When should you replace your water heater?

How long a water heater lasts

A. O. Smith puts the average life of a water heater at about 8 to 12 years, and says it varies with where and how the unit was installed, how it was maintained and the water quality. ENERGY STAR says that if you suspect your water heater is more than 10 years old, it is time to consider replacing it, before an emergency forces the choice. When a tank fails suddenly, you're likely to take whatever is in stock, which ENERGY STAR notes often means a less efficient model.

So the useful question is not just "is it broken?" but "how old is it?"

How to tell how old yours is

Find the label on the side of the tank. ENERGY STAR says you need the brand name and serial number: some labels print the manufacture date right next to the serial, and for the rest the date is coded into the serial number itself, in a pattern each maker uses. Our guide on finding a water heater's model and serial number shows where the label usually is and how to read it.

Signs it's failing

• Water around the base of the tankENERGY STAR notes water at any joint, seal or seam is a problem, since the system should be fully closed. A. O. Smith treats leaks around the base of the tank as a sign it's probably time to replace.
• Rust or corrosionVisible corrosion on the tank or around the water lines, or rusty water from hot taps, can mean the inside of the tank is corroding.
• Rumbling or poppingUsually sediment at the bottom. ENERGY STAR says any noises should be checked out. A flush may help a younger tank.
• Not enough hot waterSediment can shrink usable capacity, and parts like a heating element or thermostat can fail.
• Erratic operationA. O. Smith lists a heater that runs erratically, along with age over 10 years, as a reason to think about replacing.

Repair or replace?

Some problems are parts, and parts can be replaced. A. O. Smith names a failed thermostat and a failed heating element as common causes of trouble, both replaceable, and says a temperature and pressure relief valve that won't release water when tested should be replaced with a new valve. Leaks from a fitting or valve can often be fixed too.

A leak from the tank body is different: the tank is the part that's failed. Put that together with age. A young heater with a bad element is usually worth fixing. An old heater with a leaking tank, or one needing a second repair, usually isn't. A licensed plumber can tell you which you have.

What to replace it with

• Same type, tankThe simplest swap. Gas for gas or electric for electric, in a size that matches your household.
• Heat pump water heaterAn electric tank that uses a heat pump to move heat from the surrounding air into the water. ENERGY STAR recommends an ENERGY STAR certified heat pump model and estimates it can save a household of four more than $330 a year on electric bills compared with a standard electric heater.
• TanklessHeats water as you use it, so there's no tank to store or leak. It has its own upkeep: Rheem says to descale it at least once a year.

ENERGY STAR mentions rebates and a federal tax credit for eligible heat pump models. Rules change, so check what applies to you with your utility and a tax professional.

Installing the new one

A. O. Smith says its heaters are installed by local independent contractors. Replacing a water heater often requires a permit and an inspection, especially for gas, because venting, gas lines and relief valve piping all matter for safety. Ask your plumber to pull any permit your town requires. Keep the receipt, the warranty and the install date together.

Questions people ask