Short answer
If your water heater is leaking, protect people first. If you smell gas, get everyone out and call the gas company from outside. Otherwise turn off the power or gas as the label directs, shut the cold water valve on the heater, keep clear of any hot discharge and call a licensed plumber. Do not plug a relief valve. Take photos for your insurer.
A water heater leak can be a slow drip or a flood, and it can mean anything from a loose fitting to a failed tank. This guide covers safe first steps, where leaks come from, the one valve you should never cap, when to call at once and insurance basics. It draws on government, manufacturer and insurance-regulator sources, and your heater's label and manual come first.
To find your main shut-off, read how to shut off your water.
Water heater leak: what to do first
- If you smell gas, leave. One manufacturer's installation manual says to open the windows, get all people out of the building, avoid matches, appliances and electrical switches, and use an outside phone to call the gas company and the fire department. It says not to go back inside. Do this before anything else.
- Turn off the power or gas as the label directs. For an electric heater, turn off its circuit breaker, but only if you can reach the panel without standing in water. If you cannot, call an electrician or your electric utility. For a gas heater, follow the shut-off steps on the heater's label or manual, which typically involve the manual gas control valve.
- Shut off the cold water supply to the heater. A City of Scottsdale, Arizona water heater guide says a shut-off valve is required on the cold water inlet side of the heater. Closing it stops new water flowing into the tank. If it will not close, use the main shut-off for the house.
- Keep clear of hot water. Water from a leak or a relief valve discharge may be hot. The manual above warns that discharged water may be hot and can cause scald injuries.
- Do not touch wet electrical equipment. Stay out of standing water near outlets, cords, the panel or the heater's wiring.
- Protect the area. Move belongings away, put down towels or a bucket if it is safe and photograph the leak and damage before you clean up.
- Call a licensed plumber. Tell them what you see, where the water is coming from and what you have turned off.
Is it a leak, or is it condensation?
Not every puddle is a leak. The same manufacturer's manual says moisture from the products of combustion condenses on the tank surface and jacket of a gas water heater and forms drops of water. It says this condensation is normal and should not be confused with a leaking tank, and that it stops once the water reaches 120 degrees Fahrenheit and the tank warms up, usually in one to two hours.
If you cannot tell, treat it as a leak and have someone look.
Where water heater leaks come from
In general terms, leaks come from three kinds of places. Where the water appears points to the cause, but it is not proof, since water can run along a pipe or the tank before it drips.
- Pipe connections and fittings. The hot and cold water lines connect to the heater, and a loose or worn fitting can drip down the side. The manual mentions leaks in the tank and pipe connections as the reason to put a drain pan under the heater.
- Valves and ports. These include the temperature and pressure relief valve, the drain valve and the opening that holds the anode rod. The City of Scottsdale guide says plastic drain valves are common and cautions you to be careful not to break one. It also says the anode rod is screwed into the top of the tank.
- The tank itself. The Scottsdale guide says almost all components on a water heater can be fixed or replaced except for the tank, and that once the tank rusts through there is no way to repair it, so replacement is the only solution.
Our guide to how long a water heater lasts covers age and signs of wear. The Department of Energy says storage water heaters last 10 to 15 years.
Water heater leaking from the bottom
Water at the base has several possible sources: condensation, a leaking drain valve, a dripping relief valve discharge pipe or water running down from a fitting above. It can also mean the tank itself has failed. If the water is coming from the tank body, expect a talk about replacement, because the Scottsdale guide says a tank cannot be repaired once it rusts through.
What you can do safely is limited. Shut off the power or gas and the cold water as above, dry the area and see whether water returns. Ask the plumber to show you where the water is coming from and to explain why a repair will or will not hold.
Water heater leaking from the top
A leak at the top may start at the hot and cold water connections, the relief valve or the anode rod port. These parts can sometimes be repaired or replaced without replacing the heater, unlike a failed tank. Do not take apart a fitting yourself on a hot, pressurized heater, since the water can scald. If water runs down a pipe at the side of the heater, it may be the relief valve discharge pipe, covered next.
The relief valve: never cap or plug it
Every storage water heater has a temperature and pressure (T&P) relief valve. A San Diego County housing inspection page explains that without a working T&P valve a water heater can explode, causing property damage, severe injury or death, and that the valve lets water or steam escape if the water gets too hot or the pressure too high. It says the valve opens at 150 pounds per square inch or 210 degrees Fahrenheit, and that thermostats do not replace it. Washington State's rule on relief valves gives the same two figures and requires full-sized drains that exit downward and are not threaded at the outlet.
