Some longtime users were furious.

“My dishes were dirtier than before they were washed,” one wrote last week in the review section of the Web site for the Cascade line of dishwasher detergents. “It was horrible, and I won’t buy it again.”

“This is the worst product ever made for use as a dishwashing detergent!” another consumer wrote.

Like every other major detergent for automatic dishwashers, Procter & Gamble’s Cascade line recently underwent a makeover. Responding to laws that went into effect in 17 states in July, the nation’s detergent makers reformulated their products to reduce what had been the crucial ingredient, phosphates, to just a trace.

While phosphates help prevent dishes from spotting in the wash cycle, they have long ended up in lakes and reservoirs, stimulating algae growth that deprives other plants and fish of oxygen.

Yet now, with the content reduced, many consumers are finding the new formulas as appealing as low-flow showers, underscoring the tradeoffs that people often face today in a more environmentally conscious marketplace. From hybrid cars to solar panels, environmentally friendly alternatives can cost more. They can be less convenient, like toting cloth sacks or canteens rather than plastic bags or bottled water. And they can prove less effective, like some of the new cleaning products.