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A A i  ,    Q                              Water-Efficient Single-Family New Home Specification
   Water-Efficient Single-Family New Home Specification Supporting
I.      Introduction

The WaterSense® Program is developing criteria for water-efficient new homes. The intent of
the Water-Efficient Single-Family New Home Specification (Specification) is to reduce indoor
and outdoor water usage in new residential homes and encourage community infrastructure
savings. The Specification is applicable to newly constructed single-family homes and
townhomes, three stories or less in size.

II.     Current Status of Water Use in Residential New Homes

The environmental impact of the residential sector is significant. There are more than 120
million  homes in the United States and about 1.5 million new homes are constructed each year.
On average for all homes, 70 percent of household water is used indoors and 30 percent is
used outdoors; however, these percentages can easily flip during summer months in arid
climates. Outdoor water use, especially for irrigation, can strongly affect a municipality's peak
water use, upon which the sizing of water supply facilities is based. Table 1 presents the
average indoor water consumption data for an existing American home.1

                     Table 1. Typical Indoor Household Water Use

                                        Daily Use    Approximate % of
              Type  of Use       (gallons/person)     Total Indoor Use
              Toilets                         18.5                 26.7
              Clothes Washers                15.0                 21.7
              Showers                       11.6                 16.8
              Faucets                       10.9                 15.7
              Leaks                          9.5                 13.7
              Other                           1.6                  2.2
              Baths                           1.2                  1.7
              Dishwashers                    1.0                  1.4
                    Total                    69.3                100.0
Water use inside the home has been addressed nationally through two mechanisms. The
Energy Policy Act of 1992 (EPAct) established the maximum flush volume of toilets typically
installed in residential settings 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) at 80
pounds per square inch (psi) static pressure.  In 1998, the Department of Energy adopted a
maximum flow rate standard of 2.2 gpm at 60 psi for all faucets.2 However, new standards have
not been issued to mandate the more efficient plumbing products  being manufactured today.
1 AVWVA Research Foundation, 1998. Residential End Uses of Water.
2 63 Federal Register 13307; March 18, 1998.
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                                         Water-Efficient Single-Family New Home Specification
The water consumption of appliances found in homes is not currently specified in national
standards, but Congress approved future water use standards for dishwashers and clothes
washers in the Energy Independence and Security Act of 2007 that would take effect in 2010 for
dish washers and 2011 for clothes washers. The water use of clothes washers is addressed in
the ENERGY STAR® program.

Due in part to their environmental impact, some of today's home builders are building more
efficient homes under voluntary local, regional, and national green building programs. In 2005,
31 percent of builders reported that they were more than moderately involved with green
building. Market research suggests continued growth of the residential green building market as
more builders, suppliers, and product manufacturers become involved in green building and
more homeowners and homebuyers demand green homes. Some reports predict that green
home building may have recently reached its tipping point — the point where the builder
population turns from "less involved" to "more involved." In 2006, the growth in green home
building was expected  to rise by 20 percent over 2005, and in 2007, growth was  predicted to be
30 percent over 2006 numbers. If this holds true, more than two-thirds of builders will be
building green homes (at least 15 percent of their projects), with only one-third not yet engaged
in the marketplace.3

Every year builders are adopting more green principles in their construction of new homes. As
this trend continues and green homes become more mainstream, the way we define a green
home will also evolve. Although there is much debate within the industry as to what constitutes
a green home, the industry has begun to agree that green homes contain a number of common
elements, such as energy  efficiency, improved indoor air quality, water conservation,  resource
efficiency, and high performance construction processes.4  Reports indicate that  energy
efficiency is the top practice in  green home building.5 The use of water-efficient products and
practices, however, is often overlooked in the construction of  green homes and is not
considered a priority in many of the existing green building  programs being used today.

Recent studies indicate that it is feasible to build a home that  uses 20 percent less water than
other new homes. Specifically, Environments for Living's Summary Report "Water Efficiency
and Performance in Diamond Class Test Homes" states that "the technologies and equipment
to achieve overall water savings between 20 and 30 percent and maintain or improve overall
performance in new homes are readily available."

