WaterSense
WaterSense® Specification for Homes, Version 2.0
Supporting Statement
WaterSense® Specification for Homes, Version 2.0
Supporting Statement
1.0 Introduction
The U.S. Environmental Protection Agency's (EPA's) WaterSense program released the first
version of its specification for labeled homes in 2009 with the WaterSense Single-Family New
Home Specification and issued modifications in 2012 and 2014 to expand the scope to
multifamily buildings and include minor revisions, respectively. The goal of the WaterSense
Labeled Homes Program is to encourage the construction and purchase of water-efficient, high-
performing homes that include water- and energy-efficient products and advanced design. The
program aims to reduce indoor and outdoor water use in homes and encourage community
infrastructure savings.
In February 2021, EPA released the WaterSense Specification for Homes, Version 2.0
(hereafter referred to simply as the WaterSense Specification for Homes, unless the version
number is necessary to include for clarity), which aims to further promote residential water
efficiency and help enable market transformation in the building industry. The specification is
applicable to single-family homes and multifamily buildings and can apply to new and existing
homes.
EPA intends for the revised WaterSense Specification for Homes to:
• Provide flexibility in the technical requirements for homes constructed to the WaterSense
specification without compromising overall water efficiency or performance.
• Ensure that WaterSense labeled homes are high-performing with regard to water efficiency
and homeowner satisfaction.
• Provide quantifiable potential water and utility cost savings for individual homeowners.
• Improve regional applicability.
• Improve collaboration with existing green building certification programs.
• Use existing infrastructure for certification and verification purposes to ease requirements for
home builders and verifiers who confirm home compliance with the specification.
• Use the WaterSense program's resources efficiently.
2.0 Current Status of Water Use in Residential Homes
New home construction is an optimal opportunity to encourage builders and homeowners to use
water-efficient products and practices. To provide perspective, there were more than 1.25
million new single-family homes and multifamily units constructed in 2019,1 representing
significant cumulative water use. By encouraging water-efficient products, appliances, and
design elements during construction, EPA intends to transform building practices to reduce
lifetime water and energy use and utility costs.
Federal regulations have addressed water use and efficiency inside the home over the past
quarter century. The Energy Policy Act of 1992 (EPAct 1992) established the maximum flush
1 U.S. Census, 2020. Monthly New Residential Construction, October 2020. November 18, 2020. Table 5b.
www.census.aov/construction/nrc/pdf/newresconst.pdf
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Supporting Statement
volume for toilets at 1.6 gallons per flush (gpf), and the maximum flow rate for bathroom sink
faucets, kitchen faucets, and showerheads at 2.5 gallons per minute (gpm). Subsequently, in
1998, the U.S. Department of Energy (DOE) adopted a maximum flow rate standard of 2.2 gpm
for all faucets. In 2012 and 2016 respectively, the DOE issued new regulations mandating
minimum water efficiency requirements for clothes washers and dishwashers.2 3 The
WaterSense and ENERGY STAR® programs promote water efficiency in plumbing fixtures and
appliances that go beyond these national standards.
Two studies completed over the past 20 years best characterize water use in the residential
sector. The American Water Works Association (AWWA) Research Foundation completed a
1999 study, Residential End Uses of Water (REUW1999),4 that provided the first detailed
analysis of residential water use patterns and efficiency levels in the United States. The Water
Research Foundation (WRF) completed an updated study in 2016, Residential End Uses of
Water, Version 2 (REUW2016),5 providing an expanded assessment and analysis of single-
family water use across North America. REUW2016 also presents updated information about
water use patterns, as compared to REUW1999. Table 2-1 summarizes the average daily per
capita indoor water use for North American homes, as identified by both residential studies.
Table 2-1. Daily Indoor Per Capita Water Use
Type of Use
Daily Indoor Water Use
(gallons per capita per day)
REUW1999
REUW2016
Toilets
18.5
14.2
Clothes washers
15.0
9.6
Showers
11.6
11.1
Faucets
10.9
11.1
Leaks
9.5
7.9
Other
1.6
2.5
Baths
1.2
1.5
Dishwashers
1.0
0.7
Total
69.3
58.6
Over the 15-year period between the two REUW studies, residential per capita indoor water use
decreased 15.4 percent. While this reduction is significant, there are still opportunities for
additional water savings. A 2011 study by William DeOreo found that new homes built with high-
2 DOE, 2012. Energy Conservation Program: Energy Conservation Standards for Residential Clothes Washers.
Direct Final Rule. May 31,2012. www.regulations.qov/document?D=EERE-2008-BT-STD-0019-0041
3 DOE, 2016, Energy Conservation Program: Energy Conservation Standards for Residential Dishwashers; Final
Rule. December 13, 2016. www.regulations.aov/document?D=EERE-2014-BT-STD-0021 -0033
4 Mayer, Peter W. et al., 1998. Residential End Uses of Water. Published by the AWWA Research Foundation and
American Waterworks Association.
