Toilets have two basic operational elements: (1) the intake
of water used for flushing and (2) the discharge of waste water. However, there are
different types of toilets based on the way they perform these operations. You need to
identify which type(s) of toilets are currently in your building and which is the most
appropriate type to replace them with before you make a purchased.
Gravity Tank Toilets:
Gravity tank toilets, which have a bowl and a tank, are most commonly found in residential
settings but are in some commercial/business settings. They depend on the volume of water
in the tank to flush wastes and usually require water pressure of no more than 10 - 15
pounds per square inch (psi) to operate properly. The tank and bowl are usually two
separate pieces, although this is not obvious once are in use. A few one-piece toilets are
also available. Gravity tank toilets are relatively inexpensive, with retail prices for
two-piece toilets ranging from $75 - $150 and one-piece models costing somewhat more.
Pressurized Tank Toilets:
This relatively new design uses water line pressure to achieve a higher flush velocity.
Water is not stored inside the tank, but in a tank that compresses a pocket of air and
releases pressurized water into the bowl and out the trapway. They require a minimum water
pressure of 25 psi to operate well. Retail prices for these toilets are generally over
Flush Valve Operated Toilets:
This is the type of toilet usually found in many public restrooms. These toilets have no
tank. Instead of a storage tank, this toilet uses a valve directly connected to the water
supply plumbing of a building. This valve controls the quantity of water released over
time by each flush. Flushometer valves are typically made by one manufacturer and the
china bowl by another. It is very important that there is a proper match between the valve
and the bowl when purchased. Unlike tank-type toilets, flushometer valve toilets must
accommodate different water pressures at different points in a building. Flushometer
toilets usually require a minimum water pressure of 25 - 40 psi to operate well. The are
priced at about $250 for both the valve and the bowl.
Floor-Discharge Drain Line:
This toilet is usually bolted to the floor. They can be gravity, pressurized or flush
valve type toilets.
Wall-Discharge Drain Line:
This toilet is usually attached to the wall, rather than the floor. They can be either
gravity or flush valve type toilets.