Automatic Dishwashing Detergents:Important Source of Water-Polluting Phosphorus
When phosphates were banned in most laundry detergents in 1974 to clean up the Great Lakes
and other water bodies, an exception was made for automatic dishwashing detergents because dishwashers wouldn’t function properly without some phosphorus in the mix.
More than thirty years later, apparently this problem hasn’t been solved (though other detergents have been formulated to work very well without phosphates) so automatic dishwashing detergents continue to contain quite a lot of phosphorus.
We should be concerned about phosphates in detergents because phosphorus is the “limiting
nutrient” for most fresh water, including Canandaigua Lake. “Limiting nutrient” means that relative to the other basic nutrients needed for growth, in fresh water phosphorus is usually the most limited.
Adding a source of nitrogen or potassium to a water body will cause some response in plant growth; adding phosphorus gets a major response!
The usual measure of growth per unit of phosphorus added is 500:1, so that one pound of added
phosphorus will spur the growth of five hundred pounds of algae. This means that the one gram of phosphorus available in a tablespoon most dishwashing detergents will spur the growth of 1.1
pounds of algae, PER LOAD.
Here are locally available automatic dishwashing detergents and their ratings.
PRODUCT PERCENT Phosphorus AMOUNT of Phosphorus
Cascade Dawn Pacs 8 1.1 g / tspn
Electrasol Tabs 8.7 1.74 g / tblspn
Electrasol Powerball 8.7 1.8 g / tblspn
Electrasol Gel 8.7 2.2 g / tblspn
Cascade Liquid 4.5 1.0 g / tblspn
Casacade Complete 5.0 1.0 g / tblspn
Wegmans Gel 4.0 0.8 g / tblspn
Cascade Powder 6.9 1.1 g / tblspn
Cascade Powder Lemon 6.4 1.0 g / tblspn
*Wegmans Powder 5.3 0.6 g / tsblspn
*Palmolive Gel 3.3 0.6 g / tblspn
*Electrasol Powdr Advanced 4.5 0.72 g / tblspn
*Of the products currently available with phosphorus, we recommend:
Palmolive Gel
Wegman’s Powder
Electrasol Powder Advanced
and urge you to use them according to instructions. You may be able to find non-phosphorus automatic dishwashing detergents either in the “earth-friendly” section of your supermarket or through catalogue sales. Their efficiency is so dependent on the chemistry of your water source that we cannot make any claims for them.
You should check the capacity of the detergent holder built into your dishwasher. Most
of these detergents are rated to wash a load with a tablespoon of liquid or powder, but the
holder is often sized to suggest that 4-8 tablespoons are “normal.” Such a large amount of
detergent may, however, damage the washing machine. Four to eight tablespoons of most of these detergents will grow four to eight POUNDS of algae per load. The phosphorus content of your wastewater is little affected by a septic system, aerobic treatment system, or sewage treatment plant.
Source: http://www.canandaiguawatershed.org/files/October_Page_08.pdf
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