After teeing the cold water line under my sink and connecting a hose, I shut off the cold water.

  • When I turn the sink on the coldest water setting, no water comes through the hose.
  • And when I turn the sink on the hottest water setting, no water comes through the hose either.

All is working correctly at this point!

  • But when I turn the sink on to the middle water setting (between hot and cold), warm water begins to come through the hose that was teed on the cold water side (even though I turned off the cold water).

Any idea how this could be happening?

When I turn off both the hot and cold water, no water comes through the hose.

My guess is that when the hot water line is on only, and the middle setting (between hot and cold) on the sink is on, this exposes the inactive cold water line, and the pressure pushes the hot water down the cold water line and out the hose. Is this correct?

1 Answer 1


You didn't say, but I'm betting this is a single-handle faucet. If it is, you're getting exactly the expected behavior. On any setting other than full hot or full cold, the faucet valve opens both water lines, and the water goes out wherever there's a hole. Since one of those holes is your cold water line, that's where it goes.

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