Wondering what's going on in there?
Where a water heater can leak, in plain English
A tank water heater is a big insulated tank that keeps water hot and ready. Cold water goes in, hot water comes out, and a few safety parts keep the pressure in check. Leaks come from those parts or, at the end of its life, from the tank itself.
- Pipes on top. Cold water comes in and hot water goes out through connections on top. Nuts and fittings can loosen or corrode.
- The relief valve. The T&P relief valve on the side opens if the water gets too hot or the pressure too high. Its pipe runs down toward the floor.
- The drain valve. A spigot near the bottom for draining the tank. It can be left open, or wear out.
- The tank. A steel tank lined with glass. When it rusts through, it leaks from the bottom.
- The cold water valve. Closing it stops water going into the tank. It's the first thing to turn off.
So a leak usually comes from one of these:
- The relief valve: the water's too hot, the pressure's too high, or the valve is worn.
- A loose or corroded connection on top.
- A drain valve that's open or worn.
- Condensation or a nearby pipe, which only looks like a leak.
- The tank itself, which means a new heater.
No hot water at all? Our guide to a water heater that's not making hot water walks you through that.
Hot water smells like rotten eggs? See our guide to water that smells like rotten eggs.
Rather not do it yourself? Call a plumber.
That's a fine choice. Maybe you're busy. Maybe you're selling the house and just want it done right. A plumber can fix a leaking valve or put in a new water heater.
Most plumbers charge $45–$200 an hour, and some add a fee to come out.
Find water heater repair near you
Find water heater repair near me →Opens Google Maps. We don't ask for your number.
What to say
Calling a pro? Here's what to say.
A few lines to read when they pick up, and the questions to ask before anyone comes out.
Before you call
Say this
Hi. My water heater is leaking. When's the soonest you can get here? And what's your fee for the visit? Does it go toward the repair?
Always ask
- What's your fee to come out, and does it go toward the repair?
- Do you charge by the job or by the hour?
- Will you tell me the full price before you start any work?
Watch out if
- They push a full replacement on the first visit for a small problem.
- They won't give you a price before starting.
- They add an emergency fee without telling you first.
Feeling pushed to decide on the spot? You can say no and hang up. You owe nothing for a phone call.
Answer up to 3 quick questions. We'll give you the words a pro uses.
Answer the questions →More of a list person?
Common leaks, causes, tests and costs
Find the row that sounds like your water heater. The quick test is something you can check yourself in a few minutes.
| What you notice | What it probably is | Quick test | Do it yourself | With a pro | Verdict |
|---|---|---|---|---|---|
| Rotten-egg or gas smell near the water heater | You may have a gas leak | None. Leave the house | Pro job | $50–$150 | CALLSee the answer: You may have a gas leak |
| Hot water or steam spraying from the side pipe | The water is overheating | None. Stay back | Pro job | $50–$300 | CALLSee the answer: The water is overheating |
| Relief pipe drips after heating; dial set above 120°F | The water is set too hot | Check the dial on the gas knob | Free | Not needed | FIXSee the answer: The water is set too hot |
| Relief pipe drips after heating; temperature normal | Pressure builds up when the water heats | A plumber tests the water pressure | Pro job | $50–$800 | CALLSee the answer: Pressure builds up when the water heats |
| Relief pipe drips all the time | The relief valve is worn out | Watch the end of the pipe | Pro job | $100–$250 | CALLSee the answer: The relief valve is worn out |
| Wet nut on a flexible hose on top | A connection on top is loose | Dry it and watch for the first drop | Free | Not needed | FIXSee the answer: A connection on top is loose |
| Leak from a soldered or crusty fitting on top | A fitting on top is corroded | Look for white, green or rusty crust | Pro job | $100–$1,000 | CALLSee the answer: A fitting on top is corroded |
| Drips from the end of the spigot | The drain valve isn't fully closed | Turn the handle to the right by hand | Free | Not needed | FIXSee the answer: The drain valve isn't fully closed |
| Leaks where the drain valve meets the tank | The drain valve is worn out | Dry it and watch the joint | Pro job | $100–$200 | CALLSee the answer: The drain valve is worn out |
| Drops form on the tank, then stop | It's condensation, not a leak | Wipe it dry and watch after running hot water | Free | Not needed | FIXSee the answer: It's condensation, not a leak |
| Water from a pipe above or a nearby drain line | The water isn't from the water heater | Dry everything and follow the drips | Pro job | $45–$200 | CALLSee the answer: The water isn't from the water heater |
| Water keeps coming back from under the tank | The tank is leaking | Dry it and watch the bottom | Pro job | $600–$1,800 | CALLSee the answer: The tank is leaking |
2026 U.S. averages, rounded. Pro prices include parts and labor. Most plumbers charge $45–$200 an hour, and some add a fee to come out. Nights, weekends and big cities cost more. See all repair prices
Want proof where it's coming from?
