My water heater is leaking from the bottom. What do I do right now?

There is water on the garage floor, or worse, the carpet outside the hall closet is damp and the water heater is on the other side of the wall. Tank water heaters do not announce a failure. They weep at the base for a few weeks, and then the bottom of the tank lets go. The first ten minutes are about stopping the water and the power. Everything after that is about the room, and then the replacement.

Take these steps in order. None of them need tools beyond a flashlight.

Step one: close the cold water supply

Find the two pipes on top of the tank. One is the cold inlet, and it has a valve on it: a lever handle you turn a quarter turn until it sits across the pipe, or a round handle you turn clockwise until it stops. Close it. This stops the tank from refilling as it drains out the bottom, which is what turns a slow leak into forty gallons on the floor.

If the valve is stuck or breaks off in your hand, which happens with older gate valves in a humid garage, close the main shutoff for the house instead, at the front wall near a hose bib or in the meter box by the street. No water anywhere in the house beats water on the floor.

Step two: shut off the power or the gas

Electric heater: go to the panel and switch off the breaker labeled for the water heater, a double-pole breaker with two handles joined together, usually 30 amps. Do not skip this. If the water level drops below the upper element with the power on, the element burns out in seconds, and a live 240 volt appliance standing in a puddle is its own hazard.

Gas heater: turn the gas control knob on the front of the burner assembly to Off, and if there is a shutoff valve on the gas line near the tank, close it too. If you smell gas at any point, leave the area, do not flip any switches, and call the gas company from outside. Then call us.

Make sure the leak is really from the bottom

Water on the floor under a heater has four common sources, and only one of them means the tank is done.

• A fitting on top. The cold inlet, the hot outlet, or a flex connector can drip and run down the jacket to the base. Dry the top of the tank, wait, and watch.
• The temperature and pressure relief valve. It is on the side or top, with a pipe running down toward the floor or the pan. If the water is at the end of that pipe, the valve is discharging, which is a different problem and often a repair.
• The drain valve. The small spigot near the bottom of the tank can drip if it was opened once and never sealed again.
• The tank itself. Water seeping from under the outer jacket, from the seam at the base, or from beneath the tank with everything above it dry. This is the one.

A fitting, the relief valve, or the drain valve is a repair, and the tank may have years left. If it is the tank, keep reading.

Why a tank leaking from the bottom is finished

The steel tank inside the jacket is lined with glass, and the lining cracks and wears over time. The anode rod slows corrosion until it is used up; after that the steel goes. Hard water, which is most of Lee and Collier County and worse on well water, leaves a bed of sediment on the bottom of the tank. The burner or the lower element cooks the steel under that sediment every day, and the bottom is where the tank rusts through first.

There is no patch for that. A leak from the tank body means the pressure vessel has failed, and the hole only gets bigger. The unit is replaced.

Protect the floor and the room

• Check the pan. Most heaters installed in the last few decades sit in a drain pan with a line to the outside or to a floor drain. If the pan is doing its job, the water goes outside. If the pan is full and not draining, the line is clogged; bail it with a cup or a wet vac.
• Move things away. Anything on the floor near the heater, storage boxes, paint cans, the hurricane supply bin, goes somewhere dry now.
• An interior closet is a bigger deal. In a garage, water runs to the door. In a hall closet or a laundry room, it goes under the baseboard and into the drywall and the flooring on the other side of the wall. Pull the baseboard if it is wet, get a fan on it, and check the next room for damp carpet or lifting laminate. In our humidity, drywall that stays wet more than a day or two can start growing mold, and a large soaked area may mean a water damage contractor and a call to your insurer.
• Photograph everything before you clean up. Insurers ask.

Why replacement is a licensed, permitted job

In Florida, replacing a water heater is permitted work even when the new one is the same size in the same spot. The permit exists because the things that make a water heater safe are the things a rushed swap skips: the pan and its drain, the relief valve and its discharge line, the expansion tank where the house has a backflow preventer or pressure regulator, and the electrical or gas connection. The inspector checks each one.

A licensed plumber pulls the permit, sets the new unit to current code, and schedules the inspection. An unpermitted swap has a way of surfacing later, at a home sale, during a 4-point insurance inspection, or in a claim after the next leak.

Once the water and power are off, the emergency is over. Send us a photo of the heater and its label and tell us where it sits, and we can talk through what replaces it. If you are looking at water on the floor right now, call. A plumber answers 24 hours a day.