What Causes a Water Heater to Leak at the Bottom?

All water heater tanks have a glass or porcelain lining to protect the steel from rust. Over years, this lining can crack or wear thin, allowing water to contact the bare metal. Once corrosion starts, it creates a pinhole that expands. This type of leak from the tank body usually means the entire unit needs replacement.

Water pooling at the base can sometimes be traced to the temperature and pressure relief valve system. This safety valve opens if temperature or pressure gets dangerously high. The water it discharges runs down a pipe that terminates near the floor. If this pipe is dripping or the valve is leaking, it creates the illusion of a tank leak. This is a critical safety issue needing immediate attention.

• The Temperature and Pressure (T&P) valve is a safety device on the side of the tank.
• It has a discharge pipe that runs down the side of the heater to the floor.
• If the T&P valve is faulty or the pressure is too high, it releases water.
• This water runs down the pipe and can pool at the heater's base.
• This looks like a bottom leak but originates higher up.
• A plumber should check the valve and your home's water pressure.

Safety is your first priority when you discover a leak. Shut off the power or gas to prevent electrical hazards or gas issues. Then, locate and close the cold water inlet valve to stop the water supply. Draining the tank can reduce pressure and slow the leak. Place buckets and towels to manage water until you get professional help.

• Turn off the power to an electric heater at the circuit breaker.
• For a gas heater, turn the gas control knob to the 'Pilot' or 'Off' setting.
• Find the cold water supply valve on top of the heater and turn it off.
• Connect a garden hose to the drain valve and run it to a floor drain or outside.
• Open a hot water faucet in your home to relieve pressure in the pipes.
• If the leak is severe, use towels and a bucket to contain the water.