You say sewage is charged with reference to water usage. What if the biggest aspect of water usage is for gardening? Will I then have to pay more for sewage than is used? Not all water that flows in flows out especially if grey water is also used for gardening. Then there are other aspects such as car washing or pressure washing decking as well as drinking and kitchen evaporation during cooking .Also usage for family pets , both drinking and cleaning of both pets and their facilities. I suspect very little of water consumption is actually fed into sewers. This seems to be a very flawed and badly thought out approach.