Water heater leaking? Make it safe, shut it down, then find the source

If your water heater is leaking, first make sure no one is in danger. If you smell gas, leave the house and call 911 from outside. Otherwise, close the cold-water valve on top of the tank, then turn off the energy source: turn the gas control knob to OFF on a gas heater, or switch off the breaker for an electric one. Then find where the water is coming from. A drip from the temperature and pressure (T&P) relief valve or its discharge pipe usually points to a pressure or temperature problem that a plumber should diagnose. Water seeping from the tank itself usually means the tank has failed and needs to be replaced.

Safety first

• Gas smell (rotten eggs): don’t touch the heater. PG&E’s advice is to alert everyone, leave immediately to an upwind spot, and avoid anything that could spark, including light switches, cell phones, flashlights, matches and vehicles, until you’re a safe distance away. Call 911, then the gas utility. Don’t go back in until the utility says it’s safe.
• Water near electricity: if water has reached outlets, cords, the electrical panel or an electric heater’s wiring, stay out of the water. If you can’t reach the breaker from dry ground, leave and call 911.
• Hot water: tank water can be hot enough to scald. Keep children away and let it cool before handling hoses or valves.
• Sagging ceiling: if the heater sits in an attic or upstairs closet and the ceiling below is bulging, keep everyone out of that room.
• Injury: call 911.

Step 1: Stop the water

The cold-water supply valve is on the pipe that feeds the top of the tank. Turn a round handle clockwise until it stops, or turn a lever handle until it sits at a right angle to the pipe. This stops the tank from refilling. It does not empty the tank.

If that valve won’t turn or keeps leaking, close the home’s main water shutoff instead. It is usually where the water line enters the house, or at the meter near the street.

Step 2: Turn off the energy

• Gas heater: turn the control knob on the gas valve to OFF. If the leak is large or the burner area is wet, also close the gas shutoff valve on the supply pipe (handle at a right angle to the pipe). Don’t try to relight a pilot while the area is wet. PG&E advises following the manufacturer’s instructions and calling a qualified professional if you can’t relight it yourself.
• Electric heater: switch off its breaker at the panel. Don’t turn the power back on until the tank has been refilled. A. O. Smith warns that an element without enough water around it will burn out.

Step 3: Find where the water is coming from

A. O. Smith’s troubleshooting bulletin on puddles around water heaters lists the usual sources:

• The T&P relief valve or its discharge pipe. This safety valve opens if the tank gets too hot or the pressure too high. It is typically rated for 210°F, and for a pressure at or below the tank’s working pressure, generally 150 psi. Occasional weeping often comes from thermal expansion in a “closed” plumbing system. Large, sporadic hot discharges can point to a malfunctioning thermostat. Never cap, plug or remove the valve or its pipe to stop a drip. A. O. Smith’s maintenance guide warns that if the valve doesn’t work, the tank can over-pressurize and explode.
• Pipe connections on top of the tank. Leaking fittings can often be repaired without replacing the heater.
• The drain valve near the bottom. It may not be fully closed, or it may be worn and need replacing.
• Condensation. It can drip after a long draw of hot water and should stop once the tank water is above about 110°F.
• Gas valve connection or electric element gaskets. These can be resealed or replaced.
• The tank itself. A. O. Smith’s guidance is direct: “If the tank is confirmed to have a leak, the tank should be replaced.”

Also check the obvious neighbors, such as a washing machine, a water softener or an air conditioner condensate line. In a garage, the puddle is not always from the heater.

Draining basics

Draining a failing tank limits how much more water ends up on the floor. Do it only if the area is safe and you’re comfortable doing it; otherwise leave it for the plumber. The steps below follow A. O. Smith’s draining instructions:

1. With the cold supply closed and the gas or power off, let the water cool. A. O. Smith suggests turning the heater off for a few hours first. Wear thick gloves and eye protection.
2. Attach a garden hose to the drain valve at the bottom of the tank. Run it to a floor drain, outdoors or into buckets.
3. Open a hot-water faucet in the house so air can enter and the tank drains freely.
4. Open the drain valve. Most tanks take 20 to 40 minutes to drain completely.

Old drain valves can clog with sediment or start leaking once opened. If that happens, close the valve and wait for the plumber.

How long water heaters usually last

• Tank heaters: A. O. Smith puts typical life at 8 to 12 years.
• Tankless heaters: 15 to 20 years with proper care, per the same source.

ENERGY STAR warns that if your water heater is 10 years old or older, “chances are it is heating water inconsistently,” and an old tank can fail altogether and flood your home. Its warning signs are visible corrosion on the lines or the unit, water leaking from joints, seals or seams, rust in the water, and running short of hot water. The heater’s age is usually encoded in the serial number on its label.

In earthquake country, PG&E also advises keeping the water heater securely anchored to the wall so it can’t shift or fall.

Plumber, licensed contractor, or both?

• Call a licensed plumber for anything involving the gas line, venting, the T&P valve, expansion tanks or pressure regulators, and for replacing the heater.
• Call a licensed contractor when water spreads beyond a floor you can mop. That includes water in drywall, baseboards, carpet and pad, cabinets or subfloor, water reaching adjacent rooms or a ceiling below, or materials that stay wet for more than a day or two. Water from a water heater starts clean, but it can degrade the longer it sits, and hidden moisture is how swelling and mold start.
• Often both: when a tank fails and soaks nearby walls, the plumber replaces the heater and the contractor handling the water damage measures, dries and documents the structure.

For your insurer, take photos of the heater, its label and the water before cleanup. Keep the failed parts until your adjuster says you don’t need them.

This guide is general information for homeowners. Your heater’s manual and a licensed plumber are the authority on your specific unit.