5 DeOreo, William B., Peter Mayer, Benedykt Dziegielewski, and Jack Kiefer, 2016. Residential End Uses of Water,
Version 2. Published by the Water Research Foundation.
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efficiency plumbing fixtures, appliances, and design practices (considered to be roughly
equivalent to homes built to the WaterSense Specification for New Homes, Version 1.0) had an
average indoor daily per capita water use of 36.7 gallons per day, which is 37 percent more
water-efficient than North American homes surveyed for REUW2016.6 EPA intends for the
WaterSense Specification for Homes, Version 2.0 to serve as a resource to help achieve
additional household water savings.
The WaterSense Labeled Homes Program is an initiative designed to actively promote the
transformation of the mainstream homebuilding industry towards increased water efficiency.
Through the revised specification and resulting program structure, EPA intends to collaborate
directly with existing green home building programs to promote a national ethic of water
efficiency. By affirming the technical efficacy of existing home certification programs with regard
to water efficiency, WaterSense aims to raise the profile of water efficiency in the broader green
building industry. Through recognition of homes that meet specific performance and efficiency
criteria, WaterSense hopes to drive builder and consumer confidence during the home buying
process.
3.0 Definitions
For definitions related to the revised WaterSense Labeled Home Program, refer to the
WaterSense Home Certification System and WaterSense Technical Evaluation Process for
Approving Home Certification Methods.
4.0 Overview of Program Changes in Version 2.0
Motivation for Revision
Based on feedback from stakeholders, years of program operation, and changes in the home
building marketplace that have occurred over the last decade, EPA has decided to revise its
specification and certification process for WaterSense labeled homes. Since the original
specification was introduced in 2009, water-efficient products have become more accessible
and effective, and consumer demand for water-efficient homes has increased. Wth Version 2.0,
WaterSense aims to accommodate a broader network of water efficiency professionals
interested in participating in the WaterSense Labeled Homes Program, which had been limited
in the original program structure. The revision also allows WaterSense to acknowledge a
growing number of regional home certification and/or labeling programs operating across the
United States.
Wth this revision, EPA: 1) requires that homes meet a minimum set of quality performance
criteria (via a mandatory checklist); and 2) requires that homes meet an efficiency requirement
(set at 30 percent more water-efficient than a home with characteristics typical of new
construction, based on national standards, and common design and landscape practices). This
specification structure reduces the prescriptive requirements (with the exception of key
WaterSense labeled plumbing products) and focuses on WaterSense's main objective of saving
water, while allowing builder partners to choose the approach that best fits their market, and
strategy. Under the revised specification and certification structure, EPA recognizes credible
certification programs or standards that have valid approaches to demonstrate compliance with
the water efficiency requirement for homes. EPA also allows the programs to offer the
WaterSense label in ways conducive to their existing structures and the needs of their
6 DeOreo, William B, 2011. Analysis of Water Use in New Single-Family Homes.
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WaterSense
stakeholders. By encouraging other organizations to administer the program and issue the
WaterSense label in conjunction with their existing certifications, the revised specification
increases flexibility among, and access to, a larger network of home verifiers. Builder partners,
in turn, are able to choose home certification programs that suit their needs and the needs of
their customers. The flexibility inherent in the revision allows for the inclusion of regional or local
programs that could better address regional climate variability and local water efficiency
priorities.
By adding flexibility to the technical requirements, as well as to the program and certification
structure, EPA seeks to increase the reach of the WaterSense Labeled Homes Program and
make it possible for more homes to earn the WaterSense label, while maintaining an equal (or
greater) level of water efficiency and performance.
Revised Program Structure
Home Certification Organizations (HCOs) are central to the revised program structure. HCOs
are responsible for implementing a program for the verification, certification, and labeling of
homes for WaterSense. They are responsible for submitting a Proposed Certification Method
(PCM), which details the methodology and protocols the HCO intends to use to determine
whether a home meets the water efficiency requirements included in the WaterSense
Specification for Homes. Other than requiring that homes include specific WaterSense labeled
plumbing products and be free of water leaks, WaterSense does not dictate the specific
requirements that a PCM must contain or the structure under which certification is granted.
EPA evaluates and approves HCOs to ensure they have the capability, competence and proper
controls to certify and label homes for WaterSense. EPA also evaluates and approves the
HCO's PCM to ensure that: 1) the method was developed in a fair and transparent manner; and
2) homes certified in accordance with the PCM and meeting the efficiency level or requirements
the HCO has specified for WaterSense, will consistently meet WaterSense's efficiency
requirement. EPA has developed a technical evaluation process to test the PCM's technical
effectiveness, which is discussed in more detail in Section 7.0. Upon evaluation and approval by
EPA, the PCM becomes a WaterSense Approved Certification Method (WACM). Hereafter, EPA
uses the term WACM to refer to the approved certification method with the threshold or specific
requirements the HCO has designated to earn the WaterSense label. WaterSense will
periodically review WACMs for efficacy and maintain oversight of the HCOs' implementation
and use of the WaterSense label.
