Short Answer
A water heater leaking from the tank itself, usually at the bottom, has corroded through and needs replacing. Leaks at the drain valve, the pipe connections on top, or the relief valve are usually repairable. Shut off the power or gas and the cold water supply first, then find where the water is coming from.
Repipe Solutions is a licensed Houston plumbing company that repairs and replaces leaking water heaters. The first question is always whether the whole unit is finished. Not always. Where the water is coming from tells you almost everything. A drip at a valve or fitting is often a small repair. Water seeping from the tank body is not.
Is a Leaking Water Heater Dangerous?
It can be, and A.O. Smith says a leaking water heater should be treated as urgent and should not stay in use until it has been checked. The risks are:
- Water damage and mold. Even a slow leak soaks floors, walls, and ceilings. The EPA says wet materials dried within 24 to 48 hours will usually not grow mold.
- Scald burns. The water leaking out can be as hot as the tank. The CPSC says most adults suffer third-degree burns from 150 degree water in two seconds, and burns also occur after six seconds at 140 degrees.
- Gas and electric hazards. Water dripping onto a gas burner or reaching wiring is a reason to shut the unit down, not wait. A steady sizzle from a gas heater is covered in our guide to water heater noises.
What to Do Right Now When a Hot Water Heater Is Leaking
- Keep clear of hot water. Do not reach into a puddle under the tank or put your hand near the relief valve outlet until you know how hot the water is.
- Turn off the heat. On an electric unit, switch off its breaker at the panel. On a gas unit, turn the gas shutoff valve near the heater to off, if you are comfortable doing so.
- Shut off the water to the heater. Close the valve on the cold water line that feeds the top of the tank. If that valve will not turn or there is none, close the main shutoff to the house.
- Open a hot faucet. This relieves pressure in the tank and slows a leak. Leave the heater off; an electric tank should never be powered while it may be empty.
- Dry things out. Mop up, run fans, and move anything stored near the heater.
- Find the source using the sections below, then decide whether it is a repair or a replacement.
Why Is My Water Heater Leaking? Find the Source First
Wipe everything dry, then watch where water shows up first. Water often runs down the outside of the tank and collects at the base, so a puddle on the floor does not always mean the bottom is the problem.
| Where You See Water | Most Likely Cause | Usually |
|---|---|---|
| Pipe connections on top | Loose or corroded fittings | Repair |
| Relief valve or its discharge pipe | High pressure, high temperature, or a worn valve | Repair, and fix the cause |
| Drain valve near the bottom | Valve not fully closed or a worn valve | Repair |
| Water under a gas heater only while it runs | Condensation | Often normal |
| Tank body, bottom seam, or under the jacket | Corroded or cracked tank | Replace |
Sources: A.O. Smith and Rheem, which both say a leak from the tank itself usually means replacement, while valve and fitting leaks may be repairable.
Water Heater Leaking From the Bottom
When a water heater is leaking at the bottom, there are four things it can be, and only one of them is the tank.
- The drain valve. Code requires a drain valve at the bottom of every tank heater (Texas IRC P2801.2). A water heater drain valve leaking from its spout usually was not closed fully or has a worn seat. A.O. Smith says a valve that will not close properly is best replaced. Plastic drain valves can catch sediment on the seat during a flush and drip afterward.
- Condensation. A.O. Smith’s technical bulletin on condensation says a typical gas water heater produces about half a gallon of water vapor per hour of operation, and that this is often mistaken for a leak. To test, wipe up the water, turn the gas control to the pilot setting, and check again after 8 hours. If the floor stays dry, it was condensation.
- Water from above. A leak at a top fitting can run down the side and pool at the base. And the relief valve’s discharge pipe is allowed by code to empty into the pan under the heater, so water in the pan may be the relief valve, not the tank.
- The tank itself. If the fittings and valves are dry and water keeps seeping from under the jacket or the bottom seam, the steel tank has corroded or cracked. A.O. Smith’s bulletin is blunt: leaking heaters cannot be repaired. The tank has to be replaced.
Tank leaks usually start from the inside. Sediment from hard water settles on the tank floor and A.O. Smith notes it can cause overheating, cracks, and leaks. A spent anode rod lets the tank start corroding. Our guides to the anode rod and to popping and rumbling sounds explain both in detail.
Water Heater Leaking From the Top
A water heater leaking from the top is usually the better news. A.O. Smith says loose pipe connections develop over time from thermal expansion and normal wear, and that gently tightening a fitting can stop the leak. Do not overtighten, because that can damage the fitting and make it worse.
- Cold inlet and hot outlet connections. Look for drips, green or white crust, or rust where the pipes meet the tank. Crusted fittings usually need to be replaced, not just tightened.
- Heating element gaskets (electric units). These are on the side of the tank behind the access panels. A.O. Smith notes a worn element gasket can leak. Cut power at the breaker before removing any panel.
