Yeah I know how much it is!
I wish I could point to something that's blatantly obvious, but I can't. I don't wash my car, I don't own a pool, a pond or any sort of water feature. We both have showers, although my 2 year old has a bath every night, it's not a big one.
We switched the stop tap off and the water meter doesn't move, so if it's a leak it's in the house, but with everything off I can't notice it moving either.
Faulty meter maybe? or incorrect billing calculation? that really doesn't sound right!