it depends on your water owner/authority and size of property. I am Thames Water also and live in an extremely small one bed flat, no bath, just a shower cubicle used once a day, washing machine used 2 or 3 times a week, I am out most of the week at work, but my rate is over £300 a year, which I feel is expensive, I don't know if a meter would be cheaper, but I have not been offered the opportunity, maybe because it would be cheaper, and less money for Thames Water..