When water collects under a water heater, the first question is where it is coming from. A leak at a fitting is a small repair. A leak from the tank body is the end of the heater. You can tell the difference with a flashlight, a dry paper towel and a few minutes, and knowing it makes the call to a plumber more useful.
This guide walks through the steps and the safe way to shut the heater down.
A leak is not always an emergency, but it can become one. A tank that slowly seeps may fail suddenly and release the full volume of the tank, which is 40 gallons or more, across the floor. Treat any steady leak as urgent, and a gushing leak as an emergency.
Shut it down safely
Do these first, in order:
- Turn the cold water supply valve on top of the heater clockwise to stop water entering the tank.
- For an electric heater, switch off its breaker so the elements do not burn dry.
- For a gas heater, set the gas control to pilot or off, unless you smell gas.
- If you smell gas, leave the building and call the gas utility or 911 before anything else.
- Open a hot tap in the house to relieve pressure if water is still leaking.
- Protect the floor with towels, move stored items and use a wet vacuum if the leak is large.
Do not touch a wet electric heater until the breaker is off. Do not relight a gas heater that has been in water.
Heater leaking right now? Call (973) 488-5410 and we will help you decide what to do next.
Call (973) 488-5410Where the water is coming from
| Where | What you see | Likely cause | Repair or replace |
|---|---|---|---|
| Top fittings | Drips at the inlet or outlet connections | Loose or corroded fitting | Repair |
| Relief valve | Water from the discharge pipe | High pressure or temperature, or a failing valve | Repair or valve replacement |
| Drain valve at the bottom | A drip from the small valve | Worn valve | Repair |
| Heating element gasket | Drip near an electric element | Failed gasket | Repair |
| Under the jacket | Water pooling with a wet side | Tank leak | Replace |
| Base with rust | Rusty stain around the bottom | Tank corrosion | Replace |
If you are not sure, wipe the heater dry, wrap dry paper towels around each fitting and watch which one gets wet first. A leak that starts at the top and runs down can look like a tank leak, so trace it carefully.
Why heaters leak
Tanks fail because of corrosion, pressure and scale. Inside the tank a rod sacrifices itself to protect the steel. When the rod is used up, the tank wall begins to rust. Scale on the bottom insulates the water from the burner or element, which overheats the steel and speeds failure.
High household water pressure stresses the tank and the fittings. A heater that runs near the end of its expected life is more likely to leak at any point.
Some leaks are not from the heater. A leak in nearby pipes, a dripping condensate line or a wet floor from a different source can drip onto a heater and mislead you. If the heater is dry on top and the water comes from a pipe overhead, call about the pipe. The leak detection page explains how plumbers find those.
Can a leaking tank be repaired
No. Once the steel wall has a hole, the tank cannot be patched in a way that lasts. Sealants and epoxy are temporary at best, and a patch can fail without warning. Replacement is the right answer, and the sooner you plan it, the less water damage you face. See water heater replacement for what that involves.
A leak at a fitting, valve or gasket is different. These are repaired by replacing the part, and the heater can often run for years afterward. The repair page lists the common fixes.
Water heaters and floods in Lodi
Lodi's basements take on water in major storms. After the remnants of Hurricane Ida in September 2021, CBS New York reported that many homes took on a devastating amount of water and entire sections of the city were under several feet of water. A Saddle Brook resident told the station that water reached his basement for the first time in 15 years.
A water heater that sat in floodwater needs inspection even if it lights afterward, because water can damage gas valves, thermostats and wiring. Do not relight it. Have a plumber check it first. If you are in Saddle Brook or Hackensack, where basements also take water, consider raising the heater on a platform.
After the leak: protect the house
Water damage grows fast. Take photos for your insurance claim, run fans and dehumidifiers and remove wet materials such as cardboard and carpet padding. Mold can start within a day or two. If the water spread under walls or into finished space, a restoration company can check for moisture. The plumber can show you where the water traveled.
Check the floor drain too. A heater placed near a floor drain can let water escape harmlessly, and a drain pan with a discharge pipe protects floors when no drain is nearby.
What decides the cost of fixing a leaking heater
- Source
- A fitting or valve repair costs less than a tank replacement.
- Fuel
- Gas heaters need venting and gas checks that electric ones do not.
- Access
- A tight closet adds labor.
- Damage
- Water damage to the area is separate from the plumbing repair.
Lodi Pro Plumbing gives the price for repair and for replacement before work starts, so you can choose.
Leak questions
Is it safe to leave a leaking water heater overnight?
Only if you have shut off the water supply and power or gas to the heater. A leaking tank can fail suddenly.
Why is water coming out of the pipe on the side of my heater?
That is the relief valve discharge pipe. Water from it can mean high pressure or temperature, or a failing valve. It needs a plumber's check.
Does a small leak always mean replacement?
No. A small leak at a fitting or valve is a repair. A leak from the tank body means replacement.
My Lodi basement flooded and the heater still lights. Is it okay?
Not necessarily. Flood water can damage controls and valves that fail later. Have a plumber inspect it before you rely on it.
Does homeowners insurance cover a leaking heater?
Insurance often covers sudden water damage but not the heater itself. Check your policy and keep photos and the invoice.
Code basis. Plumbing work in New Jersey follows the state plumbing subcode, N.J.A.C. 5:23-3.15, which adopts the 2021 National Standard Plumbing Code. Ask which permits apply to your job and confirm with the Lodi Building Department.