Water Heater Leaking: What to Do First and What It Usually Means

If your water heater is leaking, first stay safe and stop the water: keep clear of hot water and any wiring, turn the heater off, and close the cold water supply valve. Then find where the water comes from. Leaks from a valve or fitting can often be repaired. Water coming from the tank itself usually means it's time to replace it.

What should you do first when a water heater leaks?

Work through these steps in order. Stop at any step that doesn't feel safe.

1. If you smell gas, leave. Take everyone out of the house. Don't use light switches, appliances or a phone inside. From outside, call 911 or your gas utility, and don't go back in until they say it's safe (AGA).
2. Stay clear of water near electricity. If water has reached outlets, cords or an electric heater's wiring, don't touch them while standing in water. The CDC says never to turn power on or off while standing in water, and to have an electrician shut it off if you'd have to walk through water to reach the main switch (CDC).
3. Keep away from the relief valve if it's spraying. The water can scald.
4. Turn the heater off. For an electric heater, switch off its breaker, if you can reach the panel from a dry spot. For a gas heater, set the gas control to "Pilot" or "Off." Fixr's emergency plumbing guide gives the same steps (Fixr).
5. Shut off the water to the heater. There's usually a valve on the cold water pipe at the top of the tank. If you can't find it, or it won't turn, close the main water shut-off for the house. Fixr notes the main valve is usually where the water line enters the house (Fixr).
6. Contain the water. Use towels, buckets or a wet-dry vacuum, and move boxes and belongings off the wet floor.
7. Take photos. Fixr suggests photographing the damage before cleanup, in case you file an insurance claim (Fixr).

Once the water is off and the area is safe, you can take a calmer look at where it's coming from.

Is it a leak or just condensation?

Not every puddle is a leak. Gas water heaters, especially new or high-efficiency ones, can form condensation. Hot exhaust hits the cold tank surfaces and turns to water, which drips onto the burner area or the floor.

A.O. Smith explains that condensation forms when the burner runs and the tank is still filled with cold water, and that it "should stop when the entire tank water is heated above approximately 115 degrees" (A.O. Smith). It's most common:

• right after a new heater is installed,
• after heavy hot water use refills the tank with cold water,
• in cold weather, when the incoming water is colder.

A.O. Smith's test is simple: wipe up the water, set the heater to "Pilot," and check again after 8 hours. If the floor is dry, it was condensation. If water is back, look at the fittings (A.O. Smith).

Rheem puts it this way: small amounts of condensation are normal, but pooling water means a problem (Rheem).

Where is the water heater leaking from?

Where the water comes from is the best clue to what's wrong and what it may cost. Look with a flashlight, without touching wiring or hot pipes.

From the relief valve or its pipe

The temperature and pressure relief valve (often called the T&P valve) sits on the top or upper side of the tank. A pipe runs from it toward the floor. Watts, a valve maker, explains that these valves are designed to open at 150 psi or 210 degrees Fahrenheit, and that in normal use "no water should be discharged from the valve" (Watts).

Water from this pipe is likely one of two things:

• The tank got too hot or the pressure got too high. Watts says discharge "may indicate an unsafe temperature or pressure condition" that needs prompt attention from a pro (Watts). Don't cap or plug the pipe. The valve is a safety device.
• Thermal expansion. Water expands as it heats. If your home has a backflow preventer or check valve on the main line, the extra volume has nowhere to go, and pressure climbs. Watts says small, repeat drips can be a sign of this, and recommends an expansion tank as the fix (Watts).

A worn valve can also drip on its own. A pressure relief valve replacement runs $100 to $250 (Fixr).

From the pipe connections at the top

The hot and cold pipes connect at the top of the tank. Fixr says some leaks come from valves and fittings that need tightening or sealing (Fixr). These are often among the simpler repairs. A drip that runs down the outside of the tank can look like a bottom leak, so look at the top first.

From the drain valve near the bottom

Most tanks have a drain valve near the bottom, used for flushing. Fixr notes that drain valves can wear out and leak, especially after the tank has been drained (Fixr). A drip from the valve's spout or around its stem usually points here.

• Drain valve replacement: $100 to $200 (Fixr).

From under the tank or the bottom of the tank

Water that seems to come from under the tank, with no drip from above, is the most worrying sign. Rheem says leaks from the bottom often signal tank corrosion, which usually means replacement (Rheem). Fixr also lists holes or cracks in the tank among the causes of leaks (Fixr).

A.O. Smith's guidance is direct: if the fittings are tight and the tank still leaks, replace the heater, because leaking heaters can't be repaired (A.O. Smith).

From a tankless unit

Tankless heaters don't have a tank to fail, but they can leak at pipe connections, valves or the heat exchanger. Noritz lists water leaks among the problems that call for a pro (Noritz). Because tankless units mount on a wall near electrical parts, keep clear of the unit and turn it off at the breaker or gas control if you can reach it safely.

What does a water heater leak usually mean?

Putting it together, here's how the location of the leak tends to line up with the likely problem, from the most fixable to the least:

• Water near a new or recently refilled gas heater, which dries up once the tank is hot: likely condensation, not a leak.
• Drips at the top connections: likely a loose or worn fitting.
• Drips at the drain valve: likely a worn drain valve.
• Water from the relief valve pipe: likely high temperature, high pressure, thermal expansion or a worn valve. It needs a pro's attention.
• Water from under the tank, with the fittings dry: likely a corroded tank. Replacement is the usual answer.

