Was your water heater under water? What to do after a basement flood.

If floodwater reached the gas controls, burner, or electrical parts of your water heater, don't relight it or switch it back on. A.O. Smith, one of the largest water heater makers, says any water heater that's been through a flood should be replaced, and gas installation manuals say the same whenever the controls or burner were under water. A tank that looks fine from the outside doesn't change that.

This month's storms put water in a lot of basements, and once the pump catches up and the floor dries, the water heater is the appliance everyone wants back first. Nobody likes cold showers during cleanup. It's also the appliance where rushing costs the most, so here's how to think it through.

Stay out until the power question is settled

If there's still standing water in the basement and it's anywhere near outlets, cords, or the electrical panel, don't wade in to check on anything. Call DTE or your electric utility if you need the power cut to the house, and wait until the water's gone or someone qualified has made the space safe. The water heater will still be there.

If you smell gas at any point, leave the house and call your gas company or 911 from outside.

How to tell if the water reached the parts that matter

Floodwater almost always leaves a line. Look at the outside of the tank, the walls, and anything else nearby for a ring of dirt or debris, and note how high it sits compared to the parts below.

• On a gas unit, the parts that matter are low. The gas control valve (the box with the temperature dial) sits near the bottom of the tank, and the burner is below it, behind a small access cover. If the waterline is at or above that control box, treat the controls as submerged.
• On an electric unit, the lower heating element and its thermostat sit behind the lower access panel, near the bottom of the tank. Wiring runs up the side inside the jacket. If water reached that lower panel, assume the electrical parts got wet.

Water on the floor that never climbed above the base is a different situation, and we cover it further down.

Why a flooded gas water heater gets replaced, not repaired

This isn't us selling you a tank. It's what the manufacturers tell installers. A.O. Smith's technical bulletin on flood damage says any water heater subjected to flooding should be replaced, and gas installation manuals say a unit whose gas controls, burner, or ignition parts were under water needs to be replaced rather than repaired.

The reason is what's inside. The gas control valve has small internal passages and safety components that corrode after sitting in dirty water, and the damage doesn't show from the outside. Most gas water heaters built in the last twenty years also have a sealed combustion chamber with a flame arrestor at the bottom, a screen designed to keep flammable vapors in the basement from reaching the burner. Silt and debris from floodwater can clog it, and it can't be reliably cleaned. A unit that lights and runs fine for a week can still be one that fails in a way you won't notice until it matters.

Electric units: an inspection before the breaker goes back on

An electric water heater doesn't have a burner or gas valve, but it does have heating elements, thermostats, and wiring low on the tank, plus foam insulation between the tank and the outer jacket that soaks up water and stays wet. A.O. Smith's flood guidance covers electric units too. Leave the breaker off until someone has opened the access panels and looked. If the water only brushed the bottom of the jacket, the answer can be different, and we'll tell you honestly which way yours goes, but for a unit that sat in dirty floodwater, expect replacement.

If the water never got that high

If the water stayed on the floor and never reached the control box or the lower access panel, the water heater is probably fine to keep using. Dry the area, and over the next few weeks keep an eye on the base of the tank for rust, which can start where a steel pan or tank bottom sat in water. If a gas unit's pilot won't stay lit afterward or the burner flame looks different, shut it off and call.

It's also a good moment to check the age on the label. If the tank is already past the 8 to 12 year range in our water heater lifespan guide, a flood that it survived is still a reasonable nudge to plan the replacement rather than wait for the next problem.

Photos before cleanup

Before anything gets moved or thrown away, take photos of the waterline on the tank and the walls, the label with the model and serial number, and the room as a whole. Whether any of this is covered depends on your policy, and water that came in through a failed sump pump or a sewer backup is often covered only if you have a separate endorsement for it. Your agent can tell you. The photos help either way.

Then fix why the water got in

A water heater is replaceable. What you want to avoid is doing it twice. If this flood started with a sump pump that lost power or couldn't keep up, our guide on what to do when the power goes out and the pump stops and our sump pump page cover the fixes, from a stronger pump to a battery backup. If the replacement question is where you've landed, our replacement cost guide covers what drives the price.

Quick answers

Can I use my water heater after a flood?

Not if the water reached the gas controls, burner, or electrical parts. A.O. Smith says any water heater that's been through a flood should be replaced, and gas installation manuals say the same when the controls or burner were submerged. Leave an electric unit's breaker off until it's inspected. If the water stayed on the floor below those parts, it's usually fine to keep using.

Does a flooded water heater need to be replaced?

In most cases, yes. A.O. Smith's guidance is that any water heater subjected to flooding should be replaced, and gas installation manuals require it when the controls, burner, or ignition parts were submerged. Electric units sit in the same guidance because of wet wiring and soaked insulation.

How do I know if floodwater reached the gas controls?

Look for the dirt line floodwater leaves on the tank and walls. The gas control box sits near the bottom of the tank with the burner below it. If the line is at or above the control box, treat the controls as submerged.

Countryside Plumbing is a licensed master plumber serving Milford, Novi, Farmington Hills, and southeast Michigan since 1979. Water heater repair and replacement is what we're known for, and we leave your house clean. Free quotes at 248-705-7543.