How-To

Water Heater Leak: Warning Signs and What to Do First

A water heater rarely fails without warning. The signs are usually there for weeks — pooling water, rust streaks, a popping sound — before a slow leak becomes a flooded utility closet.

The warning signs, in order of urgency

Rust-colored water or rust streaks on the tank

Rust showing up in your hot water, or streaks running down the outside of the tank — either one points to corrosion happening inside. That's the tank itself failing, not a fitting or a valve.

Pooling water at the base

Even a small amount of water collecting under or around the tank is worth checking. Dry the spot, wait an hour, look again. Comes back? Something's actively leaking.

Popping or rumbling sounds

That popping noise is sediment sitting at the bottom of the tank, and it's not a leak by itself — but it wears the tank down faster and often shows up right before one starts.

Age over 10 years

Most tank water heaters last 8 to 12 years. Past the decade mark, tank corrosion becomes the most likely explanation for almost any symptom on this list.

What to do the moment you spot a leak

  1. Shut off the cold water supply valve at the top of the tank — this stops new water from entering.
  2. Turn off power or gas to the unit — an electric breaker or the gas control valve, depending on your type.
  3. Check whether the leak is from the tank body or a fitting. A leaking fitting or valve can sometimes be repaired; a leak from the tank itself means replacement, not repair.
  4. Call a plumber if you're unsure — water heaters involve both plumbing and either gas or high-voltage electrical connections, and misdiagnosing which component failed can be costly.

Prevent the next one from going unnoticed

Nobody checks the water heater closet daily — which is exactly why a slow leak in there can run for weeks before the smell or the stain gives it away. That makes it one of the highest-value spots in the house for a point sensor. See our leak detector guide for options that alert your phone the moment water touches the floor.

FAQ

Common questions

Is it safe to keep using a leaking water heater?

A small amount of condensation can be normal, but any leak from the tank body itself means it's failing and should be shut off, not kept in use.

How long do water heaters last?

Typically 8 to 12 years. Past 10 years, corrosion becomes the most likely explanation for a new leak.

Should I shut it off myself before the plumber arrives?

Yes — shutting off the cold water supply and power or gas is a safe first step that limits damage while you wait.