Best Management Practice: Toilets and Urinals
toilets and urinals can account for nearly one-third of a building’s
water consumption. Inefficient or poorly maintained toilet and urinal
fixtures can be a major source of water waste in commercial,
residential, and institutional buildings; thus, significant savings are
possible in this area.Several types of toilets and urinals are available for residential, commercial, and industrial use. Builders, plumbers, and agencies need to ensure that fixtures are water efficient and that they choose the most appropriate fixture for specific applications.
Toilets
Two common product categories of toilets are tank, which are typically found in residential buildings and flushometer, which are common in commercial buildings.- Tank Toilets: Two common types of tank toilets are:
- Gravity-style. This type of toilet sends water from the tank into
the bowl by releasing a flapper valve between the tank and the bowl.
- Pressure-assisted. This type of toilet has a vessel inside the tank
with pressurized air. When the toilet is flushed, the pressurized air
pushes the water into the bowl at a high velocity to create a powerful
flush.
- Gravity-style. This type of toilet sends water from the tank into
the bowl by releasing a flapper valve between the tank and the bowl.
- Flushometer Toilets: Flushometer toilets send pressurized water directly from the supply line through a flush valve and into the bowl to create the flush.
Urinals
The two main types of urinals are flushometer and nonwater.- Flushometer Urinals: Flushometer urinals send
pressurized water directly from the supply line through a flush valve
and into the urinal fixture to create the flush.
- Nonwater Urinals: A nonwater urinal does not flush water but has a cartridge in the bottom that contains a sealant whereby waste flows through the cartridge and into the drain line.
Flushometer Flush Valves
Two common types of flush valves for flushometer toilets and urinals are diaphragm and piston valves.Sensors
Flushometer toilets and urinals can be equipped with electronic sensors that automatically flush the fixture. Automatic flushing toilets and urinals do not save water; rather, they are intended to provide health and sanitary benefits because the user does not have to touch the flushing mechanism.Diaphragms and Piston Valves
Flushometer toilets and urinals contain a flush valve. Two common types of flush valves are diaphragm and piston valves.- Diaphragm Valves: A diaphragm valve has a rubber
disk or diaphragm that separates the upper and lower chambers in the
valve housing. When the toilet is flushed, the relief valve is tilted.
This creates a pressure imbalance in the valve that allows the diaphragm
gasket to flex and thereby moves water at a consistent flow rate
through the valve and into the bowl. Immediately after the flush, water
fills the upper valve chamber through the diaphragm’s bypass orifice,
which is a small hole in the gasket. As water enters the bypass orifice,
the water pressure differential between the upper and lower chambers
pushes the diaphragm back into place. This seals the valve and shuts off
the water flow. A dirty or brittle gasket may not seal properly and
should be replaced. If the water pressure is not sufficient, the
diaphragm may not fully seal. This can cause the valve to remain open
resulting in continuous water flow.
- Piston Valves: A piston valve has a plastic or brass contoured cup bordered with a narrow rubber lip seal that separates the upper and lower chambers in the valve housing. When the toilet is flushed, the relief valve is tilted. This creates a lower pressure in the upper chamber, which causes the contoured cup (acting as a piston) to rise and allows water to flow quickly from the inlet pipe, under the piston, and into the bowl. Immediately after the flush, a small water stream flows through a bypass orifice in the piston to restore water and pressure to the upper valve chamber. This return of pressure subsequently pushes the piston assembly down to shut off the water flow. A piston valve may contain a debris screen that may help to limit clogging in the bypass orifice. However, the piston can leak water through the relief valve and may not seal properly if the rubber seal is worn. The piston valve remains closed under conditions of low water pressure.
Agencies should develop a regular maintenance program to maintain water efficiency in toilets and urinals.
Tank Toilets
- Ensure the water in the tank is set to the manufacturer’s recommended level and is not running over the overflow tube.
- Adjust the float if water level is too high.
- Ensure that the fill valve (the mechanism that refills the tank
after each flush) is working properly and not running constantly.
- Periodically test the flapper valve for leakage and repair if necessary:
- Drop dye or food coloring into the tank water.
- Wait 10 minutes to see if the dye has seeped into the bowl through the flapper valve.
- If the dye has seeped, ensure that the flapper valve properly drops after a flush.
- Replace the flapper if the flapper valve is not fully dropping into place and seepage continues.
- Flush the toilet immediately after the test to avoid staining the bowl.
- Drop dye or food coloring into the tank water.
Flushometer Toilets and Urinals
- At least annually, inspect the valves and check for worn parts. Long
flush cycles or continuously running valves may indicate a clogged
bypass orifice in the valve or improper sealing. The flush valve insert
may need to be cleaned or replaced. (The flush cycle of a 1.6-gpf
flushometer toilet or a 1.0-gpf urinal should not exceed 4 to 5
seconds.) A flushometer valves may include a debris screen, which can
limit clogging of the bypass orifice. For further details, see Diaphragm
and Piston Valves above.
- When replacing a flush valve insert, make sure the flush rating of
the replacement part matches the valve’s flush volume specification. For
example, a 1.6-gpf flushometer toilet should only be retrofitted with a
1.6-gpf rated flush valve insert. This is particularly important for
diaphragm valves because different rated diaphragms may be substituted
in an existing valve that increases the flush volume.
- Ensure that the building’s water pressure meets the
manufacturer-specified minimum pressure. Generally, diaphragm valves
operate at 30 to 80 pounds per square inch; piston valves operate at 15
to 80 pounds per square inch.
- Calibrate automatic sensors to ensure they are set properly to limit double or "phantom" flushing.
Nonwater Urinals
- Clean and replace the sealant, cartridges, and material according to the manufacturer’s recommendations.
- Educate users about the urinal’s water-saving benefits and ensure they are aware that water and other liquids should not be poured into the fixture because it can rinse out the sealant.
- For flushometer fixtures, do not retrofit only the toilet or urinal
flush valves with high-efficiency valves. These retrofits will cause the
fixture to flush improperly if the bowl is designed to handle more than
1.6 gpf for toilets or 1.0 gpf for urinals. Always replace the bowl and
valve when retrofitting to high-efficiency fixtures.
- Infrared or ultrasonic sensors that automatically flush flushometer valve toilets and urinals do not save water. Rather, these devices make toilet and urinal operation fully "hands free."
- Make sure maintenance staff are aware of each type of fixture’s maintenance and repair requirements.
- Establish a user-friendly method to report leaks.
When considering the replacement of toilets and urinals, research and
assess the site’s waste lines, water pressure, water quality, use
patterns, and types of users (employees, residents, occasional members
of the public, frequent visitors, etc.) to identify the appropriate
fixtures.
The following replacement options help to maintain water efficiency across facilities.
The following replacement options help to maintain water efficiency across facilities.
- Replace residential tank-type toilets with WaterSense-labeled products that have an effective volume of 1.28 gpf or lower.
- Replace flushometer-type toilets with high-efficiency toilets that use no more than 1.28 gpf.
- Replace urinals with WaterSense-labeled products or equivalent
models that are designed to use 0.5 gpf or less. HEUs use as little as
0.125 gpf.
- Ensure that the toilet and urinal valve and bowl have compatible flushing capacities.
- When deciding between a diaphragm and piston flush valve type for flushometer toilets and urinals, consider valve design, restroom traffic, water quality, and operating system characteristics. For further details, see Diaphragm and Piston Valves and Operation and Maintenance above.
- When possible, recycle used parts such as tank trim and metal flush valves (only the interior mechanism needs to be replaced) to minimize landfill impacts.
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