The WaterSense Labeled  New Homes program is an initiative designed to actively promote the
transformation of the mainstream home building industry towards increased water efficiency.
While there are already a number of green home building programs, the WaterSense
Specification provides national consistency in defining the features of a water-efficient new
home and enables builders anywhere in the country to obtain a WaterSense label on their
homes. The WaterSense Labeled New Homes program can be integrated into existing green
home building programs to reach a large number of home builders and facilitate its adoption as
a national specification. To maximize water efficiency, the WaterSense New Homes Program is
setting both indoor and outdoor water use criteria and requiring homeowner education to help
improve water-efficient behaviors.
 McGraw_Hill Construction. 2006. Residential Green Building SmartMarket Report.
4 Ibid.
5 Ibid.
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                                          Water-Efficient Single-Family New Home Specification
III.     WaterSense Water-Efficient Single-Family New Home Specification

The WaterSense Program developed this specification to address criteria for improvement and
recognition of water-efficient new homes. The Specification focuses specifically on new homes
to address water efficiency during the planning and design stages of home construction where
significant impacts can be achieved using readily available best technologies. Due to
differences in the design and construction of multi-dwelling units, this specification focuses on
single-family detached homes and town homes.

The Specification addresses both indoor and outdoor water use because water savings
achieved through indoor improvements can easily be lost through inefficient outdoor water use.
With respect to indoor water use, the Specification addresses plumbing fixtures in bathrooms,
hot water distribution systems, water-using appliances, and other water-using equipment. The
Specification addresses the static service pressure in the home to minimize unintentional water
wastage occurring from high water pressure within the  home. Kitchen and utility faucets are not
addressed since the different uses (e.g., pot filling) and user expectations (e.g., fill the pot
quickly) may not be adequately addressed with low-flow faucets. Water efficiency criteria for
showerheads also have not been addressed because research is still being conducted to
establish acceptable performance criteria for water-efficient showerheads. Outdoor water use is
addressed through landscape and  irrigation system design criteria. The Specification also
addresses homeowner education to inform the homeowner of the water-efficient components of
the home and encourage water-efficient behaviors.

Homes must meet the criteria in all areas to be considered for the WaterSense  label.  This
specification provides the minimum water efficiency criteria necessary to be considered a
WaterSense labeled home. Additional water conservation measures (e.g., gray water recycling)
can be included in the home provided they do not adversely impact the  criteria included in this
specification. This specification is not intended to contravene local codes and ordinances.

Third-party certification of homes seeking the WaterSense label will be  required. EPA is
currently developing the certification scheme for WaterSense labeled new homes.  This process
will be described in detail as part of the final specification for water-efficient single-family new

This specification will be revised as new products such as showerheads and/or weather-based
irrigation technologies are labeled under the WaterSense program. Revisions may also occur
when additional water-efficient building practices become acceptable and cost-effective to home
builders. Revisions to this specification  will not be retroactive and would be made following
discussions with building partners and other interested stakeholders. Adequate lead time will be
provided for builders to implement any changes.

Water Efficiency Criteria
There are three major types of water-efficiency criteria  included in this specification: indoor,
outdoor, and homeowner education. Each of these is described in detail below.
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                                         Water-Efficient Single-Family New Home Specification
Indoor Water Efficiency Criteria

   •  Service pressure - This specification establishes a maximum static service pressure of
      60 pounds per square inch (psi). Compliance with this measure shall be achieved by use
      of a pressure-regulating valve downstream of the water meter.  All fixture connections
      shall be downstream of the pressure regulator.

      Because flow rate is related to pressure, the maximum water flow from a fixture
      operating on a fixed setting can be reduced if the water pressure is reduced. For
      example,  a reduction in pressure from 100 psi to 50 psi at an outlet can result in water
      flow reduction of about one-third. Water pressure reductions can also save water by
      reducing the likelihood of leaking water pipes, leaking water heaters, dripping faucets,
      and catastrophic events when pipes, hoses, or component parts in a water-using product
      burst. A study in Denver, Colorado demonstrated an annual water savings of about 6
      percent for homes that received water service at lower pressures when compared to
      homes that received water services at higher pressures.

