WaterSense
at Work
Sanitary Fixtures and Equipment
3.1 Toilets (Water Closets)
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Best Management Practices for
Commercial and Institutional Facilities
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EPA
WaterSense
May 2023
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WaterSense® is a voluntary partnership program sponsored by the U.S. Environmental
Protection Agency (EPA) that seeks to protect the nation's water supply by transforming
the market for water-efficient products, services, and practices.
WaterSense at Work is a compilation of water efficiency best management practices
intended to help commercial and institutional facility owners and managers from multiple
sectors understand and better manage their water use. It provides guidance to help
establish an effective facility water management program and identify projects and
practices that can reduce facility water use.
An overview of the sections in WaterSense at Work is below. This document, covering
water efficiency for toilets, is part of Section 3: Sanitary Fixtures and Equipment. The
complete list of best management practices is available at
www.epa.gov/watersense/best-management-practices. WaterSense has also developed
worksheets to assist with water management planning and case studies that highlight
successful water efficiency efforts of building owners and facility managers throughout
the country, available atwww.epa.gov/watersense/commercial-buildings.
• Section 1. Getting Started With Water Management
• Section 2. Water Use Monitoring
• Section 3. Sanitary Fixtures and Equipment
• Section 4. Commercial Kitchen Equipment
• Section 5. Outdoor Water Use
• Section 6. Mechanical Systems
• Section 7. Laboratory and Medical Equipment
• Section 8. Onsite Alternative Water Sources
EPA 832-F-23-003
Office of Water
U.S. Environmental Protection Agency
May 2023
This document is one section from WaterSense at Work: Best Management Practices for Commercial and
Institutional Facilities (EPA-832-F-23-003). Other sections can be downloaded from
www.epa.gov/watersense/hest-management-practices. Sections will be reviewed and periodically updated
to reflect new information. The work was supported under contract 68HERC20D0026 with Eastern Research
Group, Inc. (ERG).
May 2023
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Sanitary Fixtures and Equipment
Toilets (Water Closets)
Overview
Toilets, or water closets, can be found in nearly every commercial and institutional facility.
Several types of toilet technologies are installed in commercial and institutional settings,
including tank-type toilets, flushometer-valve toilets, and less commonly, composting
toilets. Toilets currently on the market can perform well (i.e., adequately clear waste)
while using much less water than older models installed before the Energy Policy Act
(EPAct) of 1992 established maximum flush volume requirements.
Tank-type toilets are designed with tanks that store and dispense water to the toilet bowl
to flush waste. Varieties of tank-type toilets include: the standard gravity type {found in
most homes); pressure-assist (or flushometer-tank toilets); and electromechanical
hydraulic toilets. Tank-type toilets are available as single-flush models or dual-flush
models, which include a full flush for solids and a reduced flush for liquids. Tank-type
toilets are commonly found in residential and light commercial settings.
Flushometer-valve toilets are tankless fixtures with either wall-
or floor-mounted bowls attached to a lever- or sensor-activated
flushometer valve that releases a specific volume of water at a
high flow rate directly from the water supply line to the bowl to
remove (i.e., flush) waste. Unlike tank-type toilets, which store
water in the tank to provide the necessary head pressure and
flow to remove waste from the bowl, flushometer-valve toilets
rely on larger diameter water supply piping and high water
supply line pressures to remove waste. These fixtures are also
available as single- or dual-flush models. Flushometer-valve
toilets are used predominantly in public-use facilities and high-
use commercial settings. Flushometer-valve toilets include
bowls that operate with a siphonic action, common to most
commercial restrooms, as well as blowout and rear discharge
bowls that are commonly found in prisons or other types of
institutional facilities.
