I live in St Louis, MO, where in many parts of the area the water system is old enough that they don't even have meters. The water division charges a flat rate

I live in St Louis, MO, where in many parts of the area the water system is old enough that they don't even have meters. The water division charges a flat rate based on the number of rooms and toilets/showers in the house, as that information is on file with the property tax assessor's records. If you ever add or remove a room or water fixture, you have to get a permit, which would get those upgrades reflected on the assessor's records.