   •  Toilets - This specification requires that all toilets installed in the home be WaterSense
      labeled high efficiency toilets (HETs). These HETs have a maximum effective flush
      volume of 1.28 gallons per flush  and must effectively clear 350 grams of soy-based
      media. Information on these HETs is available at

   •  Bathroom faucets - This specification requires that all bathroom faucets installed in the
      home be WaterSense labeled bathroom faucets. The WaterSense specification sets the
      maximum flow rate of faucets and aerators at 1.5 gallons per minute (gpm) tested at a
      flowing pressure of 60 psi. The specification also includes a minimum flow rate of 0.8
      gpm tested at a flowing pressure of 20 psi to ensure performance across a variety of
      different household conditions. Information on these faucets is  available at
      http://www.epa.gov/watersense/specs/faucet final.htm.

   •  Showerheads - This specification does not establish a new maximum flow rate for
      individual showerheads; however it does establish a total allowable flow rate from all
      showerheads flowing at any given time at 2.5 gpm per  shower  compartment. This
      requirement also applies to rain systems, waterfalls, bodysprays, and jets. This
      specification defines a shower compartment as an area no larger than 2,500 square
      inches. An exception to this requirement is the use of recirculating showers.
      Recirculating showers are those designed to recirculate the water used in  a shower by
      capturing it in a basin and then pumping it through the shower  system. Most of these
      systems are designed to be switched on after initial  cleaning using a conventional
      showerhead and may include a filtering process.

      Market research suggests that up to four percent of new homes are being  constructed
      with multiple showerheads per shower compartment due in part to the ease of
      installation of these shower systems and consumer demand for upgraded  showers that
      allow for luxury shower experiences. These systems can use as much as 10 gpm of
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                                          Water-Efficient Single-Family New Home Specification
       water.6 Limiting showers designed for single individuals to one showerhead minimizes
       the amount of water used per shower.

       The Specification also requires that showers be equipped with automatic compensating
       valves that comply with ASSE 1016 for ASM EA112.18/CSA B125.1 and designed to
       provide thermal shock and scald protection at the flow rate of the showerhead that is

       Hot Water Delivery Systems - This specification establishes that all hot water pipes,
       both above and below ground, be insulated to a minimum of R4 and that each home be
       equipped with at least one of the following features: demand-initiated hot water
       recirculating system, whole house manifold system, and/or core plumbing system. These
       systems are to be designed to contain less than 0.38 gallons of water between the hot
       water source and any hot water fixture for whole house manifold and core plumbing
       systems and 0.13 gallons of water between the recirculating loop and any hot water
       fixture for demand-initiated water recirculating systems.

       The intent of requiring water efficient  hot water delivery systems is to reduce water
       waste by using technologies that provide hot water at the tap with a minimal wait time.
       An average American household wastes over 10,000 gallons of water each year while
       waiting for hot water to get to the fixture.7 Researchers believe that water waste can be
       reduced by 90 percent in new homes that are constructed with water-efficient hot water
       systems addressing plumbing design, pipe insulation, demand recirculation, and drain
       heat recovery.

       Insulating hot water piping reduces the amount of water wasted while waiting for hot
       water by keeping the water hotter and getting hot water to the point of use quicker.
       Insulating hot water piping also reduces energy losses as hot water moves through the
       lines to the point of use and when hot water sits in the lines between draws. Insulation
       can keep the water temperature 2°F to 4°F hotter compared to uninsulated pipes,
       allowing for a lower water heater temperature setting.

       Recirculating hot water delivery systems reduce water wasted while waiting for hot water
       by circulating the water in the pipes through the water heater until a specified
       temperature is reached. Demand-initiated recirculating systems save energy by not
       circulating hot water through the piping system continuously. Whole house manifold
       systems can use smaller diameter piping for some fixtures which allows hot water to
       arrive at fixtures faster, and less hot water is left standing in pipes after a draw, reducing
       both water and energy use. Core plumbing systems can reduce the total  amount of
       plumbing pipe installed;  the amount of conductive heat loss from the pipe; the amount of
       time it takes for hot water to reach baths, laundry areas, and the kitchen; and the amount
       of hot water left standing in pipes after a draw.