Flushometer-valve toilets can be equipped with electronic sensors that trigger the flushing
mechanism when a user has finished using the fixture. Sensors themselves provide no
additional water efficiency benefits; however, they provide health and sanitation benefits
in public-use facilities, since they offer a hands-free option. If not properly programmed,
operated, and maintained, automatic flush sensors can cause unnecessary double or
"phantom" flushing, which increases the water used at a facility. EPAct 1992 established
the maximum allowable flush volume for gravity tank-type, flushometer tank (or pressure-
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Flushometer-valve toilet
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assist), electromechanical hydraulic, and flushometer-valve
toilets sold in the United States at 1.6 gallons per flush (gpf)
(6.1 liters per flush [Ipf]). The maximum flush volume was set
at 3.5 gpf (13.2 Ipf) for blowout toilets, which are used
primarily in locations subject to high traffic or heavy use such
as prisons. Due to the long, useful life of toilets, many toilets
in use today are older and have flush volumes of 3.5 gpf to 5.0
gpf (13.2 Ipf to 18.9 Ipf).
To further address efficiency and advances in toilet
technology, the U.S. Environmental Protection Agency's
(EPA's) WaterSense® program published the WaterSense
Specification for Tank-Type Toilets and the WaterSense
Specification for Flushometer-Valve Water C/osefs.1'2
WaterSense labeled tank-type toilets use 1.28 gpf (4.85 Ipf) or WaterSense labeled
less. For dual-flush tank-type toilet models, WaterSense tank-type toilet
labeled toilets can have a full flush up to 1.6 gpf (6.1 Ipf);
however, the reduced flush must use 1.1 gpf (4.2 Ipf) or less to ensure that the average of
one full flush and two reduced flushes is equal to or less than 1.28 gpf (4.85 Ipf). All
WaterSense labeled flushometer-valve toilets, including both single- and dual-flush
models, must use no more than 1.28 gpf (4.85 Ipf) and no less than 1.0 gpf (3.8 Ipf) in full
flush mode. WaterSense set a minimum flush volume for flushometer-valve toilets so that
labeled models have enough flow to adequately clear commercial building drainlines.
Both types of toilets are also independently certified to remove at least 350 grams of solid
waste per flush, helping to ensure product performance.
While EPAct 1992 established the maximum allowable flush volume for toilets at the
national level, some states and municipalities have adopted regulations mandating that
toilets have a flush volume of 1.28 gpf (4.85 Ipf) or less, consistent with the WaterSense
specifications.3 It is important to note that while some of these regulations establish flush
volume criteria consistent with the WaterSense specifications, they may not require
products to be WaterSense labeled or to meet WaterSense's performance criteria.
Looking for the WaterSense label when purchasing toilets will ensure that the product
meets both efficiency and performance criteria.
Composting toilets are a less common alternative to typical water-using toilets. They are
toilets that include an anaerobic processing system that can treat waste using little to no
flush water. These toilets do not send the waste through the sanitary sewer for treatment
at a wastewater treatment plant, although some applications treat the toilet waste in an
1 U.S. Environmental Protection Agency's (EPA's) WaterSense program. Residential Toilets.
www.epa.gov/watersense/residential-toilets.
2 EPA's WaterSense program. Commercial Toilets, www.epa.gov/watersense/commercial-toilets.
3 Appliance Standards Awareness Project. State Standards, https://appliance-standards.org/states.
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onsite septic system. Composting toilets are not included in the scope of the WaterSense
toilet specifications.
Operation, Maintenance, and User Education
Facility managers can reduce water use by taking simple
steps to educate users on proper toilet use and
maintenance. In addition, consider the following:
• Post signage and train users to report continuously
flushing, leaking, or otherwise improperly operating
toilets to the appropriate personnel.
• Educate and inform users with restroom signage and
other means to avoid flushing inappropriate objects,
such as feminine products, wrappers, paper towels,
wipes, trash, or other objects. Make it easy for users to dispose these items that
should not be flushed, and train custodial staff on how to handle the inappropriate
disposal of such objects.
• If the facility uses dual-flush toilets, include educational signage about the use of
the reduced flush for liquid waste. Make sure the proper directions for activating
the full and reduced flushes are clearly labeled on the toilet itself or in the stall.
In addition, consider the operation and maintenance tips below specific to tank-type
toilets and flushometer-valve toilets.
