I have sediment built up in my hot water tank. I'm trying to flush it, based on instructions I've found on the internet. I've turned off the tank completely, attached a hose to the faucet drain and shut off the cold water input line. I've also turned on the hot water in the kitchen sink and bathroom.

But...every time I shut off of the cold water line, within a few seconds, the water stops flowing (both to the kitchen/bathroom and to the drain). By turning the cold water on and off, I was able to get a fair bit of sediment out, but I don't understand why I can't get all of the water out of the tank?

Can anyone tell me what I'm missing here?

  • 2
    It sounds like the drain valve is getting plugged up... Commented Oct 17, 2016 at 3:35
  • @ThreePhaseEel - Thanks for the comment but what I don't understand is why would the drain valve get unplugged when I turn on the cold water going into the tank?
    – Rob P.
    Commented Oct 17, 2016 at 12:33

1 Answer 1


Open a hot water tap to relieve pressure and plug the drain valve into your garden hose. Turn on the hose for a second (no longer; you don't want to push sediment into the fixtures) to loosen up the sediment.

  • Depending on the amount of sediment, it might clog again. Better off using a length of wire if the drain will accommodate a piece of solid wire.
    – Mister Tea
    Commented Oct 17, 2016 at 12:29

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