One manufacturer's manual is direct about what not to do. It says the discharge line must not be capped, blocked, plugged or contain any valve between the relief valve and the end of the line, and says not to plug the valve itself.
A dripping relief valve is a problem for a plumber to diagnose, not a thread to cap. The same manual says periodic discharge may be due to thermal expansion in a closed water supply system, where heated water expands and raises the pressure, and recommends an expansion tank or a relief valve on the cold supply. Ask the plumber whether that applies to your home.
The manual says to operate the valve by hand at least once a year, standing clear because the water may be hot, and the Department of Energy lists checking it every six months among routine storage heater maintenance. If the valve does not reset and keeps releasing water, the manual says to immediately shut off the manual gas valve and the cold water inlet valve and call a qualified service technician.
Hot water and scalds
The US Consumer Product Safety Commission's Avoiding Tap Water Scalds sheet warns that most adults will suffer third-degree burns if exposed to 150 degree water for two seconds, 140 degree water for six seconds or 130 degree water for thirty seconds. It urges users to lower their heaters to 120 degrees Fahrenheit. For a leak, treat any water near the heater as potentially scalding.
When to call right away
Call a plumber at once, and the gas company or emergency services where noted, if you see any of the following:
- You smell gas. Leave, then call the gas company and the fire department from outside.
- Water is spraying or flowing steadily and shutting the cold water inlet does not stop it.
- The relief valve keeps releasing water or steam and does not reset.
- Water is near electrical equipment and you cannot turn off the power safely.
- The leak is from the tank itself.
- Water is spreading to finished floors or a lower level, where damage grows quickly.
A small drip from a fitting is less urgent, but still call a plumber the same day and keep the cold water to the heater off until it is looked at. See also water heater not heating and low water pressure causes.
Repair or replace?
A plumber can usually repair a failed fitting or valve. For a tank that has leaked through, the Scottsdale guide says replacement is the only solution. The same guide says replacing sacrificial anodes every three to four years adds considerable life to a heater, which helps before a tank fails, not after.
Ask for the cause of the leak in writing. Our water heater size calculator and tankless vs tank guide help you plan a replacement.
Insurance basics for a water heater leak
Insurance rules differ widely, so this page does not say what any policy covers. General points from public sources:
- Call your insurer or agent promptly. The California Department of Insurance's residential property claims guide says to report damage to your agent or company representative to start the claim process.
- Protect the property. The same guide says to make temporary repairs to prevent further damage, and to save receipts for materials you buy. Shutting off the water to the heater is a form of this.
- Photograph and list the damage. It advises recording damaged items with brand names and model numbers where possible.
- Do not throw out damaged items until the adjuster says so, and hold off on extensive permanent repairs until the adjuster has inspected.
An article from the National Association of Insurance Commissioners, dated February 8, 2024, says homeowners policies cover damage from a sudden and accidental discharge from a plumbing system, but that damage may not be covered if the insurer finds the homeowner neglected the plumbing. Whether a water heater leak is covered, and whether the heater itself is, depends on your policy, so ask your insurer before cleanup begins.
Preventing the next leak
- Look at it monthly. The Scottsdale guide recommends a visual check at least once a month.
- Use a drain pan. The manual recommends a drain pan under the heater, piped to an adequate drain, to protect the area from leaks.
- Follow the maintenance in your manual. The Department of Energy lists flushing a quart of water from the tank every three months, checking the relief valve every six months and inspecting the anode rod every three to four years, depending on model. See how to flush a water heater.
- Know your valves. Find the heater's cold water shut-off and your main shut-off before you need them.
What to look up where you live
- City or county building department. Many places require a permit for a water heater replacement. Ask what applies and whether discharge pipe rules differ locally.
- State or provincial plumbing or contractor licensing board. Confirm a plumber's licence and check for complaints.
- Your insurer or your state or provincial insurance regulator. Ask what your policy says about water damage and what documents they need.
Note for Canadian readers: provinces and municipalities set plumbing, permit and insurance rules, and claims are in Canadian dollars. Natural Resources Canada's Water Heater Guide notes that new water heaters must have a temperature and pressure relief valve. Check the current rules for your province.
For plumbing company owners
Water heater leaking is an urgent search, made from a phone with water already on the floor. The company that answers and is easy to find usually gets the call. See emergency plumber marketing and plumbing answering service, or book a call with LiveLeadsLane. LiveLeadsLane is a marketing practice for contractors, not a directory, and it does not take jobs or refer homeowners.
