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Quick answer
Water at the bottom of a water heater is either a fixable part, such as a loose drain valve or a relief valve discharging, or the tank itself, which A. O. Smith says usually means replacement when it has corroded. [1] First turn off the power or gas, then close the cold water valve on the heater. [1] Dry the tank and floor and watch where new water appears. Get the area dry within 24 to 48 hours to keep mold from growing. [8]
Do this first: make it safe and stop the water
A. O. Smith, a water heater maker, says a leaking water heater should be treated as urgent: turn off the power or gas, then the water supply. [1] Go in this order.
Check for electricity near the water. If water is near outlets, cords or the panel, do not enter the water. Turn power off at the panel only if you can reach it from a dry spot; otherwise call the utility or an electrician. CDC says not to enter standing water to reach the main power switch; call an electrician instead. [2]
Electric heater: switch off its breaker at the panel. [1]
Gas heater: if you are confident doing so, turn the gas shut-off valve near the heater to off. [1]
Close the shut-off valve on the cold water line leading into the heater. [1] If it will not turn or the water keeps coming, close the main water shutoff for the house.
Do not open the drain valve or lift the relief valve lever while the tank is hot. The water inside can be scalding; Rheem's manual warns that water over 125°F can cause severe burns instantly. [3]
Move boxes and anything stored near the heater out of the water.
Take photos and video of the heater, the water and anything damaged before you clean up. [4]
If you smell gas
Rheem's gas water heater manual says not to try to find the cause yourself, not to light any appliance, not to touch any electrical switch and not to use any phone in the building. Leave the house right away with your family and pets, leave the doors open, and call the gas supplier from a neighbor's phone, or the fire department if you cannot reach the supplier. Do not return until the gas supplier or fire department says it is safe. [3]
What a leak at the bottom usually means
A. O. Smith says puddles or damp spots near the heater are clear signs it is leaking, and that closer inspection may show the leak is coming from the tank itself or from loose plumbing connections. [1] So a puddle at the base does not by itself prove the tank has failed. Dry the tank, the pipes above it and the floor with towels. Then watch for a few minutes, with a flashlight, to see where water shows up first.
Where the water shows up on a tank water heater, and what it usually means
Where you see water
Likely cause
Usually
Pipe fittings and connections on top
Loose pipe connections from thermal expansion or wear
Tighten or replace the fitting
The relief valve on the side, or its discharge pipe
Too much temperature or pressure, or a faulty valve
Find the cause; a broken valve is replaced
The drain valve, low on the front of the tank
A loose or faulty drain valve
Tighten or replace the valve
Drips on a gas heater after cold water fills it or the burner first fires
Condensation
Temporary and not a cause for concern
The base of the tank itself
A corroded or cracked tank
Replace the heater
The floor is wet but the heater is dry
Another source nearby
Check pipes overhead and nearby appliances
Table sources: A. O. Smith's leak guide [1] and Lennox on relief valves. [5] The last row is a practical check, not from either source.
Drain valve, relief valve or tank: how to tell
Drain valve. The drain valve sits near the bottom of the tank, so its leaks look like a bottom leak. A. O. Smith says a loose or faulty drain valve can leak, and this is usually fixed by tightening the valve or replacing it if it is beyond repair. [1] If water drips from the spout, the valve is not sealing. If water seeps around the threads where it meets the tank, have a plumber look at it.
Temperature and pressure (T&P) relief valve. Lennox says the T&P valve opens and releases water when tank pressure reaches 150 psi or the water reaches 210°F. Occasional dripping can be normal, most often in closed plumbing systems with no expansion tank, but continuous leaking points to a thermostat problem, thermal expansion, sediment or a valve that needs replacing. [5] A. O. Smith's 2012 installation manual for one of its heat pump water heaters says the relief valve's discharge line should end no more than six inches above a floor drain, or outside the building, so water from it can end up near the base too. [6]
Never cap or plug the relief valve
The same manual says that if the T&P valve is dripping or leaking, have a qualified person replace it, and warns: do not plug the valve and do not remove it, because failure to follow these instructions can result in death or explosion. [6] If the valve fails to reset and keeps releasing water after it is tested, it says to immediately disconnect the power, close the cold water inlet valve and call a qualified person.
Condensation. A. O. Smith says gas heaters may form condensation when cold water enters the tank or when the burner fires after sitting idle, and that this is typically temporary. On electric heaters it is normal and usually clears as the tank warms up. [1] Drips that stop as the tank heats up fit that pattern. A puddle that keeps growing is a leak.