Tank-Type Toilets
• Periodically check to ensure fill valves are working properly and the water level is
set correctly. Remove the toilet tank lid and check to see if water is flowing over the
top of the overflow tube inside the tank. Ensure that the refill water level is set one
inch below the top of the overflow tube. Adjust the float lower if the water level is
too high. If the toilet continues to run after the float is adjusted, replace the fill
valve. In order to prevent changes in tank water levels due to line water pressure
fluctuations, only replace existing fill valves with pilot-type fill valves.
• Annually test toilets to ensure the flappers are not worn or allowing water to seep
from the tank into the bowl and down the sewer. Drop a dye tablet or several drops
of diluted food coloring in the tank. After 10 minutes, see if the dye has leaked into
the bowl, which indicates water is also leaking into the bowl. Flush the toilet
immediately after conducting this test to ensure the dye does not stain the tank or
bowl. If there is a leak, check for a tangled chain in the tank or replace a worn
flapper or the complete valve. When replacing a flapper, be sure to get the correct
type for the toilet model. If leaking does not subside after a flapper is replaced,
Example dual-flush signage
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consider replacing the flapper seat and overflow tub assembly, which could also be
worn.
• Learn more by watching leak detection and repair videos posted on the
WaterSense Fix a Leak Week web page at www.epa.gov/watersense/fix-leak-week.
Flushometer-Valve Toilets
• At least annually, inspect diaphragm or piston valves and replace any worn parts.
To determine if the valve insert needs replacement, determine the time it takes to
complete a flush cycle. The flush volume of a flushometer-valve toilet can be
estimated by counting the number of seconds it takes from activation until the
valve closes.4 Use Equation 1 below. For example, a properly functioning 1.6 gpf
(6.1 Ipf) flush valve should not have a flush cycle longer than four seconds. If the
calculated flush volume greatly exceeds the rated flush volume of the toilet,
replace the diaphragm or piston valve insert.
Equation 1. Flush Volume of Flushometer-Valve Toilet (gallons per flush)5
= Time to Flush x 0.42
Where:
• Toilet Flush Volume: Gallons per flush
• Time to Flush: Seconds per flush
• If replacing valve inserts, make sure the replacements are consistent with the valve
manufacturer's specifications, including the rated flush volume. If replacing the
entire valve, make sure it has a rated flush volume consistent with manufacturer
specifications for the existing bowl.
• Periodically check to ensure the control stop (which regulates the flow of water
from the inlet pipe to the flushometer valve and is necessary for shutting off the
flow of water during maintenance and replacement of the bowl or valve) is set to
fully open during normal operation.
• Upon installation of a flushometer-valve toilet, adjust the flush volume following
the manufacturer's instructions to ensure optimum operation for the facility's
specific conditions. Periodically inspect the flush volume adjustment screw to
ensure the flush volume setting has not been modified from the original settings; if
it has, it could change the water use and performance of the product.
4 South Florida Water Management District. 2013. Water Efficiency and Self-Conducted Water Audits at
Commercial and Institutional Facilities: A Guide for Facility Managers, www.sfwmd.gov/document/water-
efficiency-anrt-self-conrtuctert-water-aurtits-commercial-anrt-institutional-facilities.
5 Multiply number of seconds by 1.59 to get liters per flush.
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• Ensure that the line pressure serving the flushometer-valve toilet meets the
minimum requirements specified by the fixture manufacturer,
• If automatic sensors are installed, check and adjust them to ensure proper settings
and operation and avoid double or phantom flushing.
Retrofit Options
To retrofit an existing toilet to increase water efficiency, consider the following options for
tank-type and flushometer-valve toilets:
Tank-Type Toilets
In general, avoid retrofitting existing tank-type toilets with displacement dams or bags,
early-closing toilet flappers, or valves with different flush volumes, as these devices could
impede overall performance and require increased operation and maintenance. In
addition, using these devices and other retrofit products could actually increase water
consumption and void manufacturer warranties.
