The best they can do is to approximate these costs by relying on impact studies and by partially accounting for the difference in costs depending on the uses, the location, and the time of the year. First, part of the water abstracted is returned to the environment. If the water that is returned is of the same quality, and if it is returned where it was pumped, then it is not abstracted water that should be charged but rather water that has been used (and not returned to the environment in the catchment).