I have a free-standing bath in my bedroom and a separate shower stall in an adjacent room.

When we run hot water in the bath the shower head starts running-- not just a drip... more like moderate rain. This doesn't happen with cold water running in the bath. To be clear, this is not a shower/bath combo with diverter but two different faucets in separate rooms. The plumbing for both rooms was completed at the same time (about 8 years ago).

I'd be grateful for any ideas on what would cause this problem and how it could be fixed.

2 Answers 2


It may be due to a so-called 'power-shower': a little pump next to your loft tank that boosts the hot water pressure or just a well or thank pump that boosts pressure while water is in use.

If so, just check the gaskets in the leaking (hot-water) tap: maybe those are worn and cannot withstand the increased pressure or, if you have single-command handle, replace the inner cartridge.

  • Thank you. We don't have a power-shower but will certainly check the gaskets/cartridge. Further information: The shower includes a hand-held shower with its own flow control and an overhead shower with a separate flow control. There is one temperature control for both shower heads. It is the hand-held shower that runs when the bath tap is turned on.
    – sinjawns
    Commented Apr 18, 2018 at 15:06
  • 1
    In this case, the issue is most probably in the flow-control of hand-held unit.
    – DDS
    Commented Apr 18, 2018 at 15:22
  • Thank you-- this was the problem. I replaced the valve on the flow-control of the hand-held unit and it was fixed. I still don't understand why a failure there caused a problem from another room, but it did. Thanks for your help.
    – sinjawns
    Commented Sep 6, 2018 at 15:11

I have seen a similar problem where when the water pressure is low washerless faucets may sometimes run, the water pressure actually helps create the seal and when it is low the weight of the handle can turn the water on. I guess I did not provide a solution but usually a new O-ring and spring kit will tighten things up if not you will need heavier springs.

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