You can repair a water heater leak only if it comes from a fitting, a valve or a connection. If water is seeping from the tank body, the steel has rusted through, and no patch holds. The fix is a new heater. To tell which you have, dry everything with a towel, wait ten minutes and watch where the first drop forms.
This page is a spoke of our guide to water heater repair. It shows how to trace the leak, how to drain the tank safely, and when to hand the job to a plumber, which in Los Angeles is sooner than many people expect.
How do you repair a leaking water heater?
Shut off the water, power or gas first. Then find the source: the cold and hot pipe connections on top, the relief valve and its discharge pipe, the drain valve at the bottom, or the tank body. A tightened fitting or a new washer fixes the first. A failed valve is replaced. A leaking tank is replaced entirely.
Check each point in turn:
- Top connections. Water running down the outside of the tank from the top often comes from a loose or corroded pipe fitting. Dry it and look for the drip.
- Relief valve and discharge pipe. A drip from the end of the discharge pipe can mean the valve is worn, or that pressure or temperature in the tank is too high. Do not cap or plug it.
- Drain valve. A slow drip at the bottom valve can sometimes be stopped by closing it firmly. A valve that keeps dripping is replaced.
- Tank body or underside. Water from the base, a wet insulation jacket or rust streaks mean the tank is failing from the inside.
If you are unsure, a plumber can tell in a few minutes. Our page on plumber for a water heater leak covers what a visit involves.
How do you drain a water heater?
Turn off power at the breaker for an electric heater, or set a gas heater to pilot or off. Close the cold water supply valve. Attach a hose to the drain valve at the bottom of the tank and run it to a floor drain or outside. Open a hot tap in the house to let air in, then open the drain valve.
Take care with the first minutes. The water inside can scald, so let the heater cool for a while, or run the hose so nobody is near it. Sediment can clog the drain valve, so open it slowly. When the flow stops, close the valve, turn the cold supply back on and leave the hot tap open until water runs without air. Only then restore power or relight the gas.
An electric element left on in an empty tank burns out within minutes. That is the most common mistake in DIY drains.
LADWP recommends flushing a water heater at least once a year. Minerals drop out of heated water and settle as sand-like deposits, and flushing washes some of them out. A tank drained only through a worn plastic valve may also need that valve replaced, which a plumber does in the same visit.
How do I know if I need to drain my hot water heater?
Drain the tank if you hear rumbling or popping, if the hot water turns cloudy or gritty, if the heater is slow to recover, or if it has not been flushed in a year. Draining is also the first step in replacing an element, an anode rod or a drain valve, and in any repair that opens the tank.
A yearly flush is a habit that costs a little time. In Los Angeles hard water is a reason to do it. LADWP reports average hardness of 147 mg/L as calcium carbonate in the San Fernando Valley and western Los Angeles, 168 mg/L around Silver Lake, downtown and South Los Angeles, and 279 mg/L in the east and the Harbor area. The harder the water, the faster a tank collects scale.
If a tank has not been flushed in many years, draining can stir up so much sediment that the drain valve clogs or begins to leak. Talk to a plumber before you open an old valve on a heater you suspect is near the end of its life.
Before you start: what is safe to do yourself?
You can shut off the water, power or gas, mop up, drain a tank and tighten a hand-tight fitting. You should not touch gas piping, vent pipes, the relief valve discharge or anything on a wet electrical connection. In California gas piping work is done by a plumber with a California contractor license, and a water heater replacement needs a permit in Los Angeles.
A short safety list:
- Gas smell: leave the building and call SoCalGas on 1-800-427-2200 from outside. Call 911 if you are in danger. Do not switch anything on or off.
- Water near electricity: do not stand in water to reach a panel. Turn off power only from a dry spot, or call 911 or the utility.
- Hot water: water from a tank can scald. Wait, and keep children and pets away.
- Relief valve: never plug or cap it. It is the safety device.
LADBS says a plumbing permit is generally required to replace a gas water heater in a single-family home, and the exception is a same-size swap by a contractor in the LADBS contractor registration program. If your leaking tank must be replaced, the permit is part of the water heater installation job. See plumbing permit for a water heater.
What does water heater leak repair cost?
A repair for a fitting or valve is small. Published prices for Southern California put most standard tank repairs at about $150 to $650, a service call at $75 to $150, and major repairs on a tank heater at $500 to $1,500. A leaking tank is a replacement, priced from about $775 to $3,275 for a tank unit by Angi's Los Angeles figures.
These are guide figures from published prices and cost guides, checked in November 2026. The written quote is the real price. For the whole range see water heater replacement cost.
When a repair is not worth it: if the tank leaks, if the heater is more than 10 to 15 years old (the range the U.S. Department of Energy gives for storage heaters), or if the repair would cost more than half of a new unit.
Does the brand change how a leak is fixed?
The method is the same for Rheem, Whirlpool, Bosch and other makes: find the source, replace the failed part, or replace the tank. What changes is the part. A relief valve, element or drain valve must match the model. Give the plumber the brand, model and serial number from the label on the side of the tank.
For electric heaters, a leaking element gasket is a common fault, and it is fixed by replacing the element and its seal after draining. See Rheem electric water heater repair. Bosch and similar small electric units often sit under a counter or in a closet, where a small leak can do damage unseen, so check around them regularly.
Solar hot water systems add collectors, pumps and a storage tank. A leak can come from the roof loop, a pump seal or the tank. Because the system has more parts, ask a plumber who handles solar to look at it, and say so on the quote request.
If your leak is urgent, see our page on emergency water heater repair for the first steps.
Common questions
How long does a plumber take to fix a water heater leak?
A leaking fitting or valve is often a one to two hour job once the plumber is on site. A replacement tank usually takes a half day, with the permit and straps. The plumber can tell you the likely time when they quote, after they see the heater and the leak.
What should I ask before I hire someone to fix a water heater leak?
Ask where the water is coming from, whether the tank is still sound and what a replacement would cost. Ask whether a permit is needed and who pulls it. Ask for the repair and the replacement price in writing, so you can compare them before you decide.
Can I stop a leaking water heater with a sealant or patch?
No. Sealants hold fittings for a short while at best, and nothing holds on a tank that is leaking from rust, because the steel around the hole is thin. Shut off the supply, drain the tank and plan the replacement. A temporary fix on a gas heater is also a safety risk.
Is a leaking water heater an emergency?
A leak from the tank body or a pipe that you cannot stop is urgent, because water damage grows by the hour. Shut off the water, then power or gas. A slow drip from a valve can wait for a booked visit. A gas smell is always an emergency: leave and call SoCalGas.