We recently rented our house out for a year and the tenants did
not get our permission to have a water meter installed.

Three Valley are refusing to give us unmetered water now.

I was under the impression (although it may well be erroneous) that if the
householder changes, they can insist on a water meter anyway. i.e. as you
are the new "tenant", they can install one even if there wasn't one already.
I am probably misremembering, though.

Christian.