Customers must shoulder higher water and sewer rates to keep Hi-Desert Water District solvent, a consultant hired by the water district said last week. Steve Gagnon with the consulting firm Raftelis gave a workshop on the proposed rate hikes Aug. 7. “I believe what everyone wants to know is, ‘What’s going to happen to my bill,’” Gagnon said.  If they pass, the increases will cost a total of $10.81 per month extra in the first year for the average single-family home, Gagnon said. Residential customers’ water bills will go up an average of just over $4 this year and 8% more each year after that through 2029. Wastewater costs for those customers will rise about 14% for the first two years and 9.75% every year after that.