We were away from our regular home this past winter, and as a security measure we turned the water supply (within the house) off just ahead of the municipality's water meter. Before returning home a monthly bill was issued for 17000 gallons of water, but our valve ahead of the meter was turned off. How can this be possible? Are there things that cause water meters to mis register?

Do they read your meter every month, or check it ever few and estimate between them? Perhaps that usuage was actually for the previous months usage(as in the month PRIOR to the billing month)

Air will read the same as water.

If the valve ahead of the meter was shut then it's on them and you have a case. Good luck, Tom