Hi grandpajoe, smurfchops asked about water meters at the end of last month
http://www.theanswerb.../Question1100872.html
You might find some of the answers useful.
With my own experience and others I've come to the conclusion that the water companies just charge whatever they like.
I live on my own and am more than frugal with water but they still wanted £30 a month from me.
I phoned them up and told them I am unwilling to pay more than£20 a month and they actually said,'ok' so this is what I now pay.