First, make it safe
Shut off the heater's fuel first. On an electric unit, switch off its breaker at the panel. On a gas unit, turn the gas control to off. If you smell gas, leave the home right away, do not touch switches and call your gas utility or 911 from outside.
Then close the cold water supply valve on the pipe entering the top of the tank. If water is spreading toward electrical outlets, avoid walking through it until the power in that area is off.
- Switch off the electric breaker or turn the gas control to off.
- Close the cold water shutoff valve above the tank.
- Open a hot faucet in the home so pressure drops and the leak slows.
- Move belongings, rugs and boxes away from the water.
- Take photographs of the leak and the damage for your records.
- Call a plumber to inspect before turning anything back on.
Where is the water coming from?
Dry the area with towels, then watch for the first drip. The location tells you a great deal. Water rarely comes from where it first appears on the floor, so look up the tank and its fittings.
The top connections
Drips on the supply lines or shutoff valves are usually a loose or worn fitting. These are repairable.
The relief valve or its pipe
Water from the discharge pipe means the valve is opening because of pressure or temperature, or it is worn. Do not cap it.
The drain valve at the bottom
A slow drip from the spigot can be a worn valve washer, an easy fix, or a sign of sediment holding it open.
The tank shell or base
Water seeping from the tank body or through the jacket means the steel has corroded through. The tank cannot be repaired.
Why tanks leak
A steel tank is lined with glass, and inside it an anode rod corrodes first to protect the steel. When the rod is used up, the tank itself starts to rust. Rust spreads until a pinhole opens, and the leak grows from there.
Sediment accelerates the process. Minerals settle at the bottom, trap heat and stress the lining. Pressure that is too high in the home's plumbing also shortens a tank's life, which is why an expansion tank matters on closed systems.
Repair or replace?
| What leaks | Usually means | Typical path |
|---|---|---|
| Supply line or shutoff | Worn fitting | Repair |
| Relief valve or pipe | High pressure or worn valve | Test, replace valve, check expansion |
| Drain valve | Worn valve or debris | Repair or replace valve |
| Tank body | Corroded steel | Replace the water heater |
| Heating element gasket, electric | Failed seal | Repair when the tank is sound |
The water heater repair page explains these repairs. If the tank body is the source, the water heater replacement page covers what a replacement involves.
Water on the floor right now?
Call the 24/7 line. A dispatcher sends a licensed plumber and tells you what to do while you wait.
Limiting the damage
- Use a wet vacuum or towels to remove standing water within hours, not days.
- Run fans and open windows if the weather allows to dry flooring and walls.
- Check cabinets, drywall and baseboards near the heater for soft or discolored spots.
- Keep the heater off until a plumber has inspected it.
If water reached drywall, flooring or insulation, ask your insurer what documentation they want. Photographs taken before cleanup help.
Watch for the slow signs of moisture over the next week. A musty smell, bubbling paint, a soft baseboard or a stain that spreads after it dries all mean water got further than you could see. Moisture trapped behind a wall can grow mold, so dry the area thoroughly.
If you rent, tell your landlord right away and keep a copy of your photos. If you own, keep the receipt for the repair and any drying equipment, since your insurer may ask for both.
Garage, closet and attic locations
A heater in a garage often sits on a slab, so water runs to a floor drain or the driveway. A closet heater can soak adjacent walls and flooring before anyone notices. An attic heater is the worst case, because water drops through the ceiling below.
A drain pan with a pipe to a safe place gives early warning in any of these locations. Ask your plumber whether a pan or a leak sensor suits your layout.
Water heater leaks and Sanger conditions
Sanger water is hard. The city's 2024 water quality report lists hardness averaging 145.5 ppm, with readings up to 330 ppm. Hard water leaves scale on heating elements and the tank bottom, which makes heaters work harder and can shorten their life. A tank that has never been flushed in a hard water home tends to have heavy sediment.
Hot valley summers also matter. Fresno-area July highs average near 98 degrees, and a heater in an uninsulated attic or garage works in a hot room. Heat adds stress to fittings and the relief valve. If your unit is more than about a decade old, have it checked before a leak finds it for you.
What to expect from the plumber
The plumber identifies the source, tests water pressure and checks the relief valve. If the tank body leaks, you hear that replacement is needed and you see the options. If a fitting is the cause, the repair is usually fast.
Homeowners in Parlier and Fowler get the same visit. If the leak is not the heater, a leak somewhere else in the wall can mimic it, and leak detection finds hidden water lines.
Codes and sourcesCodes behind this advice
The UPC-based California Plumbing Code requires a relief valve with a drain, and California Health and Safety Code section 19211 requires bracing. A plumber checks both during a leak call.
FAQLeaking water heater questions
A body leak can release a full tank of water quickly, so treat it as urgent. Shut off the fuel and the cold supply, then call.
No. A small tank leak tends to grow. A leak at a fitting may be safe for a short time with the unit off, but have a plumber inspect it.
High pressure, high temperature or a worn valve can cause it. Do not plug the valve. Have a plumber test it.
Coverage depends on your policy and the cause. Ask your insurer, and keep photographs and the plumber's invoice.