks typically last 8 to 12 years^[5]. Rust-colored water from the hot taps and rust at the base often show up before the leak.

Plan the replacement soon. Small seeps tend to grow, and a full failure can release the tank's contents onto the floor.

Why a drain pan matters

The model residential code requires a pan under a water heater installed where a leak would cause damage, such as an attic, a closet over finished flooring, or an upper floor^[1]. A pan with a drain line routes a slow leak away and buys time. If yours sits in a spot like that without one, ask the plumber to include a pan in the replacement. Local codes vary, so the plumber will know what your city requires.

What it costs

HomeGuide's national figures (August 2025): a drain or leak repair runs $100 to $1,000 depending on the source, and a relief valve replacement $50 to $300^[3]. A standard tank replacement runs $600 to $3,100 installed, per HomeGuide's January 2026 guide^[4]. See our replacement cost guide for what drives the price.

When to call a pro

• The leak comes from the tank body or from under the jacket.
• The relief valve is releasing water, especially hot water or steam.
• Water has reached the burner area, the controls, or the electrical panels.
• You cannot find the source after drying everything and watching for an hour.