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Leaking water heater: what to do and what it means
Shut off the cold water supply to the heater and turn off its gas or power. Then find where the water is coming from: leaks at fittings and valves can usually be repaired, but a leak from the tank itself means the heater needs to be replaced.
A puddle by the water heater is worth taking seriously but not panicking over. Plenty of leaks come from parts that can be replaced. The goal is to stop the water, protect the area, and work out exactly where it's coming from.
First, make it safe
- Close the cold water supply valve on top of the heater (or the main if you can't find it).
- Turn the gas control to Off, or switch off the breaker for an electric heater.
- Keep clear of standing water near outlets or electrical equipment.
- If water is still coming out, call (303) 472-4368.
Where leaks come from
- Top of the tank: loose or corroded connections on the hot and cold lines, or a failing nipple or dielectric union. Repairable.
- Temperature and pressure relief valve: a drip or discharge from the valve or its pipe. Replacing the valve is easy; the important part is finding out why it opened. High water pressure, thermal expansion with no working expansion tank, or overheating are common causes.
- Drain valve: the valve near the bottom can weep, especially plastic ones. Repairable.
- Tank seam or bottom: water from under the jacket or a rust-streaked seam means the steel tank has failed. That's a replacement.
- Condensation: on gas heaters, a cold tank can drip condensation onto the burner when it first fires. It stops as the tank warms. If it doesn't, it isn't condensation.
Why tanks fail
Inside the steel tank is a glass lining and a sacrificial anode rod that corrodes instead of the tank. Once the anode is used up and the lining has cracks, the steel rusts through. Sediment, high pressure and age speed that up. That's why flushing and checking the anode are worth doing on a younger tank; see maintenance and flushing.
Protecting the house next time
A drain pan piped to a drain helps where a heater sits above finished space, and is often required there. A working thermal expansion tank keeps pressure in check when the home has a pressure-reducing valve or check valve. When we replace a heater, we look at both.
Signs of a leaking water heater
- A puddle or damp floor around the base
- Water dripping from the relief valve pipe
- Rust streaks on the tank or fittings
- Hissing or sizzling under the burner
- Rusty hot water
- Wet insulation or drywall near the heater
How a visit goes
- Stop the waterWe help you shut off the supply and the gas or power on the phone if needed.
- Find the sourceFitting, valve, condensation or tank. Each has a different fix.
- Repair or replaceValves and fittings get repaired. A failed tank gets replaced, ideally with the expansion tank and drain pan sorted at the same time.
- Check the causePressure, expansion and relief valve discharge, so the next heater doesn't meet the same fate.
What's different here
- Altitude. Gas burns with less oxygen along the Front Range, so burners and venting have to be set up for elevation per the manufacturer.
- Winter demand. Colder incoming water in winter means the heater works harder and recovers more slowly, which exposes weak parts.
- Pressure-reducing valves. Many metro homes have a pressure-reducing valve at the main. It makes the system closed, so a working expansion tank matters for relief valve health.
What affects the cost
Every home is set up differently, so we price the job after we've seen it. These are the things that move the number.
- Source of the leakA drain valve vs. a failed tank are very different jobs.
- Replacement modelSize, gas or electric, and low-NOx compliance for gas.
- Water damageDrywall and flooring repairs are separate from the plumbing.
- AccessAttics, closets and tight rooms take more time.
- Code updatesExpansion tank, pan, discharge piping and gas shutoff.
- PermitReplacement is permitted work in most metro cities.
Questions we hear
Can a leaking water heater tank be repaired?
No. Once the steel tank leaks, it has to be replaced. Leaks from fittings, the relief valve or the drain valve can be repaired.
Is a leaking water heater dangerous?
The main risks are water damage and electrical hazards near standing water. A relief valve that keeps discharging can indicate a pressure or temperature problem that needs attention. Shut it down and call.
Why is my relief valve dripping?
Usually high water pressure, thermal expansion without a working expansion tank, or a worn valve. Replacing the valve without checking pressure often doesn't solve it.
Should I turn off my water heater if it's leaking?
Yes: close the cold supply and turn off the gas or power until it's looked at.
Can I still use hot water?
Not until the leak is understood. If it's a tank leak, using it can make things worse.
Will insurance cover water heater damage?
That depends on your policy. Photos of the damage and the heater label help with any claim.
Related services
Water Heater Repair & Replacement
Tank water heaters that leak, run out of hot water or won't light. Repaired when it makes sense, replaced when it doesn't.
Leak & Pipe Repair
Pinhole leaks, failed fittings, frozen and split pipes, leaking shutoff valves and supply lines.
24-Hour Emergency Plumbing
Burst pipes, active leaks and water heater failures that can't wait.
Leaking water heater: what to do and what it means near you
We're based in Thornton and work across the Denver Metro:
Emergency plumber by city
Water leaking now? Shut off the main, then call.
Something leaking, dripping or cold?
Call and tell us what's going on, or pick a time online. If it's not something we handle, we'll say so.