Re the meter sketch, have a look at your water suppliers website, search for water meter. Up here you can ask to have a meter fitted, you can change your mind and go back to rateable value after a trial period (6 months I think)- the meter will stay installed, if the house changes ownership the new occupiers will be metered with no choice in the matter.
That was the situation here, when I decided to have one fitted. There was an online consumption calculator, which when I used it suggested it was well worth my having a meter - later, once the meter was fitted, I found I was saving much more than even the calculator had suggested. I now pay between 1/3 and 1/2 metered, compared to what it would be using the rateable value.