Water heater leaking: what to do right now

Step one: make it safe

1. Turn off the water. The cold supply valve is on the pipe entering the top of the heater. Turn it clockwise, or a quarter turn if it is a lever. If it will not close, shut the main valve for the house.
2. Turn off the energy. For an electric heater, switch off its breaker. For gas, turn the control to OFF or PILOT. Do not touch electrical parts while standing in water.
3. If you smell gas, leave the house and call the gas utility from outside.
4. Contain the water. Towels, a wet vacuum on a protected outlet, and buckets. Open the nearest floor drain if there is one.

Where is it leaking from?

From the top. Usually a loose or corroded supply connection, or the cold inlet valve. Often repairable.

From the side, at the relief valve. The temperature and pressure relief valve has a pipe running down the side. If it is dripping, the valve may be faulty or the tank pressure may be too high. Have it checked promptly. Do not cap it.

From the bottom, at the drain valve. A drain valve that will not seal can be replaced.

From the bottom of the tank itself. Water appearing from under the jacket usually means the inner tank has corroded through. This cannot be repaired. The heater needs replacing, and the leak can become a flood without warning.

Condensation. A new or recently refilled gas heater can drip condensation briefly. It stops once the tank is warm.

How much water are we talking about?

A tank holds the equivalent of several bathtubs’ worth, and while the supply is on it keeps refilling. A slow weep can go unnoticed for weeks and soak the floor, the base of nearby walls and anything stored beside it. A sudden failure empties the tank and then runs at full supply pressure until someone turns it off.

The damage around it

Water heaters are usually in a basement or a utility closet, close to framed walls, flooring and stored belongings.

• Finished walls nearby wick water up from the base.
• Flooring traps water underneath. Laminate and carpet underpad are the usual losses.
• A closet on an upper floor sends water through the ceiling below.
• The furnace beside it may have taken water into its base.

If water has been on the floor for more than a few hours, check the walls with a moisture meter. A wall that looks fine can be wet behind the baseboard.

Repair or replace

Replace the heater if the tank is leaking, if it is rusting at the base or seams, or if it is past its expected life and showing problems. Fittings and valves on a sound, younger tank are worth repairing.

In Ontario many water heaters are rented. If yours is, call the rental company. Repairs and replacement are normally its responsibility, though the water damage to your home is a matter for your own insurance.

Insurance

A sudden tank failure is the kind of loss many home policies cover for the resulting water damage. The heater itself is usually not covered, and a slow leak that went on for weeks may be treated as gradual damage.

Preventing it

• Put the heater in a drain pan piped to a floor drain
• Fit a leak alarm beside it
• Look at the base for rust or moisture a few times a year
• Replace it on age instead of waiting for it to fail

More: burst pipe and water damage.