by Pauli Undesser, CWS-VI
The Water Quality Research Foundation (WQRF) released two new reports in February that, in combination with WQRF’s 2009 Study on Benefits of Removal of Water Hardness (Calcium and Magnesium Ions) From a Water Supply (also known as the Battelle Study) are encompassed in a body of research called the Softened Water Benefits Study. The two new reports are: Evaluation of Relative Effects of Hardness, Detergent Dose and Temperature to Evaluate Stain Removal Efficacy and/or Use of Less Laundry Detergent at Lower Water Temperatures (the Laundry Study) and Evaluation of the Effect of Water Hardness on Performance of Automatic Dishwasher Detergents and Savings Possible by Softening Water (the Dishwasher Study).
How typical! Just when the debate regarding the advantages and disadvantages of water softeners appeared to be simmering down, a new report comes along to shake things up again. This happens often in the scientific world because researchers evaluate high-profile topics to the nth degree. Any subject that is investigated from infinite points of view will provide observations that can seem to contradict each other or disturb general perceptions. To reach the pinnacle of understanding, it takes a significant amount of research to connect seemingly disconnected information and to provide clarity to the overall topic. Water has been researched in infinite ways, but new water-related research still has the power to surprise us. Various researchers are trying their hardest to achieve the ultimate level of detail for high-profile topics, which means that we need to continuously evaluate new data and reassess general perceptions.
Traditional cation exchange water softeners have only been around for about 110 years (it seems like forever), and have been heavily researched to assess their breadth of contaminant reduction capabilities. Water softeners have not been thoroughly investigated from infinite points of view, and the data that we do have does not even come close to reaching a pinnacle of understanding that helps assess the full impact these devices can have. More research will occur over time and seeing new reports may not come as such a surprise, but each of the findings might be worth reviewing. The latest reports confirm information that stress the utility of water softeners, tweak general perceptions and spur suggestions for further investigations. General explanations about the report findings are discussed in this article.
The tangible results
Both the Laundry Study and Dishwasher Study compare results of washing with water ranging from softened (zero gpg) to very hard (30 gpg) using various temperatures and detergent doses. It is generally known that softening water increases the efficacy of soaps and detergents. These studies quantify the increase in efficacy through reduction in detergent dose and go further to investigate the reduction of temperature and, in turn, energy savings. The Laundry Study investigated stain removal where detergent usage was 50, 75 and 100 percent of the manufacturers recommended level; water hardness ranged from 0 to 513 ppm (30 gpg) and wash temperature was 60, 80 and 100°F (15.5, 26.6 and 37.7°C). Nine different popular phosphate-free detergents were tested on nine different standardized stains. Statistical analysis was conducted to compare the ability of softened water to mitigate adverse effects of lower detergent dosage and lower wash temperature, in turn decreasing costs and energy usage. The most significant conclusion of the Laundry Study is the fact that stain removal is increased more by softening water than by increasing detergent dose or by increasing temperature. Decreasing hardness demonstrated to be up to 100 times more effective at stain removal (depending on the stain) than increasing detergent dose or temperature. Figure 1 and Table 1 display a comparison of Case 1: very hard water/high-detergent dose/high temperature versus Case 2: medium-hard water/medium-detergent dose/medium temperature versus 3: softened water/low-detergent dose/low temperature.
The fact that softened water combined with the least amount of detergent and lowest temperature provides the highest degree of whiteness compared to increased hardness with the highest level of detergent and temperature is a noteworthy finding. The main conclusion of this study is that when hard water is softened prior to its use in washing, detergent use can be reduced by 50 percent, and washing can be carried out in 60ºF (15.5ºC) cold water instead of 100ºF (37.7 ºC) hot water, and yet still achieve the same or better stain removal and yield whiter clothes. This was found to be true for all stains and all detergents tested. The significance of this finding impacts waste-stream remediation and energy consumption, though the full implications have not been quantified. These calculations are included in discussions regarding future endeavors that will spin off of this research.
Detergent savings was also evaluated for dishwashers. The Dishwasher Study included tests for removing difficult soiling in addition to spot and film evaluation. The relationship between detergent dose and hardness was investigated with three name-brand, non-phosphate automatic dishwashing detergents 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 an increased number of cycles.
Statistically significant improvements made by softening water with hardness were observed in spotting and filming performance, as well as in better soiling removal in automatic dishwashing. Detergent savings up to 70 percent was observed for dishwashing when softened water was used compared to hard water. Depending on the soiling, hardness reduction was found to be up to 12 times more effective at removal than increasing detergent dose. Hardness reduction was approximately six times more effective at reducing spotting, and twice as effective at reducing filming as increasing detergent usage (see Figure 2).
The Dishwasher Study also briefly evaluated persistence of the hardness-dose relationship, air-drying benefits and tablet detergents. A detergent that was run for an additional three cycles did show that the hardness-dose performance relationship persists. Air drying as a way to save electrical energy for dishwashing is promising and may give better results when softened water is used rather than hard water. Further experiments are required to fully substantiate this claim. Lastly, the results using liquid detergents were confirmed with tablet detergents. The beneficial effect of softening wash water was notably greater than the beneficial effects generated by the use of two tablets rather than one.
The Softened Water Benefits Study has provided new research to ponder regarding the benefits of water softeners. First, the Battelle Study evaluated energy savings from water upon maintaining the efficiency of appliances as well as limiting impacts on fixtures. It was demonstrated that for gas storage tank water heaters, up to 24-percent efficiency can be lost with hard-water usage. Moreover, the Detergent Savings Study investigated detergent reduction and further energy savings through decreasing wash temperature in laundry operations, and the possibility of using air drying in dishwashing.
Overall, it is still unclear whether these benefits outweigh the negative impacts of softeners, such as chloride introduction in the waste stream and extraneous water usage for regeneration. It is also not clear how alternative devices may fit into this research. We are far from reaching complete understanding on this topic, but the research will continue and someday will hopefully resolve the debate of softener advantages versus disadvantages.
To get more detailed information about the Battelle Study, the Laundry Study, and the Dishwasher Study, you can access the executive summaries, full reports and other resources by visiting the Water Quality Association (WQA) website at www.wqa.org. Note that some information may be restricted to WQA members only. The website also offers valuable information about water contaminants and how they can be addressed, and listings of manufacturers of certified water treatment products. You can also learn how to support research projects through WQRF, become a member of WQA, and find contact information for local water professionals who are members of WQA.
About the author
Pauli Undesser, CWS-VI is WQA’s Director of Regulatory and Technical Affairs and Toxicology Manager for WQA’s Gold Seal Certification Program. Previously, she was Product Certification Supervisor. Undesser holds an MS degree in biochemistry from Northern Illinois University and a BS Degree in chemistry from the University of Illinois-Urbana/Champaign.
About the organization
WQA leads the industry in customer service and turnaround time, and has been issuing the Gold Seal Mark to products since 1959. WQA is available to meet regulatory, consumer and marketing needs. If you are seeking product certification by a reputable ANSI- and SCC-accredited certification agency that can provide you with answers to certification questions, personnel ready and willing to assist throughout the entire process, as well as an agency that remains consistent with respect to certification decisions, contact WQA at [email protected] or (630) 505-0160.