Short answer: if you smell gas, leave and call 911 or SoCalGas. Otherwise, stay out of standing water near electrical outlets, close the cold-water valve on the pipe feeding the heater (or the home’s main shutoff), turn off power or gas to the heater only if you can reach the control safely, and call a plumber. A leak from the tank body itself usually means the heater has to be replaced, so water heater leak repair in Diamond Bar often ends in a replacement quote.
What to do in the first ten minutes
- Check for gas and electrical danger first. If you smell gas, stop here and leave. If water is spreading toward outlets, the electrical panel or an electric heater’s wiring, do not step into it. Wet floors and live electricity are the most dangerous combination in a leak.
- Close the cold-water supply to the heater. Look for the valve on the cold pipe entering the top of the tank. A lever handle that sits across the pipe is closed; a round wheel handle closes clockwise. Turn it gently. A valve that will not move should not be forced, because a stuck valve can break and make the leak worse.
- If you cannot reach that valve, close the main water shutoff. In many Southern California homes it is near the water meter at the front of the property or where the line enters the house. Closing it stops the flow to the whole home.
- Remove the heat source only if it is safe to do so. For an electric heater, switch off its breaker from a dry spot. For a gas heater, turn the gas control to the off position only if the control is dry and within easy reach. If you are unsure, leave the controls alone and call.
- Relieve pressure at a faucet. With the supply closed, opening a hot-water tap elsewhere in the home lets the system drain down instead of pushing more water out of the leak.
- Contain the water and take photos. Towels, a wet-dry vacuum and a bucket under a slow drip all help. Photograph the heater, the water and anything damaged before you move things, because insurers and landlords usually ask for them.
Find where the water is really coming from
Water runs downhill, so a puddle at the base of the tank does not prove the tank has failed. Dry the area, then check from the top down. A flashlight and a dry paper towel held to each fitting will usually show which joint is wet.
- 1Supply connectors and shutoff valves. Drips where flex lines and valves meet the top of the tank.
- 2Relief valve and discharge pipe. Water from the pipe running down beside the tank.
- 3Tank shell and base. Water pooling underneath, often a failing tank.
- 4Drain valve. Slow drips near the bottom of the tank.
- 5Gas supply and control. Smell gas? Leave first, then call.
| Where you see water | Common cause | Is the heater usually saved? | |
|---|---|---|---|
| Top of the tank, at the pipes | Corroded flex connectors, dripping shutoff valve, or failed dielectric union | Often yes. These are replaceable parts. | Flex line and valve leaks |
| A pipe running down the side of the tank | Temperature and pressure relief valve discharging, from high pressure, thermal expansion or a worn valve | Usually yes, but find out why it opened. | T&P relief valve leaks |
| Low on the tank, near the drain valve | A loose or worn drain valve | Often yes. The valve can be replaced. | This page |
| Water pooling underneath with no wet fitting | Failed tank liner and corroded shell | Usually no. A leaking tank body is not repairable. | Tank corrosion |
| Moisture near a tankless unit | Isolation valves, connections, a condensate line or scale damage | Depends on the cause. | Tankless leaks |
| Wet wall or floor but a dry heater | A supply pipe or another fixture nearby | The heater may not be the problem. | A plumber can trace it |
Gas heater or electric heater: what changes
On a gas water heater, the extra risks are the gas supply and combustion. A heater that is leaking and smells of gas is a gas emergency first and a plumbing job second. A leak that puts out a pilot light is also a reason to leave the relighting to a professional, because a heater that has been wet needs checking before it is lit.
On an electric heater, the risk is wiring and the heating elements sitting in or near water. Cut the breaker from a dry location and avoid opening the access panels. Never reach into a wet electrical compartment.
When to call a plumber right away
- Water is still flowing after you closed the supply valve.
- The leak is from the tank body, or water is pooling faster than you can contain it.
- The relief valve is discharging steadily, or the heater is making loud banging or hissing sounds.
- Water has reached drywall, cabinets, carpet or the garage wall shared with living space.
- You cannot find or close the shutoff valve.
If you want help lining up a local Diamond Bar plumber, the referral process is simple: you describe the leak and your address, and if an independent provider covers your area, you speak with them directly about fees, arrival time and scope.
Need a plumber for this? Describe the leak and your address. If a provider covers your area, you can ask about fees, timing and scope before agreeing to anything.
Call +1 (909) 760-1466After the leak is controlled
Once the water is stopped, dry what you can. Wet drywall, insulation and carpet padding can hold moisture for days, so read our guide to water damage after a heater leak for what professional drying involves and how long you have. If the heater is more than about a decade old, ask the plumber whether repair or replacing the leaking water heater makes more sense.
Local conditions matter too. In Walnut, Pomona and parts of Rowland Heights the water is hard, which speeds up scale and corrosion; see our pages for Walnut and Pomona for details.
Frequently asked questions
Should I turn off the water heater if it is leaking?
Yes, if you can do it safely. Close the cold-water supply first. Then switch off the breaker for an electric heater, or turn the gas control to off for a gas heater, only when the control is dry and easy to reach. If you smell gas, leave instead.
Can I keep using a leaking water heater?
No. An active leak can get worse without warning, can damage the floor and framing, and can point to a failing tank or a safety valve that is opening for a reason. Keep it off until a plumber has inspected it.
Why is my water heater leaking from the bottom?
Water often runs down from a fitting above, so check the top connections and the relief valve pipe first. If every fitting is dry and water still pools under the tank, the tank liner has usually failed, and the heater generally has to be replaced.
Will a plumber come the same day?
That depends on the provider, the time of day and your address. When you call, ask for the expected arrival window, the diagnostic or trip fee and whether the fee applies toward the repair before you agree to a visit.
Does homeowners insurance cover a water heater leak?
Policies differ. Sudden and accidental water discharge is often covered while gradual leaks and the failed heater itself often are not. Photograph everything and ask your insurer before permanent repairs, and keep receipts.
Sources and further reading
Related guides
- Replacing a leaking water heaterWhen a leak means replacement, what a California-compliant installation includes, and how permits and bracing fit in.
- Leaking T&P relief valveWhy the relief valve or its discharge pipe drips, which causes are harmless, and which are warnings.
- Water damage after a heater leakWhat to do about wet floors and walls, what professional extraction and drying involves, and why timing matters.