       Dishwashers - This specification establishes that dishwashers offered, financed,
       installed,  or sold as upgrades through the homebuilder shall be ENERGY STAR®
       labeled. ENERGY STAR qualified dishwashers use at least 41 percent less energy  than
 Biermayer, Peter. 2006. Potential Water and Energy Savings from Showerheads. Ernest Orlando Lawrence Berkley National
Laboratory. LBNL-58601 -Revised.
7 Home Builders Association of Metro Denver. 2007. Guide to the 2007 Built Green® Checklist.
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                                          Water-Efficient Single-Family New Home Specification
       the federal minimum standard for energy consumption and much less water than
       conventional models.

       Clothes Washers - This specification establishes that clothes washers offered, financed,
       installed, or sold as upgrades through the homebuilder shall be ENERGY STAR labeled
       and have a water factor (WF) of less than or equal to 6.0 gallons per cycle per cubic foot
       capacity. WF is the number of gallons used per cycle per cubic foot of clothes washer
       capacity. The lower the WF, the more water-efficient the clothes washer.

       Evaporative Air Conditioners - This specification establishes that evaporative air
       conditioners installed by the homebuilder shall use 5 gallons (or less) of water per ton-
       hour of cooling when adjusted to maximum water use.  Blow-down shall be based on
       time of operation, not to exceed 3 times in  one 24-hour operating period. The reservoir
       discharge outlet should be easily visible so the homeowner can see when the refill valve
       is leaking.

       Although evaporative air conditioners use about one-fourth the electricity of a
       conventional air conditioner, they add about 19,000 gallons, on average, to a
       homeowner's annual water consumption.8  Research indicates that some units appear to
       more efficiently evaporate water, thus, producing more cooling per unit of water used.

       Water Softeners - This specification establishes that water softeners installed by the
       homebuilder shall be certified to meet the NSF/ANSI 44 standard and have demand-
       initiated regeneration. If the water softener uses an ion exchange technology, it shall be
       capable of using potassium rather than sodium salt. Water softeners that use auto-
       initiated regeneration (fixed schedule) do not meet this specification.

       NSF/ANSI 44 standard is a third party certification that confirms the performance of the
       water softener. Demand-initiated systems measure water usage with a water meter and
       regenerate only when the meter counts down to zero. These systems do a better job of
       providing treated water than auto initiated systems because they regenerate  more
       closely to the time they need to and do  not waste water during unnecessary

       Potassium chloride is as effective as sodium chloride for water softening in both
       residential and commercial processes.  Plus, using potassium chloride has several
       benefits: it reduces the amount  of sodium in drinking water; the treated water contributes
       potassium to people's diets; and it eliminates the addition of sodium from water
       softeners into a household's septic system tank and drainfield. Potassium is an essential
       mineral for plants; whereas, sodium can damage plant tissues. Because sodium is
       replaced by potassium, this diluted wastewater is beneficial to a grass covered drain

       Drinking Water Treatment Systems - This  specification establishes that drinking water
       treatment systems installed by the homebuilder shall be certified to meet applicable
 National Association of Home Builders Research Center. Toolbase Services. Evaporative Coolers Whole-house Cooling in Arid
Regions at a Low First Cost.  http://www.toolbase.org/Technology-lnventory/HVAC/evaporative-coolers.

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                                          Water-Efficient Single-Family New Home Specification
       NSF/ANSI certifications and have an efficiency rate of not less than 85 percent. Systems
       using carbon filters can exceed efficiency ratings of 85 percent.

   •   Whole House Humidifiers - This specification does not address whole house humidifiers
       installed by the homebuilder. EPA is interested in  receiving any data relating to the
       water use and performance of furnace humidifiers.

Outdoor Water Efficiency Criteria

   •   Landscape Designs - This specification establishes that homebuilders shall landscape
       the entire yard so that either (1) the turf shall not exceed 40 percent of the landscapable
       area or (2) the evapotranspiration (ET) limit on the landscapable area shall be no more
       than 60 percent of the reference ET0 for cool season grass. The available precipitation
       for calculation purposes shall be no more than 25 percent of the average annual rainfall
       amount. The Specification also establishes that turf shall not be installed on slopes
       greater than 4:1.

