PRESSURE-ASSISTED

VACUUM-ASSISTED

Best for large families, kids, and heavy use, where clogs are likeliest. Creates the most flushing power, as pressure created when water displaces air within a sealed tank causes the water to thrust waste forcefully out through the bowl.

But they can be loud, a potential annoyance in small homes or for those in rooms near a bathroom. These toilets require at least 25 pounds per square inch of water pressure to work well.

Best for close quarters where quietness counts. A vacuum chamber inside the tank works like a siphon to pull air out of the trap below the bowl so that it can quickly fill with water to clear waste.

But while some vacuum models performed well in past tests, the latest we tested had far less flushing power than pressure-assisted toilets yet typically cost as much. Fewer vacuum models sold also means fewer choices.

Best for those who want a quiet, proven design or have low water pressure. These rely on water dropping from the tank into the bowl and trap to move waste down the drain. Pressure as low as 10 pounds per square inch is adequate, since gravity does all the work.

But models that approach pressure-assisted performance typically cost just as much, while lower-priced models often aren't up to the job.