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Fix a tank water heater that leaks

We'll pinpoint where it leaks—fittings, T&P valve, drain valve, or tank—then tighten or replace the faulty part, or tell you when to replace the heater.

Troubleshooting · Home appliances
15–45 min
What you'll need
  • Adjustable wrench (for fittings)
  • Channel-lock pliers (for drain valve)
  • Replacement drain valve or T&P valve (if tests show a fault)
Step 1 of 8

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Steps

Goal: Confirm where the leak is, then fix fittings and valves or replace the heater if the tank has ruptured.

  • Inspect the water heater. Check the top (inlet, outlet, T&P valve), bottom (drain valve, tank base), and sides (tank body).
  • Good: You can trace the drip to a fitting, drain valve, or T&P valve—those can be fixed. Proceed to Check fittings and valves.
  • Bad: Water comes from the steel tank body itself—the tank has ruptured. See Tank rupture path.

Check fittings and valves

Goal: Tighten or replace inlet, outlet, drain valve, and T&P valve.

  • Shut off the cold water supply and power or gas. If you smell gas, evacuate and call 911 from outside.
  • Check the fittings at the inlet and outlet. Tighten with a wrench. Replace if corroded or cracked.
  • Check the drain valve at the bottom. Tighten the packing nut or replace the valve if it leaks.
  • Check the T&P valve. Lift the lever briefly—water should flow then stop. If it drips continuously or will not reseat, replace it.
  • Good: No drips when you turn the water back on. Proceed to Verification.
  • Bad: Leak continues and you have ruled out fittings and valves—confirm the tank body is leaking. If so, replace the heater.

Tank rupture path

Goal: Replace the water heater when the tank has ruptured.

  • If water comes from the steel tank body—not from a fitting, drain, or T&P valve—the tank has ruptured. A ruptured tank cannot be repaired.
  • Shut off water and power or gas. Drain the tank. Disconnect the fittings and remove the old heater.
  • Install a new water heater per local code. Call a plumber if you are not comfortable.
  • Good: New heater installed, no leaks.
  • Bad: You need help—call a plumber.

When to get help

If you smell gas, evacuate immediately. Do not turn on lights or appliances. Call 911 or your gas utility from outside. Do not call a technician for an active gas leak—that is an emergency.

Call a plumber if:

  • The tank has ruptured and you need help replacing the heater.
  • Fittings or valves continue to leak after tightening or replacement.
  • You are not comfortable working with water, electricity, or gas.

Verification

  • No water dripping from the heater at any connection.
  • Hot water flows at the taps.
  • T&P valve does not drip when the lever is released.
  • Drain valve is closed with no seepage.

Escalation ladder

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

  1. Confirm leak location Pinpoint where the leak appears—top (fittings, T&P), bottom (drain, tank), or sides (tank).
  2. Fittings and drain valve Tighten or replace inlet, outlet, and drain valve connections.
  3. T&P valve Test and replace the T&P valve if it drips or will not reseat.
  4. Tank rupture If the tank body leaks, replace the heater—it cannot be repaired.
  5. Call a pro Gas smell—evacuate, call 911. Tank rupture or persistent leaks—call a plumber.

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 (top, bottom, sides)
  • Whether the leak is from fittings, valves, or tank body
  • Steps already tried

Where does the leak appear?

Inspect the water heater. Top: fittings or T&P valve. Bottom: drain valve or tank. Sides: tank body.

Inspect the water heater. Trace the drip to its source. Top: inlet/outlet fittings or T&P valve. Bottom: drain valve or tank base. Sides: tank body. If water comes from the steel tank itself, the tank has ruptured.

Top (fittings or T&P) Bottom or sides

You can change your answer later.

Are the fittings or T&P valve leaking?

Tighten fittings. Test T&P valve by lifting lever briefly. Replace if faulty.

Shut off water and power or gas. Check inlet and outlet fittings—tighten with a wrench. Check the T&P valve—lift the lever briefly; water should flow then stop. If it drips continuously or will not reseat, replace it. Fixed: no drips when water is restored. Still leaking: check drain valve or tank.

Yes No (check drain)

You can change your answer later.

Tighten or replace fittings and T&P valve

Tighten loose fittings. Replace corroded fittings or a faulty T&P valve. Turn water back on and check for leaks. If fixed, done. If still leaking, check drain valve or tank.

Done

Is the drain valve leaking?

The drain valve is at the bottom of the tank. Tighten packing nut or replace.

Check the drain valve at the bottom. Tighten the packing nut. If it still leaks, drain the tank and replace the valve. Fixed: no drips. Still leaking from tank body: tank rupture—replace heater.

Yes No (tank body)

You can change your answer later.

Tighten or replace drain valve

Tighten the drain valve packing nut or replace the valve. Drain the tank first if replacing. Restore water and check for leaks.

Done

Is the leak from the tank body itself?

Water from the steel tank body = tank rupture. Cannot be repaired.

Confirm the leak source. If water comes from the steel tank body—not from a fitting, drain, or T&P valve—the tank has ruptured. Tank rupture: replace the water heater. Do not attempt to patch. From fitting or valve: proceed to fix that component.

Yes (rupture) No (from fitting/valve)

You can change your answer later.

Replace the water heater

A tank rupture cannot be repaired. Shut off water and power or gas. Drain the tank. Disconnect fittings and remove the old heater. Install a new heater per local code. Call a plumber if you are not comfortable.

Done

Replace the water heater

The tank has ruptured. Replace the water heater. See tank rupture path. Call a plumber if you need help.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why would a tank water heater leak?
Common causes: loose or corroded inlet/outlet fittings, a leaking drain valve, a faulty T&P valve, or a ruptured tank. Fittings and valves can often be tightened or replaced; a tank rupture requires replacing the heater.
Can I fix a leaking tank water heater myself?
Yes, for loose fittings you can often tighten them. A leaking drain valve or T&P valve can be replaced. If the tank itself is leaking from the steel body, the tank has ruptured—replace the heater. Do not attempt to repair a ruptured tank.
When should I replace a tank water heater that leaks?
Replace immediately if the tank itself is leaking (water from the steel body, not from a fitting or valve). A tank rupture cannot be repaired. If you smell gas, evacuate and call 911 from outside. Call a plumber if fittings or valves leak after tightening or replacement, or if you are not comfortable working with water or gas.

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