The paper towel test
Dry paper towels show you exactly where the water starts.
- Wipe the tank, the pipes on top, the side valve and the spigot dry.
- Tuck a dry paper towel at each spot: around the top connections, under the end of the side pipe, under the spigot, and around the base.
- Check them after an hour, and again after someone runs hot water.
- Only the base towel is wet, and the tank is beaded with drops: probably condensation.
- One towel is wet: that's your leak. Take the questions at the top.
- The base towel is wet and the others are dry: it may be the tank.
Not sure it's safe to keep running?
Shut it down right away if…
- You smell gas or rotten eggs. Leave the house and call the gas company or 911 from outside.
- Hot water or steam is spraying from the side valve.
- Water is pouring from the tank, or reaching an outlet or wiring.
- The tank is bulging, or you hear loud popping or banging with a leak.
Turn off the breaker for an electric heater, or set the gas knob to OFF. Then close the cold water valve on top. Never cap or plug the relief valve pipe.
Got a big repair quote?
Should you repair it or replace it?
Most water heater leak repairs cost $100–$600, according to Fixr and HomeGuide. A new tank water heater runs about $600–$1,800 installed. Ask yourself three things:
- Where is it leaking? Valves and fittings can be fixed. A leaking tank can't.
- How old is it? A.O. Smith says water heaters last about 8–20 years, depending on the type. The date is on the label.
- The half rule. If the repair costs more than half the price of a new heater, get a replacement price too.
Example: a $150 relief valve on a 5-year-old heater is worth doing. Any leak from the tank of a 14-year-old heater means it's time for a new one.
Ran into a word you don't know?
Water heater words, explained
Tap through these before you go looking. The drawings show roughly what each part looks like.
- Water heater
- The big tank, usually in a closet, garage or basement, that heats and stores your hot water.
- Relief valve (T&P valve)
- A safety valve on the side or top. It opens if the water gets too hot or the pressure too high.
- Relief valve pipe
- The pipe from the relief valve down toward the floor. It carries hot water away safely. Never cap it.
- Drain valve
- The spigot near the bottom, used to drain the tank.
- Cold water valve
- The valve on the cold pipe going into the top. Close it to stop water going into the tank.
- Flexible supply hose
- A bendable hose with a nut at each end that connects the pipes to the top of the tank.
- Expansion tank
- A small tank on the cold pipe that gives heated water room to expand, so pressure doesn't build up.
- Gas knob
- The control near the bottom of a gas heater. It has an ON, OFF and PILOT setting and a temperature dial.
- Breaker
- A safety switch in your home's breaker box (the gray metal panel). Electric water heaters have their own.
- Condensation
- Drops that form on a cool tank, like on a cold glass. Not a leak.
- Sediment
- Minerals from the water that settle at the bottom of the tank. Over the years they help rust the tank.
Still have questions?
Questions people ask most
Why is my water heater leaking from the bottom?
A water heater leaking from the bottom often has a drain valve that isn't closed all the way. If the water comes from under the tank itself, the tank has probably rusted through, and the heater needs replacing.
Is a leaking water heater an emergency?
A leaking water heater is an emergency if you smell gas, hot water is spraying from the side valve, or water is pouring from the tank. If you smell gas, leave and call the gas company from outside. Otherwise, turn off the breaker or set the gas knob to OFF, and close the cold water valve on top. A small drip isn't an emergency, but don't ignore it. Never cap or plug the relief valve pipe.