Home builders that partner with WaterSense can achieve certification through an HCO of their
choosing. Candidate homes must be verified and certified in accordance with the WaterSense
Specification for Homes and the HCO's WACM requirements to earn the WaterSense label.
Trained WaterSense home verifiers (verifiers) are responsible for inspecting homes to
determine whether they meet these requirements.
Documents Associated With the Revision
This supporting statement describes three documents associated with the specification revision:
the WaterSense Specification for Homes; the WaterSense Home Certification System; and the
WaterSense Technical Evaluation Process for Approving Home Certification Methods. These
three documents used in concert comprise the revised WaterSense Labeled Homes Program
structure. This supporting statement describes the purposes of the components in each
document.
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5.0 WaterSense Specification for Homes
The revised specification establishes technical criteria that homes must meet to earn the
WaterSense label. The specification contains two components: 1) the Mandatory Checklist; and
2) the water efficiency requirement.
Mandatory Checklist
In addition to an overall water efficiency requirement (discussed below), homes must meet all
requirements included on the Mandatory Checklist for WaterSense Labeled Homes, listed in
Appendix B of the WaterSense Specification for Homes. This includes WaterSense labeled
plumbing fixtures (i.e., toilets, lavatory faucets and showerheads), which have been
independently certified to perform as well or better than standard models, while also using less
water. In addition, WaterSense labeled homes are also required to pass a pressure-loss test on
all water supply lines, which indicates the absence of leaks. For a home to earn the label, there
may not be visible leaks from specified elements of the plumbing system—including the
plumbing fixtures identified above—or from other water-using systems and appliances installed
in the home at the time of verification. Leaks can adversely impact a home's water use and
result in added homeowner costs or even property damage.
The Mandatory Checklist is intended to ensure that all WaterSense labeled homes, regardless
of the HCO or WACM under which they are certified, contain a minimum set of features that will
meet homeowners' expectations for product performance. For the Mandatory Checklist, EPA
selected items that are universally applicable to all homes and have minimal incremental cost.
Although the Mandatory Checklist does not include outdoor requirements (beyond requiring
irrigation systems to be leak-free), outdoor components are still part of the revised WaterSense
homes specification. Based on the structure of EPA's technical evaluation, discussed in Section
7.0, homes with the expectation of significant outdoor water use would not meet the water
efficiency requirements without accounting for and reducing outdoor water use.
Table 5-1 presents the requirements of the Mandatory Checklist.
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Table 5-1. Mandatory Checklist for WaterSense Labeled Homes
Item
Requirements
Confirmed
Leaks
Pressure-loss test on all water supplies detects no leaks
~ Yes ~ No
Free of visible leaks from toilet(s), as determined through
visual assessment and by conducting a dye tablet test in
each toilet to ensure the flapper is not leaking
~ Yes ~ No
Free of visible leaks from bathroom faucet(s)
~ Yes ~ No
Free of visible leaks from showerhead(s)
~ Yes ~ No
Free of visible leaks from bathroom tub faucet(s), i.e., tub
spout(s), when showerhead(s) are activated, as
determined through visual assessment after
showerhead(s) have been activated for one minute
~ Yes ~ No
Free of visible leaks from kitchen and other sink faucet(s)
~ Yes ~ No
Free of visible leaks from other fixtures or appliances
(e.g., water heaters, clothes washers, dishwashers, hose
bibs, irrigation systems) at the point of use or point of
connection to water distribution system
~ Yes ~ No
Toilets
WaterSense labeled7
~ Yes ~ No
Bathroom sink
faucets
WaterSense labeled7
~ Yes ~ No
Showerheads
WaterSense labeled7
~ Yes ~ No
Efficiency Requirement
The specification stipulates that homes must be at least 30 percent more water-efficient than a
home with characteristics typical of new construction. A home's water efficiency is determined
through compliance with the HCO's WACM. WaterSense reviews and approves an HCO's
program requirements to determine if homes certified in accordance with the WACM will use 30
percent less water than homes with characteristics typical of new construction. This process is
explained in more detail in Section 7.0.
WaterSense set the water efficiency requirement at 30 percent based on analysis of typical
attributes and features in homes, common efficiency measures, and potential impacts across
different climates. WaterSense is using a percent reduction to provide flexibility while retaining
the focus on the program's primary objective of saving water. The percent reduction gives
builders flexibility to select technologies or practices best suited to their techniques, style, and
market, as long as they cumulatively achieve 30 percent water savings. The percent reduction
also scales with climate. Homes in more arid regions, for example, typically have higher annual
water usage due to irrigation demands. These homes will need to take more substantial outdoor
water efficiency measures to meet the efficiency requirement. The percent reduction can also
be easily translated to water and cost savings.
