Water heater leaks come in two kinds. The first is a leak from something attached to the tank: a pipe connection, a valve, a fitting. Those are repairable. The second is a leak from the tank itself, which means the steel inside has corroded through. That one isn't. Almost everything about the visit follows from which kind you have.
No hot water and a puddle? Start here
- If water is spreading, close the home's main water shutoff if you know where it is.
- Keep people and pets clear of any wet area near electrical equipment.
- Without touching the heater, note whether water appears at the top, the side valve or the base.
- If there's a gas smell as well as water, leave the building and call your gas utility and 911 from outside.
Where water heater leaks start
Top connections. The cold inlet and hot outlet on top of a tank are joined to the house plumbing with connectors or unions. These can loosen, perish or corrode, and water runs down the outside of the tank so it looks like a bottom leak.
The relief valve and its discharge line. The temperature and pressure relief valve sits on the top or side with a pipe running down. Water from that pipe means the valve has opened or is seeping. It may be responding to a real pressure or temperature problem, or the valve itself may be worn.
The drain valve. Near the base, used for flushing. Plastic drain valves in particular can drip, especially after being opened.
Condensation. Mostly on gas tanks when cold water enters and the burner fires. It shows up as drips and sometimes a hiss on the burner.
The tank itself. Once the anode has been used up and the lining breaches, the steel corrodes from inside. Seepage from the base, the seams or under the jacket is the usual sign.
What you'll usually notice
A damp patch on the garage slab that returns after mopping. A rust ring under the tank. A trickle from the discharge pipe that appears after the heater runs. White or green crust on the connections. Hissing when the burner lights. Or, in the worst case, water spreading steadily. Photos of where the water is, taken without touching anything, help a lot.
California factors behind leaks
Hard water speeds up corrosion at connections and consumes anode rods faster, which shortens the time before the tank itself starts to leak. It's why tanks in parts of the inland south and the Central Valley often fail before owners expect. Hardness varies by district; ask your water provider about yours.
Thermal expansion. Many homes have closed plumbing systems where heated water can't expand back into the supply. Pressure rises every heating cycle, stressing connections and making the relief valve weep. An expansion tank is often part of the answer.
Exterior closets expose connections and relief-valve discharge lines to sun and heat, which ages them faster.
Location decides the damage. A garage slab shrugs off a leak; an interior closet, a basement in an older northern home, or an attic does not.
Seismic strapping. A tank that has shifted can strain its connections into leaking. If the heater is replaced, securing the new one is part of the job; the installer confirms what applies at your address.
We'll connect you with a local pro who handles leak calls regularly.
What not to do
Please don't
- Cap, plug or tie off the relief valve or its discharge pipe
- Drain the tank or open the drain valve while the heater is under pressure
- Open electrical covers or touch the gas control on a wet heater
- Try to seal a tank-body leak with tape, putty or sealant
How the technician deals with it
First the heater is made safe: fuel or power off, water supply isolated. Then the technician traces the water to its source, drying surfaces if needed to see where fresh water appears. Connection leaks are resealed or the connectors replaced. A weeping relief valve prompts a check of water pressure and temperature, and the question of thermal expansion, before the valve is replaced. A dripping drain valve is replaced. A tank-body leak means replacement, priced with any strapping, venting and access work included.
What affects the cost
| Source of the leak | Likely outcome |
|---|---|
| Top connection or fitting | Repair: reseal or replace the connector; often among the least costly visits. |
| Relief valve | Repair: valve replacement, plus any pressure or expansion fix the cause calls for. |
| Drain valve | Repair: valve replacement. |
| Tank body | Replacement: priced with strapping, connections, venting and haul-away. |
How long it takes
Finding the source rarely takes long. Connection, drain valve and relief valve repairs are often completed in the same visit. A tank replacement depends on the unit, the location and access, and the installer will give you a realistic plan before starting.
Describe where the water is and we'll take it from there.
Leaking water heater questions
Water at the bottom can come from the drain valve, from the relief-valve discharge pipe, from a leak higher up running down the outside, or from condensation. But water coming from the tank itself at the base usually means the inner tank has corroded through, and that can't be repaired. The technician's first job is telling these apart.
That pipe is the discharge line from the temperature and pressure relief valve. Water there means the valve has opened, because temperature or pressure in the tank rose too high, or the valve has worn and is seeping. Either way it needs a technician. Never cap, plug or block that pipe; it is the tank's safety outlet.
Not necessarily. A newly filled gas tank full of cold water can form condensation on its cold surfaces when the burner fires, and that water can drip down and even hiss on the burner. It typically stops once the tank is up to temperature. If dripping continues after the tank is fully hot, it's worth having the installer check.
Yes, if the leak is from a connection, fitting, drain valve or relief valve. Those parts can be tightened, resealed or replaced. If the water is coming through the tank wall or seams, the lining has failed and replacement is the only real fix. A technician can tell the difference in a few minutes.
Turning off the water supply to the house, using the main shutoff if you know where it is, is the safe step you can take. Leave the heater's gas control, electrical supply and valves to the technician, who will isolate the heater properly on arrival. If you smell gas, leave the building and call your gas utility and 911 from outside.
In hard-water areas, mineral deposits build up around fittings, and where copper meets steel, galvanic corrosion can eat into the joint. Heat and sun in exterior closets speed that up. The technician may replace the connectors with a more suitable type and look at whether an expansion tank or other change would reduce stress on them.
A small, steady drip from a fitting isn't usually an emergency, but it rarely gets better on its own, and a drip from the tank body usually gets worse. A heater inside the living space, or any water near electrical equipment, makes it more urgent. If in doubt, call and describe what you're seeing.
A drain pan catches small leaks and drips and, where it's piped to a drain, can carry them away. It won't hold back a failed tank. Pans matter most where a leak would reach finished floors, such as interior closets and attics. The installer can advise whether one suits your location.