Appliances are not built to last forever, and eventually they need to be replaced. Think about your washing machine or dishwasher: They are some of the biggest users of water in the home and can become less efficient and technologically outdated the older they get. The rule of thumb is this: If either of these is more than 10 years old, consider getting them replaced. New appliances feature new technology that not only uses significantly less water, but also does a better job at cleaning your clothes and dishes. Just switching to a new model dishwasher can save you as much as 25 gallons of water per load.