       How and where turf is placed in the landscape can significantly reduce the amount of
       irrigation water needed to support the landscape. Lawns require a large amount of
       supplemental water and generally greater maintenance than other vegetation. Limiting
       turf to areas where it aesthetically highlights the house or where it has a practical
       function, such as in play areas, and grouping turf areas together can increase watering
       efficiency and significantly reduce evaporative and runoff losses.  Long,  narrow turf areas
       are difficult to water efficiently, and water tends to create excessive runoff on slopes
       greater than 4:1.

       The landscape water budget establishes the maximum amount of water to be applied
       through the irrigation system, based on climate, landscape size, irrigation efficiency, and
       plant needs. A properly designed water budget ensures that a landscape receives
       adequate irrigation without over-watering, saving water and the homeowner's time and
       money. Limiting available precipitation to no more than 25 percent in the water budget
       calculations better ensures that the landscape will  survive during seasons with less than
       average rainfall amounts.

   •   Mulching - This specification establishes that non-turf, non-hardscape areas shall
       include a 2 to 3-inch layer of mulching  materials. Mulches aid in greater retention of
       water by minimizing evaporation, reducing weed growth, moderating soil temperatures,
       and preventing erosion. Organic mulches also improve the condition of your soil as they
       decompose. Mulches are typically composed of wood bark chips, wood grindings, pine
       straws, nut shells, small gravel, or shredded landscape clippings.

   •   Pools/spas - This specification establishes that the water surface area of pools and/or
       spas installed by the homebuilder shall be considered in the landscape  design as part of
       the turf allowance and/or landscapable area used to calculated a water  budget. Under
       this  specification, pools are treated as turf to account for their annual evaporation rates
       and water use requirements.

   •   Ornamental Water Features - This specification establishes that builders shall not install
       or facilitate the installation of ornamental water features. Ornamental water features are

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                                       Water-Efficient Single-Family New Home Specification
   defined as fountains, ponds, waterfalls, man-made streams and other decorative water-
   related constructions provided solely for aesthetic or beautification purposes. Because
   these water features serve no functional or practical purpose their water use is not
   considered efficient.

•  Irrigation System Designs - This specification establishes that irrigation systems, if
   installed, shall, at a minimum, (1) be designed to sustain the landscape without creating
   flow or spray that leaves the property during a minimum continuous operating  duration
   specific for the type of irrigation system used; (2) be designed and installed by a
   WaterSense Irrigation Partner; (3) not use sprinkler heads to water plantings other than
   maintained turf grass; and (4) use microirrigation for planting beds and turf installed in
   strips of less than 8 feet wide.

   Good irrigation design and scheduling provides one of the greatest opportunities for
   water efficiency in the landscape. Irrigation design consists  of the layout of the sprinkler
   system, equipment selection  and sizing, filtration, pressure control, hydraulics  and
   layout. The goal of a good design and layout is to provide an irrigation system  with good
   overall distribution uniformity  to maintain plant health while conserving water resources.
   Lower uniformity  results in over-application of water to parts of the landscape in  order to
   apply enough water to those  areas that are under-irrigated.  Efficient systems should
   have no overspray across or  onto a street, driveway, or any other non-vegetated area
   that does not require irrigation. Microirrigation applies water at a low flow rate and low
   pressure to the roots of plants by depositing the water either on the soil surface or
   directly to the root zone. Microirrigation systems lose significantly less water to runoff
   and ET than  conventional systems because the water is applied to the roots and/or soil
   and soaks directly into the soil. These systems are good for slopes and small strips of
   turf which generally lose a lot of water to runoff and evaporation.

   WaterSense Irrigation Partners have a specified level of experience and/or training and
   have passed a comprehensive exam covering general irrigation subjects as well as
   specialty areas including water efficiency. These professionals have also agreed to
   follow a code of ethics. WaterSense Irrigation Partners evaluate site conditions and
   prepare professional irrigation plans to meet the needs of individual projects. This
   professional chooses the most effective irrigation equipment and design methods for the
   site and individual project requirements, ensuring that the best system is used for a
   particular site.