WaterSense typically requires that products be at least 20 percent more water-efficient relative
to standard products to be eligible for the WaterSense label. WaterSense has chosen to set a
higher water savings target for homes to account for indoor and outdoor water savings potential,
7 A listing of WaterSense labeled toilets, bathroom sink faucets, and showerheads can be found at
www.epa.aov/watersense/product-search.
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which cumulatively provides more opportunities for water savings. Additionally, the
homebuilding community has transformed over the past decade and has adopted many water
efficiency features as standard practice. EPA wants to encourage the market to become even
more water-efficient by recognizing homes and builders that go above and beyond.
6.0 WaterSense Home Certification System
To facilitate continued stakeholder participation in the WaterSense Labeled Homes Program
and enable a smoother transition to Version 2, EPA published a revised WaterSense Home
Certification System (Version 1.3) in May 2020. Version 1.3 of the certification system helps
bridge the gap between Version 1.2 and Version 2.0 and establishes the necessary certification
infrastructure to operate Version 2 of the WaterSense Labeled Homes Program. More
information can be found in the Explanation of Revisions to the WaterSense Home Certification
System.8
EPA subsequently instituted a pilot program to evaluate the efficacy of the draft Version 2
program requirements and specification criteria. From the implementation of the pilot, EPA
identified and made minor clarifications to the WaterSense Home Certification System, but
otherwise confirmed its functionality in the home certification marketplace and effectiveness at
meeting EPA's goals.
The WaterSense Home Certification System documents the process for certifying and labeling
homes in compliance with the WaterSense Specification for Homes. It also defines the roles and
responsibilities of parties associated with home certification and labeling, namely HCOs,
verifiers, builder partners, and EPA.
HCO Organizational Requirements
WaterSense has identified six components of certification to ensure that an HCO has a structure
in place to effectively certify homes, as well as issue and maintain the integrity of the
WaterSense label. The following section describes the purpose of each certification component
in the context of the certification system. The WaterSense Home Certification System contains
more details on the requirements associated with each component.
As part of the home certification system, HCOs are required to establish procedures to address
each of the following components:
1. Independent oversight ensures that the administration of the WACM and
certification and labeling of homes for WaterSense are governed in a fair and
impartial manner.
2. Quality assurance ensures that home verifications and certifications are conducted
in a consistent, accurate, and appropriate manner. Quality assurance helps maintain
the integrity of the WaterSense label and ensures that anticipated water savings and
home performance are realized. Quality assurance also provides a mechanism for
resolving complaints regarding home verification and/or certification.
3. Verifier training and authorization is intended to prepare verifiers to conduct
accurate and consistent verifications, complete necessary paperwork, and comply
8 EPA, 2020. Explanation of Revisions to the WaterSense Home Certification System. May 14, 2020.
www.epa.qov/sites/production/files/2020-05/documents/ws-homes-
explanation of revisions to ws home certification svstem.pdf
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with quality assurance standards. Following training and authorization, WaterSense
home verifiers should be prepared to verify a home in accordance with the
WaterSense Specification for Homes and the HCO's WACM under which they are
authorized.
4. Home verification protocols establish requirements by which the HCO and its
verifiers verify and certify homes for the WaterSense label. These protocols serve an
important function for consumers, since accurate verifications identify homes that
meet the expected water savings and performance.
5. Impartiality ensures that conflicts of interest (COI) related to the verification and
certification of homes do not exist or have been resolved. When HCOs ensure
impartiality, verifiers and designee(s) can fulfill their responsibilities in a manner that
does not compromise the integrity of the HCO's certification program or the issuance
of the WaterSense label.
6. Messaging and reporting create a link between WaterSense and HCOs. Through
clear channels of communication, WaterSense can relay program information to
stakeholders and track key program outputs.
By addressing each certification component, HCOs maintain the integrity of the WaterSense
label and ensure that homes that are certified to the WaterSense Specification for Homes
demonstrate expected water savings and performance.
Once approved, HCOs are responsible for verifying and certifying homes to the WaterSense
Specification for Homes. The HCO is permitted to delegate most responsibilities to a "designee,"
such as a provider of hired or contracted verifiers or other organization that supports adherence
to the certification requirements. However, the HCO is required to oversee all delegated
activities and retains ultimate responsibility for the verification and certification of each home.
Since controlling the use of the label is essential to certification programs such as WaterSense,
it is important that responsibility for controlling label use remains centralized with the HCO,
rather than dispersed among designees.
Some responsibilities cannot be delegated to a designee and must be executed by the HCO.
