Dishwasher detergents

Dishwasher detergent buying guide

Last updated: August 2013

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Ever since phosphates were eliminated from dishwasher detergents in the summer of 2010, consumers have been complaining about "clean" dishware coming out of the dishwasher covered in a white film or metal that's been discolored. Because phosphates foul waterways, they were banned in many states. Major manufacturers responded by reformulating their products for all 50 states eliminating all but trace amounts from dishwasher detergents. (Laundry detergents were already phosphate-free.)

Phosphates help to control water hardness, according to the American Cleaning Institute. They also boost a soap's ability to clean and prevent food particles from sticking to the dishes. Without it, dishes can emerge from the dishwasher with bits of food still attached, glassware filmed in white and aluminum that's tarnished.

The chorus of complaints we heard from readers after the switch caused Consumer Reports to recalibrate its dishwasher detergent tests. In the new tough test we take a set of clean glass dishware and uncoated aluminum sheets and wash them 20 times, simulating more than a month of machine washing, using the same detergent and with water that's harder than most. Our revised tests of tablets, pacs, liquids, gels, and powders changed the rankings of some products.

We also test the cleaning ability of the detergents by smearing dishware with a "monster mash" of 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 food, kept it from being redeposited, and avoided leaving water spots. A key lesson from out tests was not to shop strictly by brand, as different products from the same brand wound up near the top and bottom of the Ratings.

The best detergents cleaned well without leaving film on the glassware or discoloring the aluminum. This matters most in areas with hard water, which is more than half of the country. If your home has soft water, you can consider detergents that scored well for cleaning and pay less attention to the hard-water test results.

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.

Hard-water problems

Hard water hurts cleaning performance. If you're having problems getting your dishes clean, 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 of 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 detergent and dishwasher makers recommend adding more detergent. If your water is hard, look for the instructions on your dishwasher detergent package or in your dishwasher's manual.


Dishwasher detergents come in several forms, none of which showed a clear superiority in our performance tests. Although tablets and pacs tended to score high and gels low in our latest tests, it's too soon to say whether that trend will continue.


These deliver a conveniently premeasured amount of detergent in a solid cake.


These also deliver a conveniently premeasured amount of detergent, but in packets that dissolve in the water.


You have to measure out the proper amount for each load from a bottle.


Gel detergent is like liquid, but thicker.


It comes in a box. As with liquid and gel, you have to measure out the proper amount for each load.


The most convenient detergent we tested comes in a canister that works something like a revolver, automatically dispensing 12 doses from a cartridge. It performed well, but it's relatively expensive. And it takes up about as much space as a large-diameter glass in the dishwasher.


Besides ever-diminishing amounts of phosphates, dishwasher detergents may contain other additives, which may or may not be listed on the packaging.


Products containing bleach were not notably better at removing baked-on soils, although they may be more effective on tea or similar stains.


Enzymes help break up food for easier removal.

Rinse aids

These help prevent spotting, especially with hard water.


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