•  Irrigation Controllers - This specification establishes that irrigation controllers shall have
   multiple programming capabilities, multiple start times, variable run times, variable
   scheduling, a percent adjust (water  budget) feature, the capability to accept external  soil
   moisture and/or rain sensors, non-volatile memory or self-charging battery circuit, and
   complete shut off capability for the total cessation of outdoor irrigation. Irrigation
   controllers are one of the most important components of an irrigation system because
   they determine when and where the water goes in the landscape. The more
   programming flexibility the controller has, the more efficiently water can be applied to the
   landscape. The current controller requirements are based on draft recommendations
   from irrigation professionals.  EPA plans to conduct additional  research on the  criteria for
   controllers before releasing a final specification for water-efficient new homes.
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                                          Water-Efficient Single-Family New Home Specification
   •   Sprinkler Heads - This specification establishes that sprinkler heads shall have a 4 inch
       or greater pop-up height and matched precipitation nozzles. It is important for the pop-up
       height to be greater than the grass height to prevent the sprinkler heads from being
       blocked by the grass, thereby reducing the distribution uniformity.

   •   Mircroirrigation Systems - This specification establishes that microirrigation systems
       shall be equipped with pressure regulators, filters, and flush end assemblies. Pressure
       regulators control the pressure of the water in the system and prevent more water being
       applied than necessary. Filters remove sand and larger suspended particles before they
       enter the distribution network and flush end assemblies allow the systems to be
       maintained properly by flushing out particles that accumulate in microirrigation pipelines
       before they build-up to sizes and amounts that cause plugging problems.

   •   Schedules - This specification establishes that two seasonal water schedules be posted
       at the controller. One schedule shall be designed to address the initial grow-in phase of
       the landscape and the second schedule shall be designed to address an established
       landscape. Regularly changing the irrigation schedule is an important component of a
       water-efficient landscape.

Homeowner Education

This specification establishes that the builder shall develop and provide to the homebuyer a
written operating and maintenance manual for all water-using equipment or controls installed in
the house or yard. If clothes washers or dishwashers are not provided, information about water-
efficient appliances shall also be included. The intent of the manual is  to educate homeowners
on the efficient use of water and the benefits of doing so, as well as how to operate and
maintain their home to achieve  the highest level of performance.
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                                           Water-Efficient Single-Family New Home Specification
Potential Water and Energy Savings

Water Savings

The average indoor household water usage for homes constructed after 1994 with toilets,
faucets, and showerheads that comply with EPAct standards is estimated to be approximately
50 gallons per person per day (see Table 2). Expected water usage for homes constructed to be
water-efficient is difficult to estimate as limited data are available. Data from six studies are

    •   High efficiency homes being offered by Durham Region in Canada, in conjunction with
       Tribute Communities, Natural Resources Canada, and the Federation of Canadian
       Municipalities demonstrated a water savings of 22.3 percent during a six month period
       (October 2006 - March 2007) over standard homes constructed at the same time in the
       same development. The 91 upgraded homes were constructed with ENERGY STAR
       water-efficient front-loading clothes washers,  ENERGY STAR dishwashers, HETs, and
       efficient showerheads.9

    •   The Masco Contractor Services Environments for Living® program conducted a detailed
       study of water efficiency in three new homes in 2004 to 2005. The homes were
       constructed with low-flow faucets and showerheads, high performing toilets, ENERGY
       STAR dishwashers, top performing clothes washers, electronic-demand hot water
       distribution systems, weather-based irrigation controllers, and a water-efficient
       landscape. The study encountered problems getting data after the houses were bought
       but one of the homes demonstrated an indoor water savings of 34 percent.10

•      A series of three intervention studies were conducted  from 1999 to 2003 to collect data
       on water conserving fixtures and appliances. Seattle Public Utilities conducted the first
       study on 37 single-family homes in 1999 to 2000, East Bay Municipal Utility District
       (EBMUD) conducted the second study on 33  homes in 2001 to 2003, and Tampa Water
       conducted the third study on 26 homes in 2003. All homes included in the studies were
       retrofitted with high efficiency clothes washers, showerheads, toilets, and faucets. Water
       usage data after the  retrofits demonstrated a water savings of 37.2 percent in Seattle, 39
       percent in EBMUD, and 49.7 percent in Tampa.11'12'13

