I replaced my water heater 2 years ago, this weekend I plan on flushing it. I have read steps anywhere from turn off the gas and stop the water line, to just open the spigot at the bottom and fill up a bucket a couple times. How effective is just the spigot method without turning off the water supply or shutting off the gas supply and burner? I have a 4 gallon bucket I plan to use and just as a test I opened the spigot and was surprised how powerful the water flow was.

Can I do any damage by just draining the water via the spigot? 4 gallons at a time and not a continuous run? Is it effective to do this or am I just wasting hot water?

  • Shut off the gas, and open a few hot water taps in the house. Let the water run until it's no longer hot, before you start draining the tank. – Tester101 Sep 19 '17 at 14:15
  • So its much more effective to have the tank off? – treeNinja Sep 19 '17 at 18:51
  • no point in trying to heat the water you're draining. Besides, messing around with 120°F+ water can be dangerous. – Tester101 Sep 19 '17 at 21:53
  • I usually turn the gas control to pilot then I don't have to relight. – Ed Beal Dec 6 '17 at 14:39

I hook up a hose to the lower valve ; the other hose end is outside. I put a ball cock / 90 degree shut-off valve on the hose. Open the heater valve then open and close the ball cock at roughly 30 second intervals , the intent is to stir up sediment. Several cycles. Leave the gas and the inlet valves open. The burner will come on and the heat will help move sediment. It does waste hot water but should significantly extend heater life depending on your water. The objective is to remove sediment ; you change water every time you open a faucet. If you are limited to only a bucket , don't bother. Assuming a typical US domestic water heater; the inlet and outlets are at the top , fortunately the inlet has a pipe going to the bottom of the tank . This inlet and the burner coming on will tend to stir the sediment. Don't turn on any faucets while flushing, as you could mess them up with sediment. You could put the outside end of the hose in a bucket, it will catch some of the sediment and indicate progress.

  • If you're going to leave the heater on, you should at least turn it down. 120°F water can easily scald you. – Tester101 Sep 19 '17 at 21:51
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    The burner will never recover temperature fast enough. As long as you do't burn yourself on the original inventory. 120 F won't burn on a short exposure. ( My heaters are only set at about 125F). – blacksmith37 Sep 20 '17 at 20:25
  • I do plan on running the hot water before draining. – treeNinja Sep 22 '17 at 15:37
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    It can damage some heaters to have them on while flushing, but I turn off the supply drain the tank and then turn the supply back on with the drain open (gas control to pilot). This really stirs the bottom better than any other method I have tried. – Ed Beal Dec 6 '17 at 14:43
  • You may want to make sure you are reasonably well-read on the latest about Legionella before staying at 125F. – Harper - Reinstate Monica May 24 '18 at 19:34

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