The U.S. Environmental Protection Agency’s (EPA) Water Infrastructure Resiliency and Finance Center, in collaboration with the...
Reseachers evaluated detergent use in both dishwashers and washing machines
Consumers can cut back on dish and laundry detergent use by 50% or more and lower washing machine temperatures from hot to cold by using softened water, two recently released independent studies show.
The detergent savings studies conducted by the independent testing firm Scientific Services S/D Inc. of New York and funded by the Water Quality Research Foundation (WQRF) reveal that using softened water in washing machines can reduce detergent use by 50% and save energy by washing in 60°F cold water instead of 100°F hot water, achieving the same or better stain removal and whiter clothes compared to results in hard water. Using softened water in dishwashers can cut detergent use by more than 50% and get the same results.
Researchers used varying levels of hardness and several different brands of detergent in washing machines and dishwashers. They found significant savings for all levels of hardness, even hardness as low as 5 grains per gal.
The laundry study looked at stain removal, putting into the machines from half to the entire amount of manufacturers’ recommended levels. Water hardness ranged from zero to 30 grains per gal, and wash temperature was 60°F, 80°F or 100°F. Researchers found that using softer water is better at removing stains than increasing water temperature or using more detergent.
Notably, softened water with the least amount of detergent and lowest temperature provided a higher degree of whiteness compared to increased hardness and both high temperature and large amounts of detergent. This was found to be true for all stains and all the detergents tested.
The dishwasher study included tests that removed difficult soils and evaluated spotting and filming. Researchers found that softened water using almost 30% less detergent cleans as well as water at 10 grains per gal hardness level. That detergent savings rises to nearly 70% when comparing softened water with water at a 25-grain-per-gal level.
In dishwashers, the relationship between detergent and hardness was investigated with two consecutive wash-dry cycles for spot and film. One detergent was evaluated for five cycles to ensure that effects do not change with increased number of cycles.
The study also evaluated air-drying as a way to save electrical energy, which provided better results when using softened water.