Is a small drip from a water heater normal?
A little water under a gas water heater can be normal condensation, especially after it fills with cold water. A.O. Smith says the condensation goes away once the tank heats up. Drips from the relief valve pipe aren't normal; A.O. Smith says they almost always mean the home's water pressure is too high. Water from the tank itself is never normal.
Why is my water heater's relief valve leaking?
A water heater's relief valve leaks when the water is too hot, the pressure is too high, or the valve is worn. Turn a gas heater down to about 120°F. If it keeps dripping, call a plumber.
Can a water heater leak gas or carbon monoxide?
A water leak doesn't give off gas or carbon monoxide. But a gas water heater can have a gas or carbon monoxide problem of its own. A gas leak usually smells like rotten eggs, so leave the house without touching switches and call the gas company from outside. The CPSC says carbon monoxide comes from gas and oil appliances that don't work right. Keep your carbon monoxide alarms working. Electric water heaters burn no fuel.
Should I turn off my water heater if it's leaking?
Yes, turn off a leaking water heater until you find the leak. Turn off the breaker for an electric heater, or set the gas knob to OFF. Then close the cold water valve on top. A loose nut or an open drain valve may be a quick fix, but a leaking tank won't get better.
Can a leaking water heater be fixed?
A leaking water heater can often be fixed if the leak is at a valve or fitting, but not if the tank itself leaks. A loose nut or an open drain valve is often a quick fix, and a plumber can replace a worn valve or a corroded fitting. A.O. Smith says a rusted tank can't be repaired and has to be replaced. Fixr puts leak repairs at $50–$600, and HomeGuide at $100–$1,000, depending on where the leak is.
How long will a leaking water heater last?
No one can say how long a leaking tank will last, and A.O. Smith warns that the leak can get worse quickly. A tank that bursts can dump 50 gallons of water or more, Bob Vila notes. Plan to replace a leaking tank soon, and keep it turned off until then if you can.
Who do I call for a leaking water heater?
Call a plumber or a water heater company for a leaking water heater. If you smell gas, leave the house first and call the gas company from outside. If the heater is still under warranty, call its maker too, since a tank leak may be covered.
Will insurance cover a leaking water heater?
Home insurance often pays for sudden water damage when a water heater bursts. It won't pay for the heater itself, NerdWallet says, unless you added coverage for broken equipment. Slow leaks, and harm from poor upkeep, aren't covered either, Allstate says. Read your policy or ask your agent before you count on it.
How much does it cost to fix a leaking water heater?
Fixing a leaking water heater often costs nothing, if it's a loose nut, an open drain valve or condensation. A new relief valve runs about $50–$300. A new tank water heater runs about $600–$1,800 installed, HomeGuide says, and HomeAdvisor puts it at $875–$1,800.
How we built this
The questions follow the order a plumber checks a leaking water heater: where the water comes from first, then the relief valve and temperature, the connections on top, the drain valve, and finally the tank. Each answer makes some causes more likely and others less likely.
Prices are 2026 national averages from published repair-cost guides, rounded. Your local prices will differ.
- A.O. Smith, water heater leaking (read October 2026)
- HomeGuide, water heater repair cost (August 2025)
- Fixr, water heater repair cost (August 2025)
- HomeAdvisor, water heater repair cost (June 2026)
- ConsumerAffairs, plumber labor rates in the cost to repair frozen pipes (June 2026)
- Bob Vila, how to fix a leaking water heater (September 2020; 120°F per the U.S. Department of Energy)
- A.O. Smith gas water heater manual: condensation, smell of gas (October 2016)
- A.O. Smith at Lowe's, what to do if it leaks (read October 2026)
- CPSC, carbon monoxide questions and answers (read October 2026)
- Bob Vila, should I replace my water heater before it fails (January 2023)
- NerdWallet, does homeowners insurance cover water damage (June 2026)
- Allstate, does homeowners insurance cover water damage (January 2026)
How we make money: some links go to parts stores that pay us a small commission, and some pro listings pay us when you call them. Verdicts come from the diagnosis, not from who pays more.