    •   Water-efficient homes labeled under Southern Nevada Water Authority's Water Smart
       Home program are expected to save 75,000 gallons of water per year per home over
       homes built a decade ago. These homes are constructed with water-smart landscaping
       in the front yard, high-efficiency dishwashers, faucets, and showerheads.14
 Veritec Consulting, Inc. 2007. Region of Durham Efficiency Community, Interim Report. May 4.
  Environments for Living. Summary Report: Water Efficiency and Performance in Diamond Classiest Homes. September 2005.
  Mayer, P., DeOreo, W., et al. 2000. Seattle Home Water Conservation Study: The Impacts of High Efficiency Plumbing Fixture
Retrofits in Single-Family Homes. Aquacraft, Inc. Water Engineering and Management. December.
  Mayer, P., DeOreo, W., et al. 2003. Residential Indoor Water Conservation Study: Evaluation of High Efficiency Indoor Plumbing
Fixture Retrofits in Single-Family Homes in the East Bay Municipal Utility District Service Area. Aquacraft, Inc. Water Engineering
and Management. July.
  Mayer, P., DeOreo, W., et al. 2004. Tampa Water Department Residential Water Conservation Study: The Impacts of High
Efficiency Plumbing Fixture Retrofits in Single-Family Homes. Aquacraft, Inc. Water Engineering and Management. January.
 Southern Nevada Water Authority Web site http://www.snwa.com/html/cons_wshome_features.html.

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                                           Water-Efficient Single-Family New Home Specification
To estimate the potential indoor water savings of water-efficient single-family homes,
WaterSense developed an expected water use associated with the required features of the
home and then compared those usage estimates to standard water usage for those features to
derive savings per feature. Savings for all of the features in the new home specification were
added to estimate the total water savings. As shown in Table 2, WaterSense expects a water-
efficient home to use 21 percent less water indoors than a standard home.

Assuming that the average indoor household water usage for homes constructed to current
standards is 130 gallons/day (gpd), the water savings from the indoor  requirements can result in
an annual savings of approximately 10,000 gallons per home (see Calculation 1).

                      Calculation 1. Average Household Water Savings
  50 gpd/person • 2.6 people/household • 0.21 water savings = 27.3 gpd savings • 365 days/yr
                                = 9,965 gal  saved/yr/house

Extrapolated to the national level, potential estimated water savings from the indoor
components of the home could be as great as 15 billion gallons annually (see Calculation 2).
These estimates clearly demonstrate the significant water saving potential of building water-
efficient new single family homes.

                       Calculation 2. National Water Savings Potential
  9,965 gal/yr/house •  1,465,400 annual housing starts for single family homes15 = 14.6 billion
                               gallons water saved per year

WaterSense also expects significant outdoor water savings for homes installing a water-efficient
landscape and irrigation system, if applicable.  However, there are little data on the "standard"
landscape and "standard" outdoor water usage for single family homes. Data indicate that the
national average for residential irrigation ranges from 25 to 29 gallons  per person day.16

WaterSense estimates that a reduction of turf from about 80 percent in a standard yard to 40
percent in a water-efficient landscape results in a water savings of approximately 25 percent.17
In addition, WaterSense estimates that an efficient irrigation system with appropriate scheduling
can result in a water savings  of 25  percent over non-efficient irrigation systems.18 WaterSense
has not tried to estimate potential household or national savings associated with the outdoor
criteria due to the variability associated with outdoor water usage across the country.

Energy Savings

WaterSense expects water-efficient single family homes to save approximately 3,500 gallons of
hot water per year (see Table 3 and Calculation 3). This expected hot  water savings results in
618 kilowatts (kWh) of electricity or 3,070 cubic feet of natural gas savings each year (see
Calculations 4 and 5).
  NAHB. 2007. Housing Facts, Figures and Trends, p. 3 - 2006 Annual Housing Starts for Single-Family. May.
  Vickers, A. 2002. Handbook of Water Use and Conservation. Plow Press.
  WaterSense analysis based on evaluation of watering requirements of landscapes with 80 percent turf and 20 percent bushes
and trees compared to landscapes with 40 percent turf and 60 percent bushes and trees in various locations in the country.
  Gleick, P., Haasz, D., et al. 2003. Waste Not, Want Not: The Potential for Urban Water Conservation in California,  p 70. Pacific
Institute for Studies in Development, Environment, and Security. November.

