How often should a water heater be serviced? Once a year, for both tank and tankless water heaters. That’s what Rheem, one of the largest manufacturers, recommends as a pro maintenance visit, and on San Diego’s hard water it’s not a step to skip. In between, a two-minute look every month or so catches most problems early. The one big exception is an old tank close to wearing out, which is often better left alone.

Why Hard Water Makes the Yearly Visit Matter Here

In 2025, each of the City of San Diego’s three treatment plants delivered water averaging close to 14 grains of hardness per gallon. Helix Water District, which serves La Mesa and El Cajon, averaged about 12 grains from its main plant. Both are hard. Heating that water drives calcium and magnesium out as scale. In a tank it piles up on the bottom, where the burner has to heat through it and you start to hear rumbling and popping. Inside a tankless water heater, scale lines the narrow water passages, so a descaling flush every year is standard practice on San Diego water. Many of our tankless customers book that flush with us every year.

What a Yearly Water Heater Service Should Include

Rheem publishes a checklist of what to ask a plumber for on an annual visit. It differs a little between tank and tankless heaters:

The anode rod is the one most people have never heard of. It’s a metal rod hanging inside the tank that corrodes on purpose, so the steel tank doesn’t. Once it’s eaten away, the tank starts to rust from the inside. Replacing a worn rod is a small job that can buy a tank years. After an anode rod replacement, a customer wrote that our technician had been candid about which services made sense right then and which could wait. That’s how a service visit should go.

Quick Checks Between Visits

None of these need tools. Do them every month or two, and call if anything looks off:

• Look at the base. Rust, a damp ring or a puddle under a tank is never normal.
• Check the relief valve line. The pipe running down from the valve near the top should be dry. Dripping can mean the valve is worn or the house pressure is too high.
• Listen when it heats. Popping or rumbling from a tank means sediment.
• Look at the straps. California law requires a tank heater to be braced against earthquakes. Two metal straps should hold it to the wall.
• Notice the water. Rusty hot water, a rotten-egg smell or hot water running out sooner than it used to are all worth a call.

If you smell gas near a gas water heater, leave the house first and call SDG&E or 911 from outside.

When an Old Tank Shouldn’t Be Flushed

A tank that has never been flushed and is past ten years old often has a thick layer of sediment holding back small leaks, and a drain valve that hasn’t moved in a decade. Opening that valve and stirring everything up can start the leak you were trying to prevent. One of our technicians told a customer exactly that: skip the flush on an aging tank and plan the replacement instead. If yours is in that range, read about the repair-or-replace decision on our water heater repair page before paying for maintenance.

For a heater with plenty of life left, a yearly service is cheap insurance. To book one, call (858) 567-0544 during business hours, Monday to Friday 8 to 5, and tell us if it’s a tank or tankless unit and roughly how old it is. You can also write to us from the Contact Us page. Courtesy Plumbing dates to 2007 and still answers to its founder, Tony Misleh, a master plumber; our license is CSLB #910268.