I'm planning on moving our hot water heater from its current location in our mudroom down to the basement, to live in what will become sort of a mechanical closet in the to-be-finished basement. My plan is to attempt to remove the existing PEX plumbing going to the water heater as close as possible to the nearest branch, but if that turns out to be difficult I'd like to cap off the old PEX just inside the wall.

If I end up doing this, it will leave two 10-foot runs of 3/4" PEX going vertically up that wall to a dead end. These segments will see no real flow, and I expect they will stay at least partially full of stagnant water. Is this a bad idea?

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    Upon further review, I'm positive these lines don't branch anywhere in the wall above before they get to the water heater, so I'm going to just cut them off down in the basement, leaving no standing water. Thanks for the answers though! Nov 7, 2010 at 13:15

2 Answers 2


Well Mike, the dead end plumbing shouldn't be a stagnant water problem, however if these dead ends will hold water when the rest of the system is drained, you might consider shortening them or installing a bleeder type cap. This would be helpful if you ever needed to drain the system completely or winterize the system for an extended vacation in Florida during those cold winter months.

  • An extended vacation in Florida sounds nice right about now! Just woke up to our first real frost of the year. Nov 7, 2010 at 13:14

It shouldn't be a problem.

The pipes will be sealed so there'll be no air getting in, so the water won't actually go stagnant (in the sense of "bad/smelly").

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