The HCO holds ultimate responsibility for issuing the WaterSense label to homes. The HCO is
also responsible for reporting information on authorized verifiers and new certified homes to
WaterSense. Section 5.0 of the WaterSense Home Certification System summarizes key
responsibilities for approved HCOs and provides logistical details to help HCOs implement each
responsibility.
HCO Certification Method Development Process
The certification system indicates acceptable approaches for HCOs to follow as they develop or
adopt a PCM. These approaches are identified to help ensure HCOs are meeting the needs of a
broad set of stakeholders. An HCO can use one of three options to demonstrate its PCM was
developed following an open and transparent process. The requirements also help EPA
conform to the National Technology Transfer and Advancement Act, which stipulates that
federal agencies rely on technical standards developed and adopted by voluntary consensus
standards bodies, as opposed to using government-unique standards. Following are three
optional approaches for HCOs to meet these requirements:
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1. Utilize an American National Standards Institute (ANSI) approved standard or
standard developed through an equivalent consensus-based standard development
process.
2. For public agencies, demonstrate compliance with the administrative and
transparency requirements associated with standards and policy development of the
jurisdiction having authority over the program.
3. Provide written documentation demonstrating that the certification method was
developed in accordance with a set of criteria, based on the ANSI Essential
Requirements,9 as presented in the WaterSense Home Certification System.
The three options ensure maximum flexibility for HCOs in the development of their PCMs, while
generally providing for the same level of openness and transparency.
HCO Application and Approval
Prospective HCOs apply to EPA to oversee the certification and labeling of homes for
WaterSense in accordance with the WaterSense Specification for Homes. As part of their
application, prospective HCOs provide supplemental documentation that indicates how the HCO
meets each certification component.
In its response to a prospective HCO's application, EPA may provisionally approve an HCO for
select elements of the organizational requirements if an HCO requires modifications to fully
adhere to EPA's organizational and certification method development process requirements.
Provisional approval allows EPA to approve HCOs that may not initially meet all organizational
requirements outlined in the WaterSense Home Certification System, provided that the HCO
agrees to meet the outstanding requirements within a certain timeframe. Provisional approval
applies to elements of the organization structure and certification method development that
might not be necessary to begin operating as an HCO but are needed to ensure proper long-
term organizational function and ability to issue the WaterSense label. EPA will not issue
provisional approval for PCMs that are unable to consistently differentiate homes that meet the
water efficiency requirement of the WaterSense Specification for Homes.
The Application for Home Certification Organization (HCO) and Proposed Certification Method
(PCM) Approval, provided on the WaterSense website, contains more details on requirements
that may be considered for provisional approval. If an HCO is provisionally approved for any
organizational requirement, EPA will work with the HCO to develop a plan that outlines the
conditions and timeline for full compliance.
HCOs that satisfactorily meet EPA's criteria are eligible to sign a licensing agreement. The
licensing agreement is the legal document between EPA and the HCO that controls the use and
distribution of the WaterSense label and formally identifies the HCO as the entity ultimately
responsible for the label. As part of this responsibility, the HCO helps maintain the integrity of
the WaterSense label. The licensing agreement also signals the HCO's and EPA's commitment
to cooperate in the administration of the WaterSense Labeled Homes Program in accordance
with the WaterSense Specification for Homes, the HCO's WACM, and the WaterSense Home
Certification System.
9 ANSI Essential Requirements: Due process requirements for American National Standards. Edition: January 2020.
www.ansi.ora/essentialreauirements/
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7.0 WaterSense Technical Evaluation Process for Approving Home Certification
Methods
Under the WaterSense Specification for Homes, EPA requires homes that earn the WaterSense
label to be at least 30 percent more water-efficient than a comparable home with characteristics
typical of new construction, based on national standards and common design and landscape
practices. The specific requirements and/or the features a home must have to meet the water
efficiency criteria are dictated by an HCO's WACM. To that end, EPA has established a
technical evaluation process to assess water savings that can be achieved through the criteria
and performance thresholds established within a PCM. EPA approves PCMs that meet the
water efficiency criteria, as demonstrated through the technical evaluation. This technical
evaluation provides assurance that the homes that ultimately earn the WaterSense label can
deliver the anticipated water efficiency.
This supporting statement generally describes the technical evaluation process and the
rationale behind EPA's approach. The WaterSense Technical Evaluation Process for Approving
Home Certification Methods provides full details on the approach and assumptions for
assessing potential water savings and approving PCMs.
Defining Reference Homes
Because home design and attributes, such as number of bedrooms (which relates to
occupancy) and lot size (which relates to landscape area), can significantly influence a home's
water use, EPA assesses a PCM's water use and savings across a series of "reference homes"
and "reference buildings." These reference homes/buildings are intended to represent a range
of physical attributes that are realistic in single-family and multifamily home construction. Water
use in each reference home and/or reference building is compared between a baseline
configuration with water use characteristics typical of new construction and a water-efficient
configuration with the "least efficient" home and landscape design expected to achieve
certification under the PCM. The intent is to assess the PCM's ability to differentiate homes that
can meet the water efficiency requirement across a broad potential range of home designs and
physical attributes. The WaterSense Technical Evaluation Process for Approving Home
Certification Methods provides more details on the features and attributes of each reference
home and reference building.
