High energy bills can become costly with old mechanical systems. Old pipes and appliances like water heaters are major causes. This is because the old pipes leak and lose energy. Investing in new water heaters and other plumbing improvements can reduce your utility bills. Some of the residential plumbing improvements to reduce high energy bills are: Replace the Water Heater Older water heaters can be extremely inefficient. Therefore, it may be one of the first plumbing improvements you want to invest in.