                                                11                                May 14, 2008

                                           Water-Efficient Single-Family New Home Specification
In addition to the energy savings from the home itself, WaterSense estimates that an additional
33 kWh of electricity is saved by not supplying and treating the 9,965 gallons of water saved per
home (see Calculation 6). National energy savings could exceed 403 million kWh of electricity
and 2.5 billion cubic feet (Bcf) of natural gas each year (see Calculations 7 and 8).

                    Calculation 3. Average Household Hot Water Savings
             9.6 gpd hot water saved • 365 days/yr = 3,504 gal hot water saved/yr

           Calculation 4. Electricity Savings Per Household from Hot Water Savings
          3,504gal/year • 176.5 kWh of electricity/1,000 gal = 618 kWh of electricity/yr

          Calculation 5. Natural Gas Savings Per Household from Hot Water Savings
3,504 gal/yr •  0.8768 thousand cubic feet (Mcf) of natural gas/1,000 gal = 3.07 Mcf (3,070 cubic
                                   feet) of natural gas/yr

        Calculation 6. Electricity Savings From Not Supplying Saved Water to the House
         9,965 gal/yr • 0.0033 kWh of electricity/gal = 32.88 kWh of electricity/yr saved

                      Calculation 7. National Electricity Savings Potential
    (618 kWh/yr/home • 0.40 • 1,465,400) + (32.88 kWh/yr/home • 0.85 • 1,465,400 homes)
                              = 403 million kWh of electricity/yr

                    Calculation 8.  National Natural Gas Savings Potential
                         3.07 Mcf/yr/home • 1,465,400 homes • 0.56
                 = 2.5 million Mcf of natural gas/yr = 2.5 Bcf of natural gas/yr

These calculations are based upon  the following assumptions:
   •   Approximately 70 percent of faucet water used in a  household is hot water,19100
       percent of dishwasher water is hot water, and 28 percent of water used for clothes
       washing is hot water.20
   •   Approximately 40 percent of occupied residences in the United States heat their water
       using electricity and 56 percent heat their water using  natural gas.21
   •   Approximately 85 percent of households in the United States are connected to a water
       supply system.22
   •   Total electricity required to supply and dispose of each gallon of water delivered to a
       house  is 0.0033 kWh. Surface water supply requires 0.0015 KWh of electricity per gallon
       of water delivered (includes  pumping raw water, filtration/treatment, and distribution) and
       wastewater treatment requires 0.0018 KWh of electricity per gallon of water treated
       (average across various treatment types and plant sizes).23
   •   Water  heating consumes 0.2 kWh of electricity per gallon of water heated (see
       Calculation 9), assuming:
  Mayer, P., DeOreo, W., et al. 2004.
20 Mayer, P., DeOreo, W., et al. 2000.
  U.S. Department of Housing and Urban Development and U.S. Census Bureau. American Housing Survey for the United States
2005. Table 1A-4, page 6.
  Hudson, Susan S. et al. Estimated Use of Water in the United States in 2000. U.S. Geological Survey Circular 1268. Department
of the Interior. Table 5. page 14.
  Goldstein, R. & W. Smith. 2002. Water & Sustainability Volume 4: U.S. Electricity Consumption for Water Treatment & Supply -
the Next Half Century. Electric Power Research Institute, March 2002.

                                                12                                May 14, 2008

                                      Water-Efficient Single-Family New Home Specification
       o  Specific heat of water = 1.0 BTU/lb •  °F
       o  1 gallon of water = 8.34 Ibs
       o  1 kWh = 3,412 BTUs
       o  Incoming water temperature is raised from 55°F to 120°F (A 65°F)
       o  Water heating process is 90 percent efficient, electric hot water heater

                                  Calculation 9.
           [(1 gal • 1.0 BTU/lbs • °F) (1 KWh/3,412 BTUs)/(1 gal/8.34 Ibs) • 65°F] 70.90
                                     = 0.1