Water Heater Repair
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Plumbing guide
Water Heater Leaking From the Bottom: What It Means
Water on the floor under a water heater is a warning, but not always a death sentence. Finding where it comes from tells you whether it is a repair or a replacement.
By the Urban Comfort Plumbing team ·
Do this first
Shut off the cold water supply to the heater. The valve is on the pipe that enters the top of the tank, usually with a handle or a wheel. Turn it clockwise until it stops. Then cut the energy: switch off the breaker for an electric heater, or turn the gas control to off for a gas heater.
If the water is spreading into rooms or near outlets, shut off the main water valve for the house too. Mop up the water. Standing water on a garage or closet floor can soak into walls and flooring, and moisture invites mold. If you smell gas, leave the house and call the gas utility from outside.
Find out where the water is really coming from
Dry the tank and the area around it, then watch. Many leaks that look like they are from the bottom start higher up and run down. Check the pipe connections at the top, the relief valve, the drain valve near the bottom and the heating element or burner access panels.
Condensation is a common false alarm. A gas heater can drip from the burner area when it first fires up in a cold space, because the flue gases condense. That usually stops after a few minutes and is not a leak. A steady drip or a puddle that returns after you dry it is a real one.
Leaks that are repairable
A loose or corroded pipe connection can be tightened or replaced. A leaking drain valve at the bottom of the tank, the little spigot used for flushing, can be replaced, though a corroded tank wall around it complicates it. The temperature and pressure relief valve, which has a pipe running down toward the floor, may leak if it has worn out or if the pressure is too high. A new valve is an inexpensive part, but a valve that opens because of excess pressure points to another problem, such as a missing expansion tank.
A leak from the heating element gasket on an electric tank can often be fixed by replacing the gasket. These repairs are described under water heater repair.
Leaks that mean a new heater
If water is seeping through the tank jacket or from the seam at the bottom, the steel tank has failed. Over time, sediment and corrosion eat through the inner lining. The anode rod, a sacrificial piece of metal inside the tank, is meant to corrode first and protect the steel. Once it is used up, the tank itself corrodes. A leaking tank cannot be patched.
Age is a clue. A tank that is ten years old or more and leaking from the body is a replacement. See water heater replacement for what a good installation includes, and ask about the drain pan and the discharge line to the outside.
How a tank water heater works
A tank heater is a steel tank wrapped in insulation and a metal jacket. Cold water enters through a dip tube that sends it to the bottom, where an electric element or a gas burner heats it. Hot water, which rises, is drawn from the top. A thermostat controls the heat, and the relief valve opens if pressure or temperature climbs too high.
The tank is lined with glass to protect the steel from water. Heating and cooling cause the tank to expand and contract, and over the years the glass lining can crack, which lets water reach the steel. That is why every tank eventually fails, usually at the bottom, where sediment sits and holds moisture against the steel.
Gas and electric: what differs when it leaks
On an electric heater, a leak near the bottom may come from a lower heating element gasket. Turn off the breaker before touching anything, since the elements carry power. On a gas heater, water can drip onto the burner and put out the pilot, and a gas heater that has been flooded must be checked before relighting.
Whichever type you have, never relight a gas pilot if you smell gas, and never run an electric heater with the tank empty. An empty tank burns out the elements within minutes.
Questions to ask before you replace it
Ask what size fits your household and why. Ask whether a drain pan, an expansion tank and a new relief line are included. Ask about the warranty on the tank and on labor. Ask whether a permit is needed and who pulls it. Ask where the old tank goes, and whether the price includes removal.
If the heater is in a garage, ask about securing it and raising it according to the code that applies. Also ask whether a tankless or heat pump model makes sense for your house. See tankless service for what a tankless unit needs.
How long a tank should last
Most tank heaters last somewhere around ten years, and the range runs shorter or longer with water quality, sediment and how well the tank was maintained. Flushing the tank each year and checking the anode rod every few years can extend its life. If yours is near or past the ten-year mark, a leak is the tank telling you it is time, and planning the replacement is better than waiting for a flood.
Limit the damage
A drain pan under the tank, piped to the outside, catches small leaks and gives you an early warning. Many codes require one when the heater sits above living space or in certain locations. A water leak sensor on the floor beside the tank is a low-cost alarm.
If the area has been wet for a while, dry it quickly with fans and a dehumidifier, and watch for a musty smell. A bigger leak that soaked drywall or flooring may need water damage restoration to dry the structure.
Common questions
Leaking water heater questions
It can be. Water and electricity are a bad mix, and a gas heater adds a gas risk. Shut off the water and the power or gas, then call.
No. A leak from the tank body means the steel has failed. Fittings and valves can be repaired, but the tank cannot.
The valve opens when pressure or temperature is too high. It may be worn, or the system may need an expansion tank. Have it checked right away.
A tank leak gets worse and can flood a room. Shut off the water to the heater and arrange a replacement as soon as you can.
Related services
Water Heater Installation & Replacement
Replace a failed tank heater and choose the right size, fuel and location.
Water Damage Restoration
Dry out and restore a home after a leak, burst pipe or storm water.
Water heater leaking now?
Shut off the water to the heater, then call the 24/7 line.