Hard water doesn't clean as well as soft water because much of the detergent added to the washer goes to soften the water instead of to clean the clothes. This means you must use more detergent than in soft water. Heavy-duty liquid detergents remove soil in hard water almost as well as powdered phosphate detergents and do not contribute to water pollution. Soap and powdered detergents without phosphates do not perform satisfactorily in hard water. To prevent problems, take two actions.
All detergents perform better at higher temperatures in any quality of water.
Second, soften the water. Water softener systems that exchange sodium for calcium and magnesium may also be connected to the water supply lines for the washer, kitchen or entire house. These softeners will increase the sodium content of the water, so persons on sodium-restricted diets should consult their physicians before adding them to lines that supply water for drinking and cooking. To remedy existing problems, fill the washer with the hottest water appropriate for the fabric. Add four times the normal amount of phosphate detergent or liquid laundry detergent and 1 cup of precipitating or nonprecipitating water conditioner.