Why Is My Water Heater Leaking From the Bottom?

What are the 5 causes of a water heater leaking from the bottom?

The 5 causes of a water heater leaking from the bottom are listed below, from the most common to the least common.

• Drain valve wear lets water drip from the valve near the bottom of the tank, and a leaky drain valve needs a new valve, according to This Old House.
• Relief valve discharge sends water down the discharge pipe to the floor when the tank overheats or the pressure is too high.
• Condensation forms on gas water heaters when cold water fills the tank, and the small puddle stops once the water heats up.
• Connection leaks at the inlet or outlet pipe on top of the tank drip water down the sides to the bottom.
• Tank corrosion from hard-water sediment and a spent anode rod rusts the steel tank through, and a corroded tank has no repair option.

Is a water heater leaking from the bottom dangerous?

Yes, a water heater leaking from the bottom is dangerous, because the leak floods the floor, damages wiring and signals a relief valve or tank failure. Angi lists 4 dangers of a leaking water heater: flooding, scalding, gas leaks and electrical hazards.

A puddle that dries up once the water is hot is condensation in most cases. A puddle that keeps growing is a leak.

What should you do first when a water heater leaks?

The 5 things you should do first when a water heater leaks are listed below.

1. Turn off the power at the breaker for an electric heater, or set the gas control knob to “pilot” for a gas heater.
2. Close the cold water supply valve on the pipe at the top of the tank.
3. Dry the floor and watch where the water reappears to find the source.
4. Move boxes and stored items away from the water.
5. Call a plumber when the tank, the relief valve or a connection is leaking.

When should you call a plumber for a leaking water heater?

You should call a plumber for a leaking water heater in the 5 situations below.

• Water comes from the tank body or rusted seams.
• The relief valve releases water or drips.
• The unit runs on gas and the gas shut-off is unclear.
• The source of the leak stays hidden.
• The water heater is more than 10 years old.

Related plumbing problems and next steps

How much does it cost to fix a water heater leaking from the bottom?

It depends on the source of the leak: the cost to fix a water heater leaking from the bottom ranges from a small valve repair to a full replacement. A new drain valve or relief valve is a small repair, and a leaking tank means replacement, which costs $882–$1,810 for a tank-style unit, according to HomeAdvisor. Repair-versus-replace advice and local water heater prices are on the water heater repair in Lancaster page.

What other water heater problem comes with a leak?

No hot water is the other water heater problem that comes with a leak in some homes. A tank that stops heating while it leaks has a second fault, and the guide on no hot water in the house lists the causes of no hot water.

Written and fact-checked by the Lancaster PA Plumbers editorial team using This Old House, Angi and HomeAdvisor guidance. Last updated October 29, 2026.