Most loads in your washing machine are effectively cleaned with cold water. The only time you really need to use hot water (with bleach) is for virus- and germ-killing sanitation. Modern detergents are formulated to work in warm or cold water; heating water for laundry can bulk up your utility bill. Always measure detergent carefully – most people use up to twice as much as needed. It’s a waste of money, hard on your machine, and may actually make clothes look grimy.
From:: Home laundry money-savers.