EPA identified features to include in its reference homes from the U.S. Department of Housing
and Urban Development (HUD) 2017 Survey of Construction, and reviewed U.S. Census data
to identify typical design attributes, such as number of bedrooms, bathrooms, and lot size. EPA
used this data to estimate the prevalence of the water-using design features in single-family and
multifamily construction, including number of plumbing fixtures (toilets, lavatory faucets, kitchen
faucets), appliances (clothes washers, dishwashers), and landscaped area.
For each reference home, EPA also estimates a theoretical irrigation requirement based on the
geographic scope of the specific PCM. The requirement takes into account the local modified
net evapotranspiration (NetET0) which incorporates reference evapotranspiration, rainfall, and
specific watering months. For larger regional or national-scale programs, the reference home
uses the applicable range of modified NetET0 and rainfall values. This enables EPA to more
accurately evaluate and assess savings associated with the outdoor water use and the balance
between indoor and outdoor use based on the potential geographic area where the PCM may
be applied.
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Determining the "Least Efficient" Home and Landscape Design
EPA reviews the requirements of the PCM and defines and evaluates water savings for one or
more home and landscape designs based on the minimum requirements a home needs to meet
to achieve the PCM's proposed designation for WaterSense. These home and landscape
designs represent the criteria that potentially result in the "least efficient" homes that can earn
the WaterSense label. The features of the "least efficient" home designs are incorporated into
the assumptions and form the basis for the water-efficient configurations. This conservative
approach provides assurance that homes with a variety of configurations certified under the
PCM are able to meet or exceed the 30 percent water efficiency requirement established in the
WaterSense Specification for Homes.
Assessing Water Savings Over a Baseline Configuration
For each reference home, EPA evaluates indoor and outdoor water use associated with a
baseline configuration that includes characteristics typical of new construction (based on
national standards and common design and landscape practices) and compares it to a water-
efficient configuration that has the characteristics represented in the "least efficient" home
design(s) for the PCM.
This technical evaluation assesses water use and savings for specific features for which EPA
has identified studies, research, or other data that suggest quantifiable savings can be achieved
from implementation of that feature. Wherever possible, EPA utilized industry-recognized
studies, such as the Water Research Foundation's REUW2016 (cited above), to identify water
use, water savings, or water use patterns of different fixtures, appliances, or systems. EPA
otherwise based savings estimates on the best available data.
Table 7-1 lists the features for which EPA currently assesses savings in the technical
evaluation. The specific calculations and assumptions for assessing water use in the baseline
and water-efficient configurations are detailed in the WaterSense Technical Evaluation Process
for Approving Home Certification Methods.
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WaterSeilSe Supporting Statement
Table 7-1. Features Impacting Water Use in Baseline and/or Efficient Configurations
Under Technical Evaluation
Indoor
Outdoor
• Toilets
• Showerheads
• Lavatory faucets
• Kitchen faucets
• Clothes washers
• Dishwashers
• Bathtubs
• Hot water delivery/recirculation system
• Thermostatic shutoff valves in showers
• Leaks and leak detection systems
• Other (if applicable)
• Plant type(s) (i.e., turf, shrubs/ornamentals,
xeriscape)
• Irrigation type (s) (i.e., spray or
microirrigation)
• WaterSense labeled spray sprinkler bodies
(with integral pressure regulation) or
pressure-regulating valve
• Irrigation scheduling technologies, including:
o WaterSense labeled weather-based
irrigation controller
o Soil moisture-based irrigation controller
(soil moisture sensor)10
o Rain shutoff device (rain sensor)
• Efficient irrigation design or professional
irrigation audit
• Residential Irrigation Capacity Index (RICI)
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8.0 Specification Transition
The WaterSense Specification for Homes, Version 2.0 and the WaterSense Home Certification
System, Version 2.0 are effective as of February 2021. Prospective HCOs can apply to oversee
the certification and labeling of homes for WaterSense by submitting a completed Application for
Home Certification Organization (HCO) and Proposed Certification Method (PCM) Approval to
EPA.
Concurrent with the release of materials related to Version 2 of the WaterSense Labeled Homes
Program, EPA published a document to summarize the transition. As discussed in the
WaterSense Labeled Homes Program Transition to Version 2, HCOs previously approved by
EPA under Version 1.3 of the WaterSense Home Certification System and the Version 2 pilot
program will have their approval extended under Version 2 of the program. Therefore, as of
February 2021, builder partners can coordinate with approved HCOs and/or their approved
verifiers to certify and label homes in accordance with the WaterSense Specification for Homes,
Version 2.0.
