The federal government has proposed legislation requiring dishwasher detergents to contain no more than trace amounts of phosphorus. Meanwhile, 16 states have enacted laws cutting phosphorus content to 0.5 percent, from 8.7 percent, as of July 2010. Anticipating that more states may follow, major manufacturers have already reformulated their products for all 50 states.
Earlier efforts by individual states to reduce phosphates or eliminate them entirely prompted some residents to cross state lines and smuggle higher-phosphate detergents into their homes, but it appears that such subterfuges will no longer be necessary.
For our latest tests, we bought 24 low-phosphate dishwasher detergents, including tablets, pacs, liquids, gels, and powders. And this time the news is better: Although none quite equaled the excellent (but now discontinued) higher-phosphate detergent that topped our Ratings in 2009, seven proved very good.
In our tough tests, we smeared dishware with a mix of 17 sticky foods such as chocolate pudding, peanut butter, rice, and macaroni and cheese, while pots received just the macaroni-and-cheese blend. We baked on the goo and assessed how well each detergent removed the soil, kept it from being redeposited, and avoided leaving water spots.
A key lesson that our latest tests reaffirmed was not to shop strictly by brand name, as different products from the same brand wound up near the top and bottom of the Ratings. The four Finish detergents we tested, for example, ran the gamut from the very best to the very worst in our Ratings. The six Cascade detergents also varied widely in performance. Our Ratings (available to subscribers) provide the specifics.
Dishwashing dos and don'ts
Any detergent cleans better if you scrape off heavy soil from dishes and pots before you load them. But you'll save energy and water if you don't prerinse them.
Load large items along the sides and back so they don't block the water and detergent. Face the dirtier side of dishes toward the center of the machine, and don't let dishes or utensils nest. Place items with baked-on food in the bottom rack, face-down toward the sprayer. Rest glasses upside down on prongs so they don't fill with water. Use the top rack for plastic and delicate items that are dishwasher-safe.
Dishwasher detergents and the hot water found in a dishwasher can be rough on silver, fine glassware, brass, bronze, cast iron, disposable plastics, gold-colored flatware, gold-leaf china, hollow-handle knives, pewter, tin, anything made of wood or with a wood handle, and possibly other kitchen ware. Hand-wash items that have value to you.
If glasses emerge from your dishwasher cloudy or spotted, or if a whitish crust collects on your dishwasher's heating element, hard water may be the culprit. Hard water also hurts cleaning performance. Contact your water company to determine the hardness of your water. If you don't have municipal water, use a home test kit ($10 to $25 at home centers and hardware stores). Consider installing a water softener if your water has a total level of calcium, magnesium, and other minerals at 7 grams per gallon or 121 milligrams per liter.
To prevent spotting and to help dishes dry better, most dishwasher and detergent makers recommend adding a rinse aid. Refer to your owner's manual for details. Some detergents and dishwashers recommend adding more detergent. If your water is hard, look for the instructions on your dishwasher detergent package or in your dishwasher's manual.
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