Why Is My Water Heater Leaking From the Bottom?

What causes a water heater to leak from the bottom?

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

• Drain valve. The drain valve near the bottom of the tank loosens or wears out, and a leaky drain valve generally needs a new valve, according to This Old House.
• Temperature and pressure relief valve. The relief valve releases water when the tank overheats or pressure is too high, and that water runs down the discharge pipe to the floor.
• Condensation. Gas water heaters form condensation when cold water fills the tank, which leaves a small puddle that stops once the water heats up.
• Loose connections. Water from a dripping inlet or outlet pipe on top of the tank runs down the sides and collects at the bottom.
• Corroded tank. Sediment from hard water and a spent anode rod let the steel tank rust through, and a corroded tank cannot be repaired.

Is a water heater leaking from the bottom dangerous?

Yes, a water heater leaking from the bottom is urgent, because the leak can flood the floor, damage wiring and signal a relief valve or tank failure. Angi lists flooding, scalding, gas leaks and electrical hazards as the main dangers of a leaking water heater.

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

What should you do first when a water heater leaks?

The safe first steps for a leaking water heater 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 if the tank, the relief valve or a connection is leaking.

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

Call a plumber for a leaking water heater in the situations below.

• Water is coming from the tank body or rusted seams.
• The relief valve is releasing water or dripping.
• The unit runs on gas and you are not sure how to shut it off.
• You cannot find the source of the leak.
• 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. A new drain valve or relief valve is a small repair, while a leaking tank means replacement, which typically costs $882–$1,810 for a tank-style unit, according to HomeAdvisor. Repair-versus-replace advice and local pricing are on the water heater repair in Lancaster page.

Related water heater problems

A leak often comes with a second symptom. If the tank stopped heating as well, read no hot water in the house: causes and when to call.

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