Folks

I've recently moved house and inherited a bit of a mess of dodgy DIY
stuff (and it's bad when I, the master of dodgy DIY, consider it
dodgy).

Having just plumbed and fitted an upstairs bathroom, with many thanks
for some good advice from the group, I've discovered the shower in the
downstairs bathroom is fed from the water tank.

I've always understood that an electric shower had to be fed from the
mains supply. The question is, is this just an annoyance to be sorted
when time permits or is it a danger which should be sorted as soon as
possible?

The flow rate is poor, understandably, but just about acceptable which
is probably due to the shower being on the ground floor and the tank
being in the attic above the first floor i.e. about a floor and a half
above.

Second question - should an electric shower be plumbed with 15mm or
22mm pipe?

thanks

tommy