The tank. A. O. Smith says water coming from the base of the heater is often the first sign of a serious problem, such as a corroded tank, and that replacing is usually more practical and cost-effective than repairing. [1] Corrosion from hard water minerals cannot be repaired, and a cracked tank typically means a full replacement. [1] Its installation manual puts it plainly: due to the normal corrosive action of the water, the tank will eventually leak after an extended period of time. [6]
Warning signs that point to the tank: rust, cloudiness or a metallic smell in the water, which can indicate sediment or corrosion inside the tank, and rumbling or popping, which usually means sediment has built up in the bottom of the tank. [1]
Age: A. O. Smith says water heaters typically last 8 to 20 years depending on the type, and that replacing an old unit is usually more cost-effective than repairing it. [1]
Safe to do yourself
With power and water off, gently tightening a leaking pipe fitting with a wrench, without over-tightening, is a reasonable DIY step, as A. O. Smith describes. [1] So is making sure the drain valve is fully closed. Replacing a T&P valve involves draining the tank, and A. O. Smith says to call an authorized professional if you do not feel confident fixing the problem yourself. [1]
Clean up the water before it causes damage
A storage water heater holds 20 to 80 gallons, according to the U.S. Department of Energy, and DOE explains that cold water enters the tank to replace the hot water that leaves, ensuring the tank is always full. [7] That means a leaking tank keeps drawing in water until you close the cold water valve. In a basement or a closet next to finished rooms, that water reaches carpet, baseboards and drywall fast.
With the water valve closed and the power off, use a wet/dry vacuum, mops and towels on the standing water.
Pull up wet rugs and carpet and move furniture out of the area.
Check the walls near the heater. Press the drywall and baseboards; soft or swollen spots soaked up water.
Run fans and a dehumidifier once the electrical side is safe. EPA recommends keeping indoor humidity below 60 percent, ideally 30 to 50 percent. [8]
Aim to have everything dry within 24 to 48 hours. EPA says that in most cases mold will not grow if wet materials are dried in that window. [8] The Massachusetts quick reference says to cut out and discard wallboard that has not been sufficiently dried within 48 hours. [9]
Repair or replace, and what it costs
A drain valve, a fitting or a T&P valve is a repair. A leaking tank is a replacement. Angi's water heater cost guide, updated July 20, 2026, puts tank heater repairs at $100 to $500. It lists tank-style replacement at $882 to $1,826, averaging $1,348, and tankless systems at $1,400 to $3,900. [10] Angi says the heater's size and type drive the price, to budget for permits, gas line work, electrical upgrades and removal of the old unit, and that labor is usually about half the total. [10]
Cleanup of the water that got out is a separate bill. See the water damage restoration cost guide for current figures.
Prevention for the next heater. The Department of Energy says routine maintenance may include 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; follow your owner's manual. [7] A. O. Smith says anode rods usually last 3 to 5 years. [1] Its heat pump installation manual also calls for a suitable metal drain pan under the heater, piped to an adequate drain, to help protect the property from condensate or leaks in the piping connections or tank. [6]
Will insurance cover a leaking water heater?
Often the water damage is covered and the heater is not. The Insurance Information Institute lists accidental discharge of water from a household appliance among the perils covered by common policy types such as the HO-3. [11] NerdWallet's June 2026 guide says a homeowners policy would likely cover water damage from a water heater that springs a leak, if it was properly maintained, but would not pay to fix or replace the heater itself unless you added equipment breakdown coverage. [12]
Gradual leaks are treated differently. Washington's insurance commissioner says homeowner insurance usually covers sudden leaks but may not cover gradual ones. [13] The Insurance Information Institute says policies will not cover damage due to lack of maintenance. [11] Your own policy decides, so read its water damage and exclusion sections or ask your agent.
Photograph the heater, its label and the damage before cleanup. [4]
Keep the old heater and damaged items until the adjuster has seen them. [4]
Ask the plumber for a written note on what failed and why.
Save receipts for the plumber, fans, dehumidifiers and any emergency work.
Common questions
Is a water heater leaking from the bottom an emergency?
Treat it as urgent. A. O. Smith says a leaking water heater requires immediate action: turn off the power or gas and the water supply, then find the source. It says a leak from the base of the heater is often the first sign of a serious problem, such as a corroded tank. [1]
Can a water heater leaking from the bottom be fixed?
It depends on the source. A leaking drain valve can usually be tightened or replaced. [1] If the tank itself is corroded or cracked, A. O. Smith says replacement is the usual answer. [1]
Is it normal for a water heater to drip a little?
Sometimes. A. O. Smith says gas heaters can form temporary condensation when cold water enters the tank. [1] A T&P valve may drip occasionally during heating, but Lennox says continuous leaking points to a problem. [5] A puddle that keeps growing is a leak.
Can I still use my water heater if it is leaking?
A. O. Smith says no. It says to turn off the power and water supply and have a professional diagnose and repair the problem before using the unit again, because even small leaks can cause significant water damage and mold conditions. [1]
How long do water heaters last?
A. O. Smith says 8 to 20 years, depending on the type. [1] DOE says periodic maintenance, such as flushing the tank and checking the relief valve, can significantly extend a heater's life. [7]
Does homeowners insurance cover a leaking water heater?
It may cover sudden water damage from the leak, but usually not the heater itself or damage from a gradual leak or poor maintenance. [12][13] Check your own policy.