Is a leaking water heater dangerous?

It can be, in a few different ways:

• Electricity. Water pooling around an electric heater, an outlet or an extension cord is a shock hazard. Stay out of the water and leave the power to an electrician if you can't reach the panel from a dry spot.
• Scalding. Water from the tank or the relief valve can be hot enough to burn. The CPSC notes that water at 140 degrees can cause third-degree burns in six seconds (CPSC).
• Gas. Water around a gas heater can affect the burner. If you smell gas, leave first and call from outside.
• Water damage and mold. Even a slow drip can soak flooring, drywall and anything stored nearby. The longer it sits, the more it costs to fix.

A heater that's only dripping a little is rarely an emergency on its own, but it's worth dealing with soon.

When should you call a pro about a leaking water heater?

Call a pro if:

• the relief valve is discharging water;
• water is coming from under or around the bottom of the tank;
• you can't tell where the leak is coming from;
• the leak is near wiring, the gas line or the burner;
• you see rust-colored water or rust on the tank;
• the heater is near or past its expected life.

Rheem says most water heaters last about 8 to 12 years (Rheem). If yours is in that range and the tank is leaking, it's worth pricing a replacement alongside any repair.

You can also run through Bellwick's free check to see the likely causes for your situation and what to ask. Check my plumbing.

What will a pro check?

A pro will usually:

• confirm whether the water is a leak or condensation;
• trace the leak to a fitting, valve or the tank;
• check the temperature setting and the house water pressure;
• test the relief valve and look at its discharge pipe;
• check whether your home needs an expansion tank;
• on a gas heater, check the gas connection, burner and venting;
• look at the age and condition of the tank, and tell you whether a repair makes sense.

Ask them to show you where the water is coming from before you agree to a replacement.

How much does it cost to fix a leaking water heater?

As of 2026, here are national ranges from Fixr. Local prices vary.

• Leak repair: $50 to $600 (Fixr).
• Fixing a leaky valve: about $50 (Fixr).
• Pressure relief valve replacement: $100 to $250 (Fixr).
• Drain valve replacement: $100 to $200 (Fixr).
• Shut-off valve replacement: $100 to $200 (Fixr).
• Too much pressure: $75 to $350 (Fixr).
• Rust problems: $200 to $2,000 (Fixr).
• Typical water heater repair overall: $150 to $750 (Fixr).
• Emergency surcharge: $100 to $200 (Fixr).

If the tank itself is leaking, you're likely looking at a replacement:

• Most homeowners pay between $900 and $3,000 for a new water heater installed (Fixr).
• Tank-style heaters run $600 to $2,500 installed (Fixr).
• Tankless heaters run $1,000 to $4,000 installed (Fixr).
• Removing and disposing of the old unit, if charged separately: $75 to $500 (Fixr).
• Permits: $25 to $1,500 (Fixr).

Water that soaks into floors and drywall adds cost too. The EPA says to dry water-damaged areas within 24 to 48 hours to prevent mold (EPA), so don't let a slow leak sit.

Should you repair or replace a leaking water heater?

Repair usually makes sense when:

• the leak is at a fitting, drain valve or relief valve;
• the heater is fairly young;
• the tank itself is dry.

Replacement usually makes sense when:

• water comes from the tank itself;
• the heater is near or past 10 years old and having problems, which Rheem says often makes replacement the better deal (Rheem);
• the repair would cost more than half the price of a new heater, another point Rheem makes;
• you've had several repairs in a short time.

For a closer look at the numbers, see our guide to water heater repair versus replacement costs.

Questions to ask before you approve the work

• Where exactly is the water coming from, and can you show me?
• Is it the tank, or a part that can be replaced?
• If it's the relief valve, what caused it to open? Do I need an expansion tank?
• Is there a service-call fee, and does it go toward the repair?
• Can I get the price in writing before you start?
• If I replace it, what size and type do you recommend, and why?
• Does the price include removing the old heater and any permit?
• Is your work guaranteed, and for how long?
• Are you licensed and insured for this work where I live?

How can you catch a leak early next time?

• Look at the floor around the heater whenever you're nearby.
• Consider a water alarm or leak detector. Fixr lists leak detectors at $25 to $200 (Fixr).
• Flush the tank regularly. Rheem suggests flushing if it's been more than a year, to clear sediment (Rheem).
• Make sure the relief valve pipe ends where you can see it. Watts says the discharge should be visible so leaks get noticed (Watts).
• Know where your shut-off valves are before you need them.

If the leak came with a loss of hot water, see our guide to no hot water. If the water is coming from a pipe rather than the heater, our guide to a burst pipe walks through the next steps.

The bottom line

A leaking water heater isn't always a dead water heater. Start by turning it off, shutting off the water and keeping clear of hot water and wiring. Then find the source. Condensation, loose fittings and worn valves are often fixable. Water from the tank itself usually means replacement. A relief valve that discharges needs a pro's attention soon, because it's a safety device telling you something is wrong.

When you're ready to talk to someone, check my plumbing to see the likely causes and questions to ask.