Water heater maintenance: schedule, lifespan and costs
Updated
Overview
The water heater is the appliance most people forget about until the shower goes cold. Most homes have a tank heater, gas or electric, that keeps a tank of water hot around the clock. A growing number have a tankless unit that heats water as it passes through. Both kinds need a little attention each year: a flush or descale to clear out minerals, a quick test of the pressure relief valve, and every few years a look at the anode rod that protects a tank from rust.
Lifespan
A water heater lasts 8 to 20 years. A tank heater is at the low end, about 8 to 12 years. A tankless unit lasts about 20 years, because it has no tank to rust through.
What shortens that life: hard water, which coats the inside of a tank with sediment and clogs a tankless heat exchanger with scale. Skipping the flush, which leaves that sediment to cook on the bottom. An anode rod that was used up years ago and left the steel tank to corrode on its own. And high water pressure, which stresses the tank and every valve on it.
What extends it: flushing or descaling on schedule, replacing the anode rod when it's worn, and softening hard water before it reaches the heater.
The signs a heater is near the end: rust-colored hot water, moisture or rust around the base, a leak from the tank itself rather than a fitting, and rumbling that comes back soon after a flush. Check the label on the tank for the manufacture date. If it's past the middle of its lifespan and showing those signs, start planning for a replacement.
Maintenance schedule
These are the jobs that keep a water heater going, in the order worth doing them.
| Task | How often |
|---|---|
| Test the water heater pressure relief valve | once a year |
| Flush the water heater | once a year |
| Descale the tankless water heater | once a year |
| Inspect the water heater anode rod | every 3 to 5 years |
Replacement cost
Replacing a water heater costs $1,200 to $5,000 installed. A tank heater is at the lower end of that range and a tankless unit at the upper end, because tankless units cost more to buy and often need a larger gas line or new venting.
The rule of thumb for repair versus replacement: if the repair would cost more than half of a new heater, and the unit is past the middle of its lifespan, replace it. A leaking tank is a replacement, full stop. A failed element, thermostat, valve or igniter on a younger heater is a repair.
Common problems
- No hot water at all: on a gas tank, the pilot has gone out or the thermocouple has failed. On an electric tank, a breaker has tripped or an element has burned out. On a tankless unit, check the display for an error code.
- Hot water runs out fast: sediment is taking up space in the tank. Flush the water heater and see if the problem clears.
- Rumbling or popping: water trapped under sediment is boiling. The same fix, a flush.
- Hot water smells like rotten eggs: bacteria reacting with a worn anode rod. Inspect the water heater anode rod and replace it.
- The relief valve drips: either the valve has worn out or the water pressure in the house is too high. Test the water heater pressure relief valve, and if it keeps dripping, have the house pressure checked.
- Water around the base: a leak from a fitting can be tightened, but a leak from the tank itself means the tank is done.
- A tankless unit that swings between hot and cold: scale inside the heat exchanger. Descale the tankless water heater.
FAQ
How long does a water heater last?
A tank heater lasts about 8 to 12 years, and a tankless unit about 20. Hard water and skipped maintenance pull those numbers down.
Should I repair or replace a leaking water heater?
If the leak comes from the tank itself, replace it. A tank can't be patched. If the leak is at a fitting, a valve or the relief valve, that's a repair.
Does a tankless water heater need maintenance?
Yes. It has no tank to flush, but scale builds up inside the heat exchanger, so it needs descaling once a year, or more often with hard water.
Can I do water heater maintenance myself?
Most of it. Flushing, descaling and testing the relief valve are jobs for a homeowner with a garden hose and a bucket. Checking the anode rod takes a large socket and some muscle, and some people leave it to a plumber.
What maintenance does a new water heater need in its first year?
Test the relief valve and flush the tank at the end of the first year, same as any other year. The anode rod is new and doesn't need checking yet.