Flushometer-Valve Toilets
Some recently developed bowls function satisfactorily at a range of flush volumes. For
example, a 1.6 gpf (6.1 Ipf) bowl may be coupled with either a 1.6 gpf (6.1 Ipf) valve or a
1.28 gpf (4.85 Ipf) valve. Similarly, a newer 1.28 gpf (4.85 Ipf) bowl might perform
satisfactorily at both 1.28 gpf and 1.1 gpf (4.85 Ipf and 4.2 Ipf). Review the markings on the
bowl or check with the bowl manufacturer to determine if that is the case with the bowl
being considered. If it is the case, consider installing valve inserts with a lower flush
volume rating to reduce water use from flushometer-valve toilets. However, first consider
piloting the retrofit in a limited number of toilets to ensure both toilet and drain line
performance are maintained before expanding to the whole facility.
For older flushometer-valve toilets with higher flush volume (e.g., 3.5 gpf [13.2 Ipf] or
greater), it is generally best to avoid piecemeal retrofit options, such as valve inserts, that
reduce the flush volume of flushometer-valve toilets. These products might not provide
the expected performance if the original bowl is not designed to handle a reduced flush
volume. In addition, the use of these devices could void manufacturer warranties.
Dual-flush conversion devices are available for
flushometer-valve toilets. These devices usually replace
the existing flush valve handle with a handle that provides
a reduced flush volume for liquids and a standard flush for
solids. When considering this type of retrofit, verify that the
product has been certified to International Association of
Plumbing and Mechanical Officials (IAPMO) PS 50-2019,
Flush Valves with Dual-Flush Device for Water Closets or
Water Closet Tank with an Integral Flush Valves with a
Dual-flush toilet handle
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Dual-Flush Device. In addition, before initiating a full-scale retrofit, test the product on a
select number of toilets to verify it achieves and maintains the desired performance.
Replacement handles come in two different designs: handles in which an upstroke is
required to initiate the reduced flush, and the reverse, where the reduced flush is
activated with a down stroke. Consider the behavior of the users when making a selection,
because the correct design approach for your facility could have a significant effect upon
water use. For example, some users, particularly in public or heavy traffic restrooms, may
use their foot to depress the handle, so a reduced flush on a down stroke may be more
appropriate. Monitoring the water usage after replacement or piloting different options
may provide insight on the best choice. Educational signage communicating proper
operation of dual-flush toilets is recommended.
Replacement Options
If installing a new toilet or replacing an older,
inefficient toilet, consider the following
replacement options:
Tank-Type Toilets
When installing new tank-type toilets or
replacing older, inefficient tank-type toilets,
choose WaterSense labeled models.6
WaterSense labeled tank-type toilets are
independently certified to have an effective
flush volume of 1.28 gpf (4.85 Ipf) or less and
pass a performance test to remove at least
350 grams or more of solid waste per flush.
Flushometer-Valve Toilets
When installing new or replacing older,
inefficient flushometer-valve toilets, choose
WaterSense labeled models.6 WaterSense labeled flushometer-valve toilets, including
both single-flush models and the full flush of dual-flush models, use no more than 1.28
gpf (4.85 Ipf), which is 20 percent less than the federal standard of 1.6 gpf (6.1 Ipf).
WaterSense labeled models are also required to be independently certified for
performance. In some commercial facilities, there may be concerns about the ability of
drainlines to carry waste; however a study of drainline carry conducted by the Plumbing
Efficiency Research Coalition (PERC), a collaborative network of six plumbing
stakeholders, indicated that drainline blockages are not of significant concern at 1.28 gpf
6 Use WaterSense's product search tool at www.epa.gov/watersense/product-search to help identify
WaterSense labeled models.
Look for WaterSense
Labeled Toilets
look for
When replacing old,
inefficient toilets or
purchasing new toilets look
for the WaterSense label. A
product with the label uses
at least 20 percent less
water than standard models
and is independently certified for
performance. Looking for the label is a
simple way to quickly identify toilets that
save water and perform well. Facilities
can also use WaterSense's Product
Search Tool to find labeled toilets. Go to
www.epa.gov/watersense/product search
to get started.
