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Water under your water heater

Water under a tank heater can come from the drain valve, the relief valve pipe, condensation or the tank itself.

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Mon–Sat · houses, duplexes and units in Alhambra

Updated · 3 min read

If you read one thing

Check the drain valve, the relief valve discharge pipe, the fittings on top, and the burner area. If those are dry and water still pools under the tank, the tank has rusted through and needs replacement.

In this guide
  1. Start at the top
  2. The relief valve pipe
  3. The drain valve
  4. When the tank has failed
  5. Alhambra homeowner questions

Start at the top

Water at the base often comes from above. A leaking connection at the cold inlet or hot outlet runs down the side of the jacket.

Look for crust on the fittings. In Alhambra's very hard water, about 240 ppm per the city report, slow drips leave white or green trails.

Check top fittings then Check relief valve pipe then Check drain valve then Look under burner cover then Tank leak if all dry1Check top fittings2Check relief valve pipe3Check drain valve4Look under burner cover5Tank leak if all dry
The order to trace a water heater leak.

The relief valve pipe

The temperature and pressure relief valve has a pipe running down the side of the tank. Water from its end means the valve opened or is leaking.

The drain valve

Plastic drain valves near the bottom can drip after they are opened for flushing, especially when sediment keeps them from seating.

A cap on the hose threads stops a slight drip. A brass full-port valve replacement fixes it properly.

Fixable leaks: Top fittings; Relief valve or its pipe; Drain valve; Condensation on a new tank. Tank failure: Water from under the jacket; Rust at the base; Leak with all fittings dry; Means replacementFixable leaks• Top fittings• Relief valve or its pipe• Drain valve• Condensation on a new tankTank failure• Water from under the jacket• Rust at the base• Leak with all fittings dry• Means replacement
Leaks that can be repaired versus a failed tank.

When the tank has failed

Once the steel tank rusts through, no part can stop it. Close the cold supply valve at the top, turn the gas control to pilot or off, and arrange a replacement.

Many Alhambra garages have older heaters squeezed into tight alcoves. A replacement is a good time to add proper seismic straps and a drain pan.

Alhambra homeowner questions

Is a new heater supposed to drip?

A little condensation on a cold morning start is normal. Steady water is not.

How do I drain a leaking tank?

Close the cold supply, turn off gas or power, attach a hose to the drain valve and run it outside.

Can a drain pan prevent damage?

A pan with a drain line catches small leaks and directs them away from floors.

Data and references