Flushing a tank water heater removes sediment that settles on the bottom from Lake Michigan water. Turn off the gas or power, close the cold-water supply, attach a hose to the drain valve, open a hot faucet upstairs, and drain until the water runs clear. Then close the drain, refill with the hot faucet open, and restore heat. Once a year is a good habit on younger tanks. On a tank that has never been flushed in many years, be careful: the drain valve may clog or fail to reseal.
Why Chicago tanks collect sediment
Chicago's water comes from Lake Michigan and is treated by the City. It carries moderate mineral content. When water heats, some of those minerals drop out and settle. Over time, the layer insulates the burner from the water, wastes energy, and makes popping or rumbling noises.
What you need
- A garden hose long enough to reach a floor drain or outside.
- A bucket.
- Gloves.
- A flat screwdriver or wrench for the drain valve, depending on type.
Water heater acting up? Talk it through by phone.
Call 000 000 0000Steps for a gas tank
- Turn the gas control to pilot or off.
- Close the cold-water valve on top of the heater.
- Attach the hose to the drain valve and run it to the floor drain.
- Open a hot faucet somewhere in the house to let air in.
- Open the drain valve. Water will be hot; keep clear.
- Drain until clear. Briefly open the cold valve to stir sediment, then close it again.
- Close the drain valve, remove the hose.
- Open the cold valve, keep the hot faucet open until water runs steadily.
- Return the gas control to on.
Steps for an electric tank
Same as above, but switch off the breaker first, and do not restore power until the tank is completely full. A dry element burns out in seconds. See electric water heater repair in Chicago.
When not to flush
If a tank is many years old and has never been flushed, sediment may be packed hard. Opening the drain can clog it open or leave it dripping. In that case, a professional can decide whether to flush or simply plan for replacement. See water heater replacement in Chicago.
Tankless units
Tankless units are descaled, not flushed. Isolation valves let a pump circulate a descaling solution through the heat exchanger. See tankless water heater repair in Chicago.
Safety
Water from the tank is hot. Keep children and pets away. If you smell gas, stop and leave; call Peoples Gas from outside if you live in Chicago, or Nicor Gas in most suburbs.
Local note
A flush is a good chore for a mild fall weekend, after a walk on the Lakefront Trail and before the heating season puts heavy demand on the heater.
What to expect when you drain
The first gallons often come out cloudy or with white or tan flakes. That is normal sediment. If the water stays brown after many gallons, the tank may be rusting inside, which is a sign it is near the end of its life. If the drain valve clogs, close it, wait a minute, and try opening and closing it again; sometimes the flow clears the blockage. If it will not clear or will not reseal, leave it closed and get help, as forcing an old plastic valve can break it.
Replacing a plastic drain valve
Many tanks come with plastic drain valves. Replacing one with a full-port brass valve makes future flushes faster and more reliable. It requires draining the tank, so it pairs well with an annual flush.
Keep a log
Write the date of each flush on a tag hung from the cold pipe. It helps you and anyone servicing the heater later.
Testing the relief valve
While you are at the heater, lift the relief valve lever briefly to make sure it opens and reseals. If it keeps dripping afterward, it may need replacing. Make sure the discharge pipe points down toward the floor or drain.
Related guides
See anode rods and winter hot water problems.