Leaking Water Heater: Repair or Replace Cost

Where the water comes from decides the cost. A leak at a valve, fitting or pipe connection is a repair. A leak from the tank itself means the tank has corroded through, and the only fix is a new water heater.

Repair vs. replacement prices

Where leaks usually start

• Temperature and pressure relief valve. Water from the discharge pipe can mean a faulty valve or pressure that is too high. A new valve costs $50 to $300 installed (HomeGuide). See pressure relief valve replacement cost.
• Drain valve. HomeGuide includes tightening or replacing a drain valve within its $100 to $1,000 leak repair range.
• Supply line connections. Loose or corroded fittings at the top of the tank.
• The tank body. Water seeping from under the jacket or pooling under the unit points to a failed tank. Angi says a replacement is needed if water pools under the unit.

What to do right away

1. Shut off the cold water supply valve to the heater.
2. Turn off the gas control (gas units) or the breaker (electric units).
3. Contain the water and keep it away from flooring and walls.

Costs of waiting

A slow leak can turn into a flood. Angi reports that repairing water damage averages $1,300 to $5,550, more than the cost of a new water heater. If you need a plumber at night or on a weekend, see emergency water heater repair cost.

Find where the water is coming from

The fix depends entirely on the source of the leak, so the first step is to dry the area and look:

• Top of the tank: loose or corroded supply connections, or a leaking inlet or outlet nipple. Usually a simple repair.
• Relief valve or its discharge pipe: the valve may be worn, or it may be opening because temperature or house pressure is too high.
• Drain valve at the bottom: a dripping drain valve can often be tightened, capped or replaced.
• Bottom of the tank, with no other source: this is usually the tank itself rusting through from the inside. That cannot be repaired.

What affects the price

Parts like valves and fittings are inexpensive, so most of the cost of a fitting or valve repair is labor and the service call. If the leak turns out to be the tank, the job becomes a replacement and the price changes completely. An emergency call outside business hours adds to either.

More on what to do right away

1. Turn off power (electric) or set the gas control to off.
2. Close the cold water supply valve.
3. If the tank is leaking, drain it through the drain valve to a safe spot.
4. Check whether water has reached flooring, drywall or the ceiling below.

When replacement is the better value

If the tank is old, has a lot of sediment, or has already had other repairs, a leak is often the signal to replace it. Paying for a valve repair on a tank that will soon fail rarely makes sense.

Preventing leaks

Flushing the tank to remove sediment, checking the anode rod, and keeping house water pressure in a normal range all help a tank last longer. An expansion tank on a closed system reduces pressure swings that stress the tank.

In Texas

Hard water across much of Texas speeds up sediment buildup in tanks. In attic installations, a drain pan piped to the outside is the best protection against a slow leak turning into ceiling damage.

Leaks that look worse than they are

Not every puddle means the tank is done. Condensation can form on a cold tank when warm, humid air hits it, especially just after a large draw of cold water. A gas heater can also drip condensation from the burner area for a short time when it first fires. If the puddle appears only after heavy use and dries up, condensation is the likely cause.

A dripping relief valve discharge line usually points to high water pressure, thermal expansion or a worn valve, not a failed tank. A drip at the drain valve can often be stopped with a cap or a new valve. Leaks at the top of the tank are usually fittings or connectors, which are repairable.

Leaks that mean replacement

• Water seeping from under the tank jacket or from the bottom of the tank.
• Rust stains running down the side of the tank.
• Visible corrosion on the tank itself.

Once the inner tank has corroded through, no repair will last. The water will keep coming, and the leak can get worse quickly.

Protecting the floor

For a heater in a garage, a simple drain pan catches small leaks. In attics, closets and upper floors, a pan with a drain line or a leak sensor that shuts off the water automatically can prevent a ceiling collapse or floor damage if the tank fails. These are inexpensive compared with the damage they prevent.

What to tell the plumber when you call

Say where the water appears to be coming from, the age of the heater if you know it (it is often on the label as part of the serial number), and whether it is gas or electric. This helps the plumber bring the right parts and give you a better idea of cost up front.

Rental and warranty questions

If you rent, the landlord is usually responsible for repairing or replacing the water heater, so report the leak in writing right away. If you own the home, check the heater's label and paperwork before paying for a repair. Tank warranties often cover the tank itself for a set number of years, and a manufacturer may supply a replacement tank even if you still pay for labor. Some home warranty plans also cover water heaters, with a service fee per visit.