Why does cold water come out of my hot water line?

Question posted on the Quora platform.

893 views.

“Why does cold water come out of my hot water line when I shut off the hot water?”

My Response:

I take it you’re speaking about the tub and shower valve? Anyways on a tub and shower valve.

A riser in the wall is going to feed the shower head, and this pipe has water many times on different plumbing fixtures.


Will carry or release the shower valve riser water that remained in the line. This will drain, and stop in a minute.

Now if you were talking about a line, that water would not stop. Let’s say, a faucet and the cold is on the right, and the hot is on the left.

If the water keeps running when you shut off the cold (right side).


The water is installed in reverse, so let’s say the hot is on the left, and the cold is on the right. Well, somewhere, it is cross-connected.

I Hope This Helps.

422 21st ST San Diego, CA 92102 

Call Now! FREE Estimate.