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(4.85 Ipf) flush volumes.7 WaterSense included a minimum flush volume of 1.0 gpf (3.9 Ipf)
in its specification to help ensure labeled models have enough water flow to adequately
clear commercial building drainlines.
A follow-on study also done by PERC examined the impacts of
other drainline characteristics (e.g., pipe diameter, pipe slope) on
drainline performance. The study found that a steeper drainline
slope (2 percent instead of 1 percent) performed better at lower
flush volumes.8 Facility managers, especially in older buildings or
buildings with existing plumbing system issues, should consult a
plumbing engineer to determine the suitability of the existing
drainlines and plumbing system before installing flushometer-
valve toilets with lower flush volumes. A plumbing engineer can
help carefully evaluate the physical conditions of existing
drainlines and the availability of supplemental water flow
upstream from the toilet fixtures to make sure that the conditions
are appropriate for effective waste transport. Facility managers
should also consider conducting a pilot project to replace toilets i
one or two restrooms to ensure adequate performance before
implementing a full-scale replacement.
Composting Toilets
Consider installing composting toilets in facilities where connecting to a plumbing system
is cost-prohibitive or unavailable.
Savings Potential
Water savings can be achieved by replacing existing tank-type and flushometer-valve
toilets. To estimate facility-specific water savings and payback, use the following
information:
Tank-Type Toilet Replacement
Current Water Use
To estimate the current water use of an existing tank-type toilet, identify the following
information and use Equation 2 on the next page:
WaterSense labeled
flushometer-valve
toilet
1 Plumbing Efficiency Research Coalition (PERC). November 2012. The Drainline Transport of Solid Waste in
Buildings, www.plumbingefficiencyresearchcoalition.org/projects/drainline-transport-of-solid-waste-in-
buildings/.
8 PERC. March 2016. The Drainline Transport of Solid Waste in Buildings - Phase 2.0. (including
Supplemental report on PERC Phase 2.1). www.plumhingefficiencyresearchcoalition.org/projects/drainline-
transport-of-solid-waste-in-buildings/.
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• Flush volume of the existing tank-type toilet: Toilets installed after the mid-1970s
typically have standard flush volumes of 3.5 gpf or 5.0 gpf (13.2 Ipf or 18.9 Ipf).9
Toilets installed in 1994 or later have standard flush volumes of 1.6 gpf (6.1 Ipf).
• Average number of times the toilet is flushed per day, which will be dependent on
the facility's male-to-female ratio: Female building occupants use the toilet three
times per day on average, while male building occupants use the toilet once per
day on average.10
• Days of facility operation per year.
Equation 2. Water Use of Toilet (gallons or liters per year)
= Toilet Flush Volume x Number of Flushes x Days of Facility Operation
Where:
• Toilet Flush Volume: Gallons or liters per flush
• Number of Flushes: Flushes per day
• Days of Facility Operation: Days per year
Water Use After Replacement
To estimate the water use of a WaterSense labeled replacement tank-type toilet, use
Equation 2, substituting the flush volume of the replacement tank-type toilet. WaterSense
labeled toilets use no more than 1.28 gpf (4.85 Ipf) on average, with some models flushing
1.0 gpf (3.8 Ipf) or less.11
Water Savings
To calculate the water savings that can be achieved from replacing an existing tank-type
toilet, identify the following information and use Equation 3 on the next page:
• Current water use as calculated using Equation 2.
• Water use after replacement as calculated using Equation 2.
9 North Carolina Department of Environment and Natural Resources. May 2009. Water Efficiency Manual for
Commercial, Industrial and Institutional Facilities. Page 28. www.deq.nc.gov/watereducation/water-
efficiency-husiness-2/download.
10 Vickers, Amy. 2001. Handbook of Water Use and Conservation. WaterPlow Press.
11 For dual-flush models, calculate the flush volume by averaging the volume of one full flush and two
reduced flushes.
