01 December 2016

Soft Water Laundry Study and Savings

The Water Quality Association commissioned a series of experiments to determine how water hardness impacts clothing stain removal. Specifically, a series of experiments were conducted to “compare the effects of different detergent dose, water hardness, and wash temperatures on the stain removal performance of five household laundry detergents.”

Experiments were performed with the following variables:

• Detergent usage was 50, 75 and 100% of the manufacturers recommended level.

• Water hardness levels of 0 and 513 ppm (30 gpg) plus a center point level of 257 ppm (15 gpg) were employed in these experiments.

• Wash temperatures tested were 60, 80 and 100ºF.

Stain removal for the following nine stains were studied: blood, coffee, dust sebum, grass, red wine, chocolate pudding, chocolate ice cream, barbecue sauce, and ground in clay. In general, detergent use and the energy required to heat the water is very high for each of the stains tested. Six liquid and three powder detergents and standard soiled/stained cotton swatches were used in this study.

The results showed the following conclusions:

• Stain removal performance increases dramatically when hardness is removed - even when dose and temperature are also lowered. Depending on the stain, hardness reduction was up to 100 times more effective at stain removal than increasing temperature or increasing detergent dose.
• Even when 50% of the detergent is used at a lower temperature of 60ºF instead of 100ºF, the washing yielded improved results with softened water compared to when hard water was used.
• Softening water will allow the use of less detergent and save energy by lowering water temperatures while still maintaining or improving performance.
• When water of any hardness is softened prior to its use in washing, the detergent use can be reduced by 50% and the washing can be carried out in 60ºF cold water instead of 100ºF hot water and achieve the same or better stain removal yielding whiter clothes.

Source: https://www.wqa.org/Portals/0/WQRF/ResearchStudy_BenefitsOfSoftenedWater_ExecSummary.pdf