10 EPA recently published the WaterSense Specification for Soil Moisture-Based Irrigation Controllers. Once sufficient
labeled products become available on the market, as part of future minor revisions to the WaterSense Technical
Evaluation Process for Approving Home Certification Methods, EPA intends to require these products be WaterSense
labeled to be credited for their water efficiency.
11 The RICI score is a ratio based on the sum of flow rates for each irrigation valve and the irrigated area. In the most
basic terms, the higher the RICI score, the higher the anticipated irrigation water use. More information is presented
in the WaterSense Technical Evaluation Process for Approving Home Certification Methods.
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Details of EPA's continued support of the WaterSense New Home Specification, Version 1.2,
and the transition period to Version 2 of the WaterSense Labeled Homes Program are
described in greater detail in the WaterSense Labeled Homes Program Transition to Version 2.
9.0 Potential Water, Energy, and Cost Savings
The structure of the WaterSense Specification for Homes assures EPA that homes that earn the
WaterSense label have demonstrated they will be at least 30 percent more water-efficient than
homes with characteristics typical of new construction. However, because indoor water use is
largely dependent on occupancy, and outdoor water use can vary greatly depending on local
climate and landscape size, it can be challenging to pinpoint the average water use typical of
new construction.
Water Savings
To quantify household water savings for a WaterSense labeled home, EPA uses its technical
evaluation process and tool (described in more detail in Section 7.0). However, in place of the
reference homes, EPA assumes a national average household occupancy of 2.61 occupants
per household12 and an average landscape size of 5,826 square feet.13
Depending on local climate, EPA estimates annual water use for an average home of typical
new construction could be between 102,200 gallons of water per year (approximately 42,700
gallons indoor and 59,500 gallons outdoor) and 256,900 gallons of water per year
(approximately 42,700 gallons indoor and 214,200 gallons outdoor). EPA estimates that homes
built to the water efficiency requirement (i.e., at least 30 percent more water-efficient compared
to homes with characteristics typical of new construction) could therefore save between 30,600
gallons and 77,100 gallons of water annually.
For the purposes of estimating potential national water savings, EPA assumes average
household water savings of 53,850 gallons of water per year. Extrapolated to the national level,
if 10 percent of newly constructed single-family homes in the United States earned the
WaterSense label,14 potential estimated annual water savings across the program could be up
to 4.9 billion gallons of water (see Calculation 1).
Calculation 1: National Water Savings Potential
53,850 gallons savings per year per home15 x 90,300 homes16 = 4.9 billion gallons of water
Energy Savings
The energy savings of a WaterSense labeled home varies depending on the water-efficient
design and features of the WACM. The energy savings in a WaterSense labeled home are a
12 U.S. Census Bureau. 2019 American Community Survey 1-Year Estimates.
13 DeOreo, William B., Peter Mayer, Benedykt Dziegielewski, and Jack Kiefer, 2016. Residential End Uses of Water,
Version 2. Published by the Water Research Foundation. Table 6.31.
14 This is representative of the approximate market share of the ENERGY STAR Certified Homes Program.
www.eneravstar.aov/newhomes/enerav star certified new homes market share
15 Assumed average savings based the range of estimated water savings achievable by improving water efficiency by
30 percent.
16 Based on U.S. Census Bureau, Characteristics of New Single-Family Houses Completed, 2019. In 2019, 903,000
single-family homes were completed.
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result of the decrease in the overall hot water use from more efficient distribution, fixtures, and
appliances. Therefore, energy savings would primarily be associated with indoor efficiency
measures, specifically hot water savings from installation of water-efficient showerheads,
lavatory and kitchen faucets, dishwashers, clothes washers, and reduction in structural and/or
behavioral waste from hot water delivery.
To estimate potential energy savings, EPA assumes that a home achieves a 30 percent
reduction in total indoor water use (see Calculation 2), and that 33.2 percent of this water is hot
(based on the breakdown of hot and cold water use identified in REUW2016,17 see Calculation
3).
Calculation 2: Estimated Indoor Water Savings per Household
42,700 gallons of indoor water use per year x 30 percent water savings
= 12,800 gallons of indoor water savings per year
Calculation 3; Estimated Hot Water Savings per Household
12,800 gallons of indoor water savings per year x 33.2 percent hot water
= 4,250 gallons of hot water saved per year
This expected hot water savings results in 718 kilowatt-hours (kWh) of electricity savings or 3.67
thousand cubic feet (Mcf) of natural gas savings each year (see Calculation 4 and Calculation
6).
