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Water Heater Leaking: What to Do Right Now

Last updated October 15, 2026.

Safety first: If you smell gas, leave now and call the gas utility or 911 from outside. If a CO alarm sounds, get everyone outside and call 911. If hot water or steam is spraying from the heater or its relief pipe, stay back. For a serious burn, call 911.

First make sure water isn’t near outlets or the panel. Then find where it’s coming from. A drip from the relief-valve pipe, a fitting, or condensation is often fixable; water from the tank body means the tank needs replacing.

Right now

If water is near outlets, cords, the heater’s controls or the panel, stay out of it and call 911 or your utility. If water is spreading and you already know where your main water shutoff is, close it by hand (no tools, not in standing water; street/meter-pit valves belong to the water utility). Then call a licensed plumber or water heater professional.

Causes, most common first

  1. Relief valve pipe dripping or running. Often high pressure or heat (thermal expansion). Don’t lift, cap or plug it.
  2. Fittings at the top (water lines, valve threads). Slow drips that run down the jacket look like a tank leak.
  3. Condensation on a gas tank after a big cold-water draw: A.O. Smith says it stops once the tank warms, usually 1–2 hours (Use & Care 100277666, p. 23).
  4. Heat pump condensate tube kinked or sitting in water.
  5. Drain valve at the bottom weeping.
  6. Tank body corrosion: the tank itself is leaking.

Checks you can do

Dry the area with a towel and watch where water reappears in the next hour; straighten a kink in a heat pump’s outside drain tube by hand; place a pan or towels. Tankless Rinnai code 79 = leak detected: same steps.

It’s not normal if

The relief pipe hisses or runs continuously; water is steaming; water reaches electrical parts.

Is this normal?

A few drops of water on a new or recently cold gas tank after a big draw is often condensation. A.O. Smith says it usually stops once the tank warms, in about 1–2 hours (Use & Care 100277666, p. 23). Not normal if it keeps coming after that, or if it’s more than a few drops — treat that as a leak and call a licensed plumber or water heater professional.

Know exactly why not

A leaking tank body can’t be patched; the tank must be replaced. Fittings and valves can be fixed, but only after the tank is drained and depressurized. A relief valve that discharges is reacting to too much pressure or heat; finding why (expansion tank, pressure, a failing control) takes gauges.

Start the guided check and choose Water heater, then water at the base.

Sources

Related

Independent information, not an inspection or a confirmed diagnosis. Not attorney-reviewed and not a licensed HVAC review. support@secondwrench.co