Water heater age and when to plan a replacement

A water heater can seem fine and then fail without warning. Once a tank is more than 10 years old, it's time to start planning its replacement. A sudden failure can mean cold water, and sometimes a ruptured tank and water across the floor. An emergency replacement is also often more expensive, and it usually limits you to the models the plumber has on hand.

How to find its age

The age is usually coded into the serial number on the rating plate, the label on the side of the tank. Sometimes the manufacture date is printed on the same label. If it isn't, look up the brand and serial number together on the maker's site or a water heater industry site, because each maker uses its own code.

If you have the inspection report from when you bought the house, it may list the water heater's age. Once you know the age, write it on the tank with a marker.

The signs it's wearing out

• Corrosion. Rust on the tank or around its water lines means it's breaking down.
• Leaks. Water from a joint, a seal or a seam usually means a problem, and a leak can get worse.
• Rust in the hot water. It usually means the inside of the tank is corroding.
• Less hot water. Sediment builds up inside an aging tank and reduces how much hot water it holds.
• Rumbling. A rumbling or vibrating tank is straining, very often because of sediment on the bottom. Have any new noise checked.

Water heating takes up to 20 percent of a household's energy, the second-largest share after heating and cooling. Sediment builds up with age and poor maintenance, and minerals in the water can corrode the inside of the tank.

An annotated example

What to do next

Write down the brand, model, serial number and age, and keep them with your home records. Write down any of the signs you see, and ask about them at the next service.