I have an electric shower in my bathroom, and the past few days it has
made a "whooshing" noise every few hours as if it's being turned on, and
a small amount of water comes out. This lasts about 20 seconds at a
time, then it stops. It otherwise works fine.

If I switch the shower off at the mains, it doesn't do it, so could I be
looking at a dodgy switch or similar making it switch itself on for a
short time?

Alex