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Fix a water heater that leaks

We'll locate the leak source—drain valve, T&P valve, or tank—then tighten, replace, or tell you when to call a pro.

Troubleshooting · Home plumbing
15–60 min
What you'll need
  • Adjustable wrench
  • Replacement drain valve or T&P valve (if needed)
  • Hose to drain the tank
  • Pipe tape or thread sealant
Step 1 of 9

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Choose the option that matches what you see. You can jump straight to that section.

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Steps

Goal: Shut off power or gas and water, locate the leak, then fix the valve or call a pro.

  • Shut off power or gas and the cold water supply. Dry the area and watch where water appears.
  • Good: You found the source—drain valve, T&P valve, or fittings. Proceed to the matching section.
  • Bad: Water from the tank seam or bottom—tank leak. See When to get help.

Locate the leak

Goal: Identify the exact leak source before making repairs.

  • Check the drain valve at the bottom, the T&P valve on the side or top, pipe fittings at the top, and the tank body.
  • If the tank itself is leaking, shut off water and gas or power, and call a plumber—tank leaks cannot be repaired.
  • Good: You know the source. Proceed to Fix drain valve or Fix T&P valve.

Fix drain valve

Goal: Tighten or replace the drain valve if it is the leak source.

  • Try tightening the drain valve gently (quarter turn). Do not overtighten.
  • If it still leaks, drain the tank, unscrew the old valve, install a new one with pipe tape on the threads, refill, and restore power or gas.
  • Good: The drip stops.
  • Bad: Still leaks after replacement—call a plumber.

Fix T&P valve

Goal: Test and replace the T&P valve if it leaks.

  • Test by lifting the T&P lever briefly. Water should flow briefly then stop. If it keeps dripping after releasing, replace the valve.
  • Shut off water and power or gas. Drain below the valve. Unscrew the old T&P valve, install a new one with the same rating, reconnect the discharge pipe. Refill and restore.
  • Good: The drip stops.
  • Bad: Still leaks after replacement—call a plumber.

When to get help

If the tank itself is leaking—water from the tank seam, bottom, or sides—the tank has failed. Shut off water and gas or power, and call a plumber. Tank leaks cannot be repaired.

If you smell gas, evacuate immediately. Call 911 or your gas utility from outside.

Verification

  • No water drips from the drain valve, T&P valve, or fittings.
  • The area around the water heater stays dry.
  • Hot water is available at the fixtures.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Shut off and locate Shut off power or gas and water. Locate the leak source.
  2. Drain valve Tighten or replace the drain valve if it is the source.
  3. T&P valve Test and replace the T&P valve if it leaks.
  4. Pipe fittings Tighten or replace fittings at the top.
  5. Call a pro Tank leak—shut off, call a plumber. Gas smell—evacuate, call 911 or gas utility.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Where the leak appears (drain valve, T&P, fittings, tank)
  • Whether the drain valve or T&P valve was tightened or replaced
  • Steps already tried

Where is the leak source?

Shut off power or gas and water. Dry the area and watch where water appears.

Shut off power or gas and water. Dry the area and wait a few minutes. Check the drain valve at the bottom, the T&P valve on the side or top, pipe fittings at the top, and the tank body. Good: you know the source. Bad: water from the tank seam or bottom—tank leak; call a pro.

Drain valve or fittings Tank or unknown

You can change your answer later.

Is the tank itself leaking?

Tank leaks cannot be repaired. The water heater must be replaced.

If water comes from the tank seam, bottom, or sides—not from a valve or fitting—the tank has failed. Shut off water and gas or power. Call a plumber. Tank leaks cannot be repaired.

Yes No

You can change your answer later.

Is the leak from the drain valve?

The drain valve is at the bottom of the tank. It can be tightened or replaced.

Check the drain valve at the bottom. If it drips from around the stem, try tightening gently (quarter turn). Do not overtighten. Good: drip stops. Bad: still leaks—replace the valve.

Yes No

You can change your answer later.

Tighten or replace drain valve

Tighten the drain valve gently. If it still leaks, drain the tank, replace the valve with a new one, refill, and restore power or gas. The leak should stop.

Done

Is the leak from the T&P valve?

The T&P valve has a discharge pipe. It can drip if faulty or if pressure is too high.

Check the T&P valve on the side or top. If it drips from the valve or discharge pipe, test by lifting the lever briefly. If it keeps dripping after releasing, replace the valve. Verify the new valve has the same temperature and pressure rating.

Yes No

You can change your answer later.

Replace T&P valve

Shut off water and power or gas. Drain below the valve. Unscrew the old T&P valve, install a new one with the same rating, reconnect the discharge pipe. Refill and restore. The leak should stop.

Done

Is the leak from pipe fittings?

Fittings at the top can be tightened or the union replaced.

Check the cold inlet, hot outlet, and dielectric union. Tighten gently. If a fitting still leaks, replace the union or gasket. If the leak persists, call a plumber.

Yes No

You can change your answer later.

Tighten or replace fittings

Tighten fittings gently. If the leak persists, replace the union or gasket. If you cannot fix it, call a plumber.

Done

Call a pro

If the tank is leaking: shut off water and gas or power, call a plumber. Tank leaks cannot be repaired. If you smell gas: evacuate, call 911 or your gas utility from outside.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Where do water heaters usually leak?
Common sources: the drain valve at the bottom (loose or bad seal), the T&P (temperature and pressure) relief valve on the side or top, pipe fittings at the top (inlet, outlet, or dielectric unions), and the tank itself. Tank leaks mean the water heater must be replaced.
Can I fix a leaking water heater myself?
Yes, for drain valve and T&P valve leaks. Tighten the drain valve or replace it. Replace the T&P valve if it drips or leaks. If the tank is leaking, you cannot repair it—call a plumber to replace the water heater.
When should I call a plumber for a water heater leak?
If the tank itself is leaking (water from the tank seam or bottom), shut off water and gas or power, and call a plumber—tank leaks cannot be repaired. If you smell gas, evacuate and call 911 or your gas utility from outside.

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