Calculation 4: Electricity Savings per Household From Hot Water Savings
kWh
4,250 gallons ofhotwater saved per year x 0.169—-—
gallon
= 718 kWh of electricity savings per year
Water heating consumes 0.169 kWh of electricity per gallon of water heated (see Calculation 5),
assuming:
• Specific heat of water =1.0 British thermal units per pound (Btu/lb) °F
• 1 gallons of water = 8.34 lbs
• 1 kWh = 3,412 Btus
• Incoming water temperature is raised 64.5°F18
• Water heating process is 93.1 percent efficient electric hot water heating19
17 DeOreo, William B., Peter Mayer, Benedykt Dziegielewski, and Jack Kiefer, 2016. Residential End Uses of Water,
Version 2. Published by the Water Research Foundation. Table 6.25.
18 Chen, Y., H. Fuches, J. Schein, V. Franco, H. Stratton, and C. Dunham, 2020. Calculating Average Hot Water
Mixes of Residential Plumbing Fixtures. Lawrence Berkeley National Laboratory, Energy Analysis and Environmental
Impacts Division. Table 3, Page 8.
19 EPA, 2020. Data and Information Used by WaterSense. www.epa.gov/watersense/data-and-information-used-
watersense#Savinqs%20from%20Avoided%20Water%20Heatinq. Based on data from the Air Conditioning, Heating,
& Refrigeration Institute (AHRI).
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Calculation 5: kWh of Electricity per Gallon of Water Heated
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home22 (see Calculation 10). If 10 percent of newly constructed single-family homes in the
United States earned the WaterSense label, national energy savings could exceed 42 million
kWh and 176 million cubic feet (MMcf) of natural gas each year (see Calculation and
Calculation 12).
These calculations are based on the following assumptions:
• Approximately 47 percent of new homes in the United States heat their water using
electricity, and 53 percent heat their water using natural gas.23
• Approximately 89 percent of households in the United States are connected to a public
water supply.24
• Approximately 83 percent of households in the United States are connected to a public
sewage system.25
• Total electricity required to supply water (including pumping raw water, filtration/treatment,
and distribution) is 0.0021 kWh per gallon.26
• Total electricity required to treat wastewater is 0.0025 kWh per gallon,27 and only water
savings from indoor uses would have been treated.
Calculation 9: Electricity Savings From Not Supplying Saved Water to the Home
53,850 gallons of total water savings per year x 0.0021 =
113 kWh of electricity saved per year
Calculation 10: Electricity Savings From Not Treating Saved Wastewater from the Home
12,800 gallons of indoor water savings per year x 0.0025 =
32 kWh of electricity saved per year
Calculation 11: National Electricity Savings Potential
(718 kWh saved per home per year x 0.47 x 90,300 homes)
+ (113 kWh per home per year x 0.89 x 90,300 homes)
+ (32 kWh per home per year x 0.83 x 90,300 homes)
= 42.0 million kWh of electricity savings per year
22 Water used for irrigation would not have been treated at a wastewater treatment facility.
23 U.S. Census Bureau. American Housing Survey. 2019. 63,808,000 homes use natural gas to heat water, and
56,125,000 homes use electricity to heat water.
24 U.S. Census Bureau. American Housing Survey. 2019.
25 Ibid.
26 Electric Power Research Institute (EPRI), 2013. Electricity Use and Management in the Municipal Water Supply
and Wastewater Industries, EPRI, Palo Alto, California, November 2013 Report 3002001433.
27 Ibid.
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Calculation 12: National Natural Gas Savings Potential
(3.67 Mcf saved per home per year x 0.53 x 90,300 homes)
= 176,000 Mcf of natural gas savings per year
Cost Savings
National average water and wastewater costs for residential customers are $11.48 per 1,000
gallons.28 It is possible, although uncommon, that a homeowner could be billed separately for
these utility service connections and would therefore only incur the water supply costs for water
used for irrigation.
Based on the water savings presented above, EPA estimates that WaterSense labeled homes
could save between $350 and $885 annually in water supply and wastewater costs.
Factoring in potential energy savings, the average household with electric water heating may
save an additional $93 annually.29 The average household with natural gas water heating could
save an additional $38 annually.30
In total, a WaterSense labeled home could save between $388 and $978 annually on utility bills
compared to typical new construction.
28 WaterSense Estimate for 2019 based on Raftelis Financial Consulting. Water and Wastewater Rate Survey.
American Waterworks Association, 2016. WaterSense adjusted rate data using the Gross Domestic Product (GDP)
deflator for water from the U.S. Department of Commerce Bureau of Economic Analysis.
29 Based on a national residential average of $0.1301/kWh for 2019. U.S. Energy Information Administration. Short
Term Energy Outlook. Price Summary Table. Accessed December 1, 2020.
30 Based on a national residential average of $10.46/Mcf for 2019. U.S. Energy Information Administration. Short
Term Energy Outlook. Price Summary Table. Accessed December 1, 2020.
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