Water Heater Pressure Relief Valve Leaking
The temperature and pressure (T&P) relief valve is a safety device. Under the Texas residential code it must open at no more than 150 psi or 210 degrees (sections P2804.3 and P2804.4). If it is dripping or discharging, it is either worn out or doing its job.
| Cause | What Fixes It |
|---|---|
| Thermal expansion: heated water has nowhere to go because a check valve or backflow device closes the system | A properly sized and charged expansion tank. Code requires pressure control in this situation (P2903.4.2). |
| House water pressure above 80 psi | A pressure reducing valve. Code caps static pressure at 80 psi (P2903.3.2). |
| Thermostat set too high | Turn it down. A.O. Smith says this can stop the leak. |
| Worn valve, or debris on the seat after testing | Replace the valve. A.O. Smith says a valve that sticks or leaks after testing should be replaced. |
If a new valve starts dripping again, the cause is pressure or expansion, not the valve.
One rule matters more than the rest: never cap, plug, or put a valve on the relief discharge pipe. Code says the pipe must have no valves or tee fittings, no threads at the end, and must end no more than 6 inches above the floor or pan (P2804.6.1). Capping it to stop a drip removes the tank’s protection against overpressure. We replace faulty relief valves as part of our water heater repair in Houston.
Can a Leaking Water Heater Be Fixed?
| Situation | Our Usual Advice |
|---|---|
| Fitting, drain valve, or relief valve leak on a younger tank | Repair |
| Any leak from the tank body | Replace, regardless of age |
| 10+ years old, rusting, or failing in more than one way | Replace |
| Repair would cost more than half the price of a new unit | Replace (Rheem and Bradford White use the same 50% guide) |
Most tank water heaters in Houston last 8 to 12 years, and sediment from our hard water shortens that. Rheem says the risk of leaks and sudden failure rises sharply after 10 years, and Bradford White says a leaking or rusted tank cannot be fixed. If you are weighing a different type of heater, our tank vs tankless lifespan guide compares them.
If the tank has to go, a replacement with Repipe Solutions usually costs $1,850 to $2,950 installed for most Houston homes. That price covers the new tank, the parts code requires, and taking the old one away. Because 40 and 50 gallon tanks are kept in stock, a leaking tank can usually be swapped out the same day.
Preventing the Next Leak
- Check the drain pan. Code requires a pan wherever a tank leak would cause damage, such as an attic or upstairs closet. It must be at least 1 1/2 inches deep with a drain of at least 3/4 inch (Texas IRC P2801.6). Make sure the pan drain is clear and ends somewhere you will notice water. Every tank we install gets a new pan and connections.
- Follow a maintenance schedule. The Department of Energy suggests flushing a quart of water from the tank every three months, checking the T&P valve every six months, and inspecting the anode rod every three to four years.
- Set the temperature to 120 degrees. The CPSC urges all users to set water heaters to 120 degrees to prevent scalds, and a lower setting also keeps the relief valve further from its limit.
Running short on hot water too? See why hot water runs out fast.
When to Call a Plumber
- Water is coming from the tank body or under the jacket
- The relief valve is discharging, or a new valve still drips
- You smell gas, or water is reaching the burner or wiring
- The leak is in an attic or upstairs, or the pan is full or overflowing
- A fitting still leaks after a gentle tightening
- The heater is 10 or more years old and leaking from anywhere
Frequently Asked Questions
Can a leaking water heater tank be patched or sealed?
No. A.O. Smith says leaking tanks cannot be repaired.
Why is there water in my water heater pan but no visible leak?
Check the relief valve discharge pipe first, because it often empties into the pan. On a gas unit, condensation is the other common cause. If neither explains it, have the tank checked.
Is it normal for the relief valve to drip a little?
No. A properly working relief valve stays closed. A drip means the valve is worn or the tank is reaching too much pressure or temperature, often from thermal expansion.
Why is my brand new water heater leaking?
Usually it is a connection that needs attention, or condensation. A.O. Smith notes newer, more efficient gas heaters condense more than older ones. If water is coming from the tank body on a new unit, shut it down and call the installer right away.
Should I drain a water heater that is leaking from the bottom?
If the tank itself is leaking, draining it limits how much water reaches the floor. The water comes out hot, so run a hose to a floor drain or outdoors, and keep children and pets away. If you are unsure, shut off the power and water and let a plumber drain it.
Water Heater Leaking in Houston?
Repipe Solutions finds the source of the leak, repairs the valves and fittings that can be repaired, and tells you straight when the tank has gone. Quotes are free with no trip charge, and in most cases we can replace a failed tank the same day. See our tank water heater replacement in Houston or contact Repipe Solutions to schedule a visit.
Featured photo: “Water Heater Thermostat” by Mark Florence via Openverse, licensed under CC BY-SA 2.0, converted to WebP and shared under the same license.