Why flush
Settled grit forms a blanket between the flame and the water and causes rumbling. Flushing can improve efficiency.
Steps
- Switch the burner to off, or kill the breaker.
- Shut the cold inlet valve.
- Connect a hose at the bottom spigot, other end over the floor drain grate.
- Open any upstairs hot tap a little.
- Open the drain valve and let it run.
- Close, refill, restore power or gas.
Caution
Water is hot. Older drain valves may leak after opening.
If the tank is old and never flushed, consult a plumber first.
Help
See water heater repair.
Gas versus electric tanks
With gas units, set the control knob to pilot or off first. On an electric tank, turn off the breaker first; running the elements without water burns them out within seconds. When refilling, keep a hot tap open until water flows steadily without spitting air, then restore power or relight.
What comes out
Expect cloudy, gritty water at first. In hard-water areas, you may see white flakes or chips of scale. If the drain valve clogs with sediment, gently opening and closing the cold supply can push it through. If very little comes out, the sediment layer may be heavy and hardened.
Anode rods
The anode rod protects the tank from corrosion. An anode inspection every few years, with replacement once it has worn thin, can extend tank life.
When to put the tools down
Some of this is homeowner work and some is not. Stop and phone us if you see any of these:
- Showers going cold sooner than last winter
- Crackle and knock from sediment as it heats
- Brown tint on the hot side alone
- A puddle forming beneath the tank
- Anything involving the gas line, the venting or cutting into a wall
Quick answers
How often should I flush?
Many manufacturers suggest once a year; homes with harder water may benefit from more frequent flushing.