Annual
Water heater flush
Every gallon of municipal water carries tiny minerals. Over a year they settle at the bottom of your tank as a crusty layer that insulates the burner from the water it's trying to heat — so the burner runs longer, your bill goes up, and the layer eventually cracks the tank from the inside.
An annual flush takes about 20 minutes and adds years to the tank's life. East Bay water is moderately hard; annual is the right cadence.
What you’ll need
- Garden hose (long enough to reach a drain or outside)
- A bucket to catch the first gallon for inspection
- A flathead screwdriver (some drain valves have a slot, not a handle)
The basics
- Turn the heater to Pilot (gas) or off at the breaker (electric).
- Shut off the cold water supply at the top. Attach the hose to the drain valve at the bottom and run it to a drain or outside.
- Open the drain valve and a hot water tap upstairs to break the vacuum. Let it run until the water at the hose end runs clear — usually 10–15 min.
- Close the drain valve, remove the hose, turn the cold supply back on, wait for the upstairs tap to run at full pressure, then re-light the burner.
Watch out for
- The drain valve drips after you close it — it’s a $15 part to replace now, or a $250 service call if you wait.
- Loud popping or rumbling AFTER a flush — sediment is fused to the tank; may need an anode rod replacement or a new tank.
- Brown or rust-colored water at the outlet — the anode rod is spent; replace it before the tank wall goes.
Spot something off? Let Odosan diagnose it.
Photo of the water heater nameplate (top sticker). Odosan can read the brand, model, and install year and tell you exactly which anode rod fits.