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Equation 3. Water Savings From Toilet Replacement (gallons or liters per year)
= Current Water Use of Toilet - Water Use of Toilet After Replacement
Where:
• Current Water Use of Toilet: Gallons or liters per year
• Water Use of Toilet After Replacement: Gallons or liters per
year
Payback
To calculate the simple payback from the water savings associated with replacing an
existing tank-type toilet, consider the equipment and installation cost of the replacement
tank-type toilet (including any rebates or incentives obtained from a utility that may
reduce the incurred cost), the water savings as calculated using Equation 3, and the
facility-specific cost of water and wastewater.
Flushometer-Valve Toilet Replacement
Current Water Use
To estimate the current water use of an existing flushometer-valve toilet, use Equation 2,
substituting the flush volume of the existing flushometer-valve toilet. Toilets installed after
the mid-1970s typically have standard flush volumes of 3.5 gpf or 5.0 gpf (13.2 Ipf or 18.9
lpf).12Toilets installed in 1997 or later have standard flush volumes of 1.6 gpf (6.1 Ipf).
Water Use After Replacement
To estimate the water use of a replacement flushometer-valve toilet, use Equation 2,
substituting the flush volume of the replacement flushometer-valve toilet. WaterSense
labeled flushometer-valve toilets—both single- and dual-flush models—use no more than
1.28 gpf (4.85 Ipf) in full flush mode.
Water Savings
To calculate water savings that can be achieved from replacing an existing flushometer-
valve toilet, use Equation 3.
Payback
To calculate the simple payback from the water savings associated with replacing an
existing flushometer-valve toilet, consider the equipment and installation cost of the
12 North Carolina Department of Environment and Natural Resources, op. cit.
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replacement flushometer-valve toilet, the water savings as calculated using Equation 3,
and the facility-specific cost of water and wastewater.
Additional Resources
Alliance for Water Efficiency. Toilets (Tank Type and Flush Valve).
www.allianceforwaterefficiency.org/resources/topic/toilets-tank-type-and-flush-valve.
EPA's WaterSense program. Commercial Toilets, www.epa.gov/watersense/commercial-
toilets.
EPA's WaterSense program. Fix a Leak Week, www.epa.gov/watersense/fix-leak-week.
EPA's WaterSense program. Residential Toilets, www.epa.gov/watersense/residential-
toilets.
Maximum Performance (MaP) Testing, https://map-testing.com/
North Carolina Department of Environment and Natural Resources, et al. May 2009. Water
Efficiency Manual for Commercial, Industrial and Institutional Facilities.
www.deq.nc.gov/watereducation/water-efficiency-business-2/download.
Texas Water Development Board. May 2018. Best Management Practices for Commercial
and Institutional Water Users. www.twdb.texas.gov/conservation/BMPs/CI/index.asp.
U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Federal
Energy Management Program. Best Management Practice #6: Toilets and Urinals.
www.energy.gov/eere/femp/best-management-practice-6-toilets-and-urinals.
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Disclaimer
This document was prepared as an account of work sponsored by the United States Government.
While this document is believed to contain correct information, neither the United States
Government nor any agency thereof, nor any of their employees, makes any warranty, express or
implied, or assumes any legal responsibility for the accuracy, completeness, or usefulness of any
information, apparatus, product, or process disclosed, or represents that its use would not
infringe privately owned rights. EPA hereby disclaims any liability for damages arising from the use
of the document, including, without limitation, direct, indirect, or consequential damages
including personal injury, property loss, loss of revenue, loss of profit, loss of opportunity, or other
loss. Reference herein to any specific commercial product, process, or service by its trade name,
trademark, manufacturer, or otherwise does not necessarily constitute nor imply its endorsement,
recommendation, or favoring by the United States Government nor any agency thereof. The views
and opinions of authors expressed herein do not necessarily state or reflect those of the United
States Government nor any agency thereof.
v>EPA
United States Environmental Protection Agency
(4204M)
EPA 832-F-23-003
May 2023
www.epa.gov/watersense
(866) WTR-SENS (987-7367)
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