Why this matters
Minerals and grit from the water supply fall to the bottom of the tank. Over a gas burner the crust acts like a blanket, so the flame works harder and the tank crackles. In an electric unit the heap can swallow the bottom element.
Before you start
- If the tank is rented, check your contract; some providers prefer to do maintenance themselves.
- Gather a length of hose, a pail and a pair of work gloves.
- Know that the water inside is hot enough to scald.
Our crew would go about it like this
- 1
Shut off the gas or breaker and the cold supply, then drain the tank.
- 2
Check anode, dip tube, thermocouple or elements depending on the fault.
- 3
Install the new part or unit, bleed the air and refill before firing.
- 4
Test the relief valve, draft at the vent hood and outlet temperature at a tap.
Step by step
- Turn the gas control to its pilot or vacation mark; for an electric model, kill its breaker.
- Shut the incoming cold valve above the heater.
- Thread a garden hose onto the bottom spigot and lead it over to the basement floor grate.
- Let air into the system through a hot faucet on an upper floor.
- Turn the spigot and keep it running till the stream comes out free of flakes.
- Shut the spigot, reopen the incoming cold and wait for the upstairs hot faucet to flow without sputtering.
- Restore gas or power.
| What you see | Meaning |
|---|---|
| Clear water quickly | Little sediment |
| Grit and flakes | Normal build-up |
| Rusty water throughout | Possible tank corrosion |
Handing it over to us
Call if the drain valve leaks, the tank still rumbles after flushing, or water appears at the base. See water heater repair and tank or tankless.
Markham note: village-core houses tend to hide cast iron and galvanized behind plaster, while Cornell and Box Grove builds run PEX to a manifold. We ask the year your house was built so the right fittings ride along on the truck.
Straight from the phone log
How often should I flush my tank?
Once or twice a year, more often with hard water.
Can I flush a tankless heater the same way?
No. Tankless units need descaling with a pump and solution.
Ready to get it fixed?
One call, a clear explanation, and work finished tidily before we leave.