You can save on soaps and detergents with soft water and get clothes and dishes cleaner than when you use higher temperatures and more soap and detergent in hard water.
Two independent studies done by the Scientific Services Laboratories of Middletown, NY have verified that clothes and dishes come out of their respective washing machines cleaner when washed in soft water.
The Laundry study used waters of various hardness levels, with 50%, 75%, and 100% of the manufacturers recommended application of soaps and detergents, and varied the water temperature from 60 degrees, 80 degrees, and 100 degrees. Stains were used to measure the effectiveness of the cleaning. The stains used were blood, coffee, dust sebum (ring around the collar), grass, red wine, chocolate pudding, chocolate ice cream, barbecue sauce and ground in clay. The results showed that softened water had more effect than the amount of detergent or the temperature of the water.
The Dishwasher Study used waters of various hardness levels, with 30g, 55g, and 85g (g represents grams) of detergent. Items washed were dinner plates, silverware, and glasses. Standard soils used for filming and spotting included oatmeal, dry milk, and grease. Hard-to-remove-soils used were egg yolk, pizza sauce, spinach, brownie mix, fish, bread crumbs, and olive oil. The results showed significant improvements by softening hard water were observed in spotting and filming performance as well as in better soil removal in automatic dishwashing. Detergent savings of up to 70% was found when using soft water over hard water. Hardness reduction was found to be up to 12 times more effective at soil removal than increasing detergent dose.