No hot water, and nothing is leaking

Updated October 2026

First make sure nothing is leaking. Look at the floor around the base of the tank. If it is wet, start with the leak page.

Gas heaters

Many newer gas heaters have a small status light on the gas control at the bottom of the tank. On A. O. Smith's controls, one flash every three seconds means the pilot is lit and the valve is working. No flash means the pilot is out.

Check that the handle on the gas pipe next to the heater is in line with the pipe, which is open. Then follow the lighting instructions printed on the label on the tank itself. They differ by model, and the label is the right set.

If the pilot will not stay lit after two tries, stop there. The manufacturers are blunt that the gas control, the burner and the gas piping are not for the owner to repair.

If you smell gas at any point, leave and call 911 from outside.

Electric heaters

Start at the panel. A tripped breaker is the most common reason an electric heater goes cold. Push it fully off, then on.

If the breaker is fine, the heater has its own safety switch. Turn the breaker off first. Take off the upper access panel on the side of the tank, move the insulation aside, and press the red button on the thermostat until it clicks. Put the panel back and turn the breaker on. Give it an hour.

If the red button trips again, do not keep pressing it. It trips because the water got too hot, and that means a failed thermostat or element.

Hot water that runs out fast

Hot water that runs out sooner than it used to can be a failed part or sediment built up in the tank. Before paying for that repair, check how old the heater is. Manufacturers put the service life of a tank heater at 8 to 12 years, and a repair on a tank near the end of that is money spent twice.

The temperature setting

If the water is merely lukewarm, look at the dial before anything else. The Consumer Product Safety Commission recommends 120 degrees. Massachusetts plumbing code caps residential hot water at 130. A dial that got bumped to "vacation" or "low" explains a lot of cold showers.

When it is the landlord's job

If you rent, you are not expected to relight or reset anything. Hot water is the owner's responsibility under the State Sanitary Code.