Water Heater Repair: What Can Be Fixed and What It Costs

What can be fixed, and what it costs

HomeGuide's 2026 cost guide puts a typical standard-tank repair at $150 to $700, with a national average of $455. Tankless repairs run higher, $300 to $1,300. Here's what the common parts cost with a plumber doing the work:

On top of the part, plumbers charge $45 to $150 an hour, and many add a $50 to $200 call-out fee. Our water heater repair cost page goes part by part.

What can't be fixed

A leaking tank. If water is coming from the tank body, not a fitting or valve, the inner lining has failed. HomeGuide notes a leaking tank usually means replacement, at $600 to $1,800. Patching it isn't a thing.

Two other cases mean a new heater. If an A.O. Smith gas heater's flammable vapor system has been tripped by fumes, the manual says the whole heater must be replaced. The same goes for a heater that sat in flood water. On some gas models the ECO (energy cut-off) is single-use, and when it trips the whole gas control has to be replaced by a qualified person.

Before you assume the worst, find where the water is coming from. Leaks from the drain valve, the relief valve or the pipe fittings on top are all repairable. Our water heater leaking guide walks through it.

Repair or replace?

HomeGuide's rule is to consider replacing if the heater is more than 10 years old or the repair costs more than half the price of a new one. Its lifespan figures are 8 to 15 years for a tank and 10 to 20 for tankless. That fits what plumbers see: a single part on a six-year-old tank is an easy yes, while a gas valve on a rusty fourteen-year-old tank is money spent on a heater that's about to leak anyway.

Check the age on the data plate. Then look at the base of the tank for rust and water stains. Rust plus age means replace. Clean and young means repair. See how long water heaters last and water heater replacement cost if you're on the fence.

Repair by heater type

Gas water heaters

Gas tanks fail at the pilot, the thermocouple, the gas control valve or the burner. A.O. Smith says a faulty gas control valve needs a professional, while blocked air screens and a dirty burner can be cleaned. Full detail on gas water heater repair.

Electric water heaters

Electric tanks fail at the breaker, the high-limit reset, the elements and the thermostats. A.O. Smith calls a tripped breaker a very common reason an electric heater stops heating. Elements and thermostats are some of the cheapest repairs on any heater. See electric water heater repair.

Tankless water heaters

Tankless units show an error code when something goes wrong, which makes them easier to diagnose. Scale buildup is the big one in hard-water areas, and A.O. Smith recommends descaling once a year. See tankless water heater repair.

RV water heaters

RV units are smaller and use different parts, often gas and electric together. Suburban warns that running the electric element with no water in the tank damages it. See RV water heater not working.

Is no hot water an emergency?

Usually not. A cold shower is miserable, but it isn't dangerous, and it's worth waiting for a normal appointment rather than paying after-hours rates. It is an emergency when:

• you smell gas
• water is pouring from the tank or flooding the floor
• the relief valve is blowing hot water or steam
• the heater is sparking, smoking or scorching

For a leak, shut off the cold supply to the heater and turn off the gas or the breaker before you call. Our no hot water page has the checks to run first.

Who to call for water heater repair

A licensed plumber handles nearly every water heater repair, gas or electric. Call the gas utility first if you smell gas. Call an electrician only if the heater is fine and the problem is the circuit feeding it. Tankless units are best serviced by a plumber trained on that brand, since parts and diagnostic codes vary.

When you call, have the brand, model and serial number from the data plate, the heater's age and the symptom. A plumber who knows the model can often bring the right part on the first visit, which saves a second trip charge.

Service and maintenance

A lot of repairs are avoidable. A.O. Smith suggests draining a few gallons from the tank every year to clear sediment, inspecting the anode rod yearly and having a professional look at the heater every couple of years. HomeGuide prices a tank flush at $75 to $250 and a general tune-up at $100 to $500.

Hot water in the toilet tank

If the toilet tank is filling with warm water, the water heater isn't the problem. Hot water is crossing into the cold line somewhere. The usual culprits are a failed cartridge in a single-handle faucet or shower valve, or a crossover valve from a recirculation system. Shut off hot water at the heater and see if the toilet runs cold again. If it does, hunt for the fixture that's crossing over.