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How often to flush a water heater
Once a year. On this schedule a tank water heater is flushed in October, with its anode rod checked at the same time, and a tankless one is descaled in September.
3 jobs a year, timed for mild winters. Tick them off as you go.
September
October
"Add these to my calendar" opens the free planner with this already ticked. Tick the rest of your house there, and it saves one calendar file that repeats every year.
The numbers, worked
A tank water heater gets 2 jobs a year here, both in October: flush the sediment (or book it) and have the anode rod checked. Doing them together is one visit a year.
A tankless water heater gets 1 descaling a year, in September, or 2 in the hot and dry band (March and September). Pick your climate above to see it.
Questions
What if my water heater's manual says something different?
Follow the manual. The dates here are easy to move: change the reminder in your calendar to match.
Is the tankless schedule different?
Yes. A tankless heater has no tank to flush; it is descaled instead, once a year in September, and in the hot and dry band also in March.
Does this page say how to flush it?
No. It says when the job comes due. Each line says "or book it" because many people have a plumber do it.
Can I get a yearly reminder?
Yes. "Add these to my calendar" opens the free planner with Tank water heater ticked; switch it to Tankless there if that is what you have.