Water heater leaking? What to do
Turn off the power or gas to the heater first, then find where the water is coming from. The source of the leak will help you work out whether a fitting needs attention or the heater needs replacing. Condensation can look like a leak, especially when the tank is filling with cold water, so wipe it dry and check again after it heats.
Reading the leak
A tank water heater holds 40 to 50 gallons of hot water under pressure. Leaks from the pipes and valves on top or the side are usually fixable. A leak from the bottom of the tank itself, especially with rust, usually means the tank has corroded through, and no repair will stop it.
Water always runs downhill, so a puddle at the base doesn't mean the leak is at the base. A drip from a fitting on top can run down the jacket and pool on the floor. That's why the most useful thing you can do is dry everything off and watch where the water shows up first.
One part deserves special mention: the temperature and pressure , the lever-topped valve on the side or top with a pipe running down toward the floor. It's supposed to open if the tank gets too hot or the pressure climbs too high. A little water from that pipe isn't a malfunction, it's a warning.
Where water heaters leak
Common and usually an easy fix.
The valve at the bottom can weep if it's not fully closed or its washer has worn.
It opens when pressure or temperature gets too high, which is a safety feature doing its job.
Rust eats through the inside over years. This can't be repaired.
| Where you see it | Likely cause | What to do |
|---|---|---|
| Pipe connections on top | A loose or corroded fitting | Snug it a quarter turn. Replace corroded fittings. |
| Relief valve pipe | Tank too hot, pressure too high, or a worn valve | Set 120°F and check your water pressure. Replace the valve if it keeps dripping. |
| Drain valve at the bottom | Not fully closed, or a worn washer | Close it by hand. Cap the outlet with a garden hose cap until it's replaced. |
| Under the tank, often with rust | The tank has corroded through | Shut off the power or gas and the cold supply. The heater needs replacing. |
| Only on cold mornings, then it dries up | Condensation, not a leak | Watch it for a few days. It should stop once the water is fully hot. |
Find the source
- Turn off the power or gasElectric: switch off the water heater's double breaker. Gas: turn the gas control to OFF or PILOT as the label on the heater directs. This keeps the burner or elements from running while you work, and it's the first step if the tank turns out to be the problem.
- Dry it and find the sourceWipe the tank, pipes and valves dry, and lay dry paper towels around the base. Come back in 15 to 30 minutes. Check from the top down: the pipe connections, the relief valve and its pipe, the drain valve, then the base.
- Snug loose fittingsA drip at the pipe connections on top is often a fitting that needs a quarter turn with a wrench. Hold the pipe steady with a second wrench so you don't twist the connection loose. If the fitting is crusty with white or green corrosion, don't crank on it. That one needs replacing.
- Check the relief valveWater from the relief valve pipe means the tank is too hot, the pressure is too high, or the valve is worn. Check that the thermostat is at a normal setting; about 120°F is common. If it keeps dripping at a normal setting, the valve or the house water pressure needs a plumber's attention.
- Tank leaking? Shut the cold supplyIf water comes from the tank itself, close the cold water valve on top (if it's stuck, use the main water shutoff for the house), and plan for a replacement. If it's leaking fast, open a hot tap and drain the tank through a hose to a floor drain or outside.
Watch it done
- Paper towels around the base stay dry after 15 to 30 minutes
- No drips at the pipe fittings on top
- No water coming from the relief valve pipe at a normal setting
Relief valve still dripping? Check your house water pressure with a gauge.
Other drips and false alarms
If the drain valve drips even when closed, screw a garden hose cap onto its outlet as a temporary fix until it's replaced.
Condensation can look like a leak on cold days, especially with a newly filled tank. If the puddle stops once the water is fully hot, it may just be condensation.
If the relief valve keeps opening, borrow or buy a $10 pressure gauge that screws onto an outdoor hose spigot. Anything over about 80 psi is too high. Homes with a pressure-reducing valve often need a small expansion tank near the heater, and a plumber can check both.
What a pro typically charges (a rough estimate; prices vary by area): Valve and fitting repairs usually run $150–$350. A new tank water heater installed typically costs $1,200–$2,500.
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