Choosing a new toilet is a lot more complicated then it used to be. First, you have to choose between a gravity-flush and a pressure-assisted model. The latter generally use less water, but you might have to contend with a loud whoosh when you flush. Also, these toilets require water pressure of at least 25 pounds per square inch to work well.

While most of the 25 models tested for our latest report on toilets (story and ratings available to subscribers) use no more than the federally mandated 1.6 gallons of water per flush (gpf), more toilets use even less, including dual-flush models that have one flush mode for liquid waste and another for solid waste. (Read our Buzzword on greenflushing.)

Testers used blue dye to simulate liquid waste and a mix of 160 plastic balls, two latex cylinders, and seven sponges weighted with screws to mimic solid waste. Thirty-one gallons of blue dye and 1,125 flushes later, they found that not all models could flush with success. The 1.28-gpf Toto UltraMax II needed two flushes to clear all the dye. And some dual-flush toilets that tout their water-saving ability didn't do a great job either. On the solid-waste front, one model from Kohler clogged 25 percent of the time, and one from Briggs clogged half the time. But we did find two good sub-$300 performers from Gerber and Kohler. Do the job yourself, as detailed in this Weekend Project, and you might save enough to buy a top model in our ratings (available to subscribers).—Gian Trotta | e-mail | Twitter | Forums | Facebook

Essential information: Read about the latest water-saving showerheads. Our recent tests of toilet paper found two brands that could save you up to $130 a year.