Most loads in your washing machine can be effectively cleaned with cold water. The only time you really need to use hot water (with bleach) is for germ-killing sanitation on diapers or sickroom linens. Today’s detergents are formulated to work in warm or cold water, and heating water for laundry can chew into your utility bill. Be sure to carefully measure detergent – most people use up to twice as much as needed.