(Editor’s note: Recently, WQA announced a new soap and detergent study is being undertaken that will investigate water hardnesses for three different representative detergent brands, varying water temperatures and nine stains in dishwashing. This article, on a similar study, originally appeared in the October 1970 issue of Water Conditioning Sales.)


By Florence Ehrenkranz, Ph.D., University of Minnesota
There are several quality requirements for water in the home. It must be safe, clean, non-staining, non-corrosive, and aesthetically appealing. For drinking and food preparation, we need water that is good tasting. For grooming, laundering, dishwashing and general cleaning, we need water that is soft.

Good use of water in the home requires an awareness by the consumer of what good water is. Good water use may require some changes in his values.

Specific points that have been important for a long time include a realization of the possibility of good flavor, as well as safety and clarity in drinking water. Some people think drinking water has to have “off” tastes or odors.

Also important is an understanding of home appliances and of what water temperatures and cleaning agents they require.

Some consumers think that all they have to do is turn the knob on a clothes washer to hot and that their wash water will automatically be hot without regard to the water supplied to the appliance. This is true in European washers that have a heater in them. A hot setting on a washer in this country is only true if hot water is being delivered to the washer from your water heater. A somewhat analogous conception may occur to for dishwashers.

Changes in values by consumers will be necessary, I think, if everyone is to have enough water of proper quality for all aspects of living. Consumers will need to accept that sufficient water of useful quality calls for more extensive treatment of water supplies and at higher cost, than we have paid in the past. They will have to learn that hard water and soft water do not have the same cleaning capabilities, nor do cold and warm water.

Water quality has an important effect on household electric dishwashers. The current standard for dishwashers, established by the American Association of Home Appliance Manufacturers, specifies that water should have a temperature of 150°, plus or minus 5°, a maximum total hardness of 10 grains per gallon and be supplied at a pressure of not less than 30 pounds. As for detergent, it specifies the kind and quantity recommended by the manufacturer.

A St. Paul manufacturer of household electric dishwasher detergents distributes a booklet on technical aspects of automatic dishwashing which is prepared by the Home Service Section of its Research and Development Division. It calls for water softer than the 10 grains specified by the American Association of Home Appliance Manufactures. It states that any water harder than eight grains is a problem and a troublemaker.

Other information on dishwashing in household electric dishwashers comes from research in the former Clothing and Housing Research Division of the US Department of Agriculture and some work in the Household Equipment Laboratories of the University of Minnesota.

The USD workers in a May 1966, article in the Journal of Home Economics evaluated the effects of five water temperatures, two water hardnesses, three dishwasher detergents and two detergent concentrations. The water temperatures were 100, 120, 140, 150 and 180°F. The harnesses were: soft water with approximately 17-ppm hardness minerals and hard water with 167-ppm hardness minerals. The detergent concentrations compared were 0.20 percent and 0.40 percent.

Selected combinations of the variables were investigated in a set of three experiments. In experiment I, half of the loads were washed in hard water and half in soft water. The water temperatures used with each of the three detergents were 120, 140 and 160°F. With each detergent and for each temperature, results with the soft water were superior to those with the hard water.

In experiment II the variables were hard and soft water, two detergents and two detergent concentrations. The single water temperature used was not reported. Again, soft water gave superior results to hard water. Results with the 0.40 percent detergent concentration did not differ significantly from those with the 0.20 percent concentration.

In experiment III, five water temperatures and two detergents were used with soft water. As water temperature increased. Overall soil removal increased.

The summary of the article includes the following statement: “Use of a dishwashing compound suited to local water conditions can improve the performance of a dishwasher. There was little justification even with hardened water for using more detergent than the amount recommended by the dishwasher manufacturers.”

A more limited study was done by a graduate student at the University of Minnesota. She used one detergent, two dishwashers, two water temperatures, 125 and 150°F; softened (0-1 grain) and naturally hard (15-19 grains) water. An artificial soil (margarine, dry milk and cocoa) was used. The summary of the report states that, “softened water gave better dishwashing results than hard water and some evidence that warm, softened water is as effective in removing soil as hot, hard water.”

The amount of phosphate required in dishwasher and clothes washer detergents is related to how hard or soft the water that is used. The report titled Phosphates in Detergents and the Eutrophication of America’s Waters, which was submitted to the 91st Congress, quotes the manufacturer of the dishwasher compound Electrasol as specifying 5.54 percent of phosphorus for soft water formulations and 8.93 percent of phosphorus for hard water formulations. If a concentration of 20 percent detergent is used, a dishwasher with a 2.5 gallon fill and two washes would use 37.8 grams of dishwasher detergent. This amount of detergent would contain 2.7 grams of phosphorus in soft water formulations and 3.37 grams in hard water formulations.

The government report just mentioned quotes McCutcheon’s 1969 Annual for the following information on heavy-duty detergents designed to do the family wash in a washer: “They invariably contain a surfactant plus ne or more ‘builders’ and, in addition, one or more ‘fillers’…”

Builders are chemicals that increase cleaning ability by neutralizing acid, partially softening hard water, dispersing and suspending dirt.

Except where substitutes such as NTA have been introduced, the builder in all-purpose laundry products is one or more phosphate compounds. Though the builder usually accounts for 50 percent or more of the product, the percentage of phosphorus as such is less.

Roughly half of the phosphorus polluting our waterways comes from domestic sewage, according to F. Alan Ferguson of the Stamford Research Institute. According to the US Canadian International Joint Commission, 70 percent of the phosphorus in US municipal sewage comes fro phosphate-based detergents.

We can launder without phosphate detergents. Commercial laundries and institutions have been doing it for years. They use soap and softened water. We can wash dishes without phosphate compounds. We can if we use softened water. Phosphate-free compounds are available for the purpose. Even ordinary salt soda does an excellent cleaning job.

National surveys have been carried out by manufacturers to find out how women do their laundering in the home. The kind of information I shall give was obtained by a university professor in surveys in Illinois. Based on 150 interviews, Dr. Betty Jane Johnston reports that the homemakers depended primarily on water, liquid detergents and bleach. Slightly more than half reported soaking some items.

Most women named additional products used I the washer. For the most part, they were products that served as builders by softening water or adding alkalinity. Little or no soap was reported used, probably because of its unavailability in a formulation suitable for clothes washing. A few homemakers still make and use lye soap. The survey revealed that women don’t always know whether the water they use is hard or soft.

The concluding remarks of the survey might be summarized as follows: The habits of the wringer-owner are formed. These habits won’t be changed. On the other hand, the owner of the automatic washer is ready to try new products for their ‘easy’ and ‘instant’ appeal. But she needs principles to guide her. She has to learn why certain types of procedures are recommended. So I note: We again return to a need for education or knowledge.

Enzymes are an example of a product with easy and instant appeal. According to an article by Elizabeth Shelton in The Washington Post, “The biological washday miracle is a $1.5 billion-a-year business. Some 500 million pounds of enzyme laundry aids are sold annually.” The quality of water is far more important to a clean wash than enzymes, yet it gets relatively little attention.

Another easy and instant appeal answer in laundering is the soil-release finish. A recent study used cotton and polyester fabrics and blends of polyester and cotton fabrics to explore the value of various laundering procedures. The different fabric samples were soiled artificially and laundered in a Terg-O-Tometer “under optimum conditions.” The investigation was a careful one. One conclusion reached was that “the soil release finish became less effective with repeated soiling and laundering.” The investigator suggests the permanency of the soil release finish needs improvement. As for the homemaker, then, a soil release finish is not the easy answer in home laundering. What is important is water of good quality, properly used.

I did a little study about 10 years ago in which towels and sheets were use din home management houses, washed twice weekly or weekly in the Household Equipment Laboratories, and examined visually by three home economists. 138° softened water of zero to two grains hardness was used throughout the study. The results obtained with all-purpose products were judged superior to those obtained with a mild soap product. The homemaker, therefore, even with softened water, cannot us a mild soap successfully at this water temperature. A built laundry soap makes all the difference.

In an earlier study I soiled swatches with radioactive dirt, Carbon-14, so we could follow it the way we follow things through the bloodstream. A built laundry soap versus an all-purpose detergent were compared. The detergent was used with hard (24-25 grains) water and with softened water. The soap was used with the softened water only. The built soap, at a concentration of 0.2 percent in softened water, was superior to the detergent in either hard water or in softened water.

In summary, the available water supplies will be used best by consumers who are informed, who are willing to examine their values and habits, and where necessary, will change habits and priorities.

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