Gravity

• Many toilets in use today are gravity flushing toilets, which use gravity to flush waste out of the toilet's bowl. Water fills to a certain level in the toilet's tank, which sits above the bowl. When you press the handle on the toilet's tank, the cover over the drain hole in the bottom of the tank lifts and the water in the tank rushes down into the bowl with the force of gravity. The new water forces the old water and waste through the curving trap in the toilet's drain line. The cover falls back over the toilet tank's drain hole and the tank refills with water in preparation for the next flush.
  
  

Low Flow

• Low flow toilets have a smaller tank than toilets of the past, meaning they use less water per flush. In the United States, low flow toilets became a requirement in 1994. The first generation of low flow toilets did not flush with as much power as traditional toilets. Partway through 1997 the second generation of low flow toilets started, with design improvements that improved flushing power.
  
  

Automatic

• Automatic toilets detect movement and the presence of a person on the toilet's bowl. When the person moves off of the bowl, the toilet's sensor sends feedback to the flush mechanism so the toilet flushes automatically. Public restrooms may use automatic flushing toilets to keep the toilets clean for longer periods of time.
  
  

Dual Flush

• Dual flush toilets allow the user to choose how much water he wants to use each flush. Two buttons sit on the top of the toilet's tank. One button uses only part of the water in the tank, for flushing just urine out of the bowl. The other button uses all of the water in the tank, useful for flushing solid waste down the toilet's drain.
  
  

Pressure Assisted

• Unlike gravity flush toilets, pressure assisted toilets pressurize the water in the toilet's tank so they flush with greater force. An airtight pressure chamber sits inside the toilet's tank. As water fills up the bottom of the pressure chamber, the air in the chamber compresses in the top. The more water that fills the chamber the more pressurized the air becomes. When the chamber opens to let the water out, the pressurized air forces it out of the chamber and into the bowl.