According to our group water scheme the Dept of Environment has a regulation that stipulates that 150 cubic metres is free to every domestic supply. Our excess charge is 60c per cubic metre. This is our first year metered and have not had a bill yet. I just read the meter and it is showing 116 cubic metres (I hope, there are 3 black digits and then a red one so I am hoping it is similar to esb where you ignore the final digit, else in for a major shock!). The meter was installed about a year ago.
We are a house of 2 adults 2 kids and would be normal enough users of water - apart from being in the west we rarely have to water the garden and being lazy rarely wash the cars!
That TAP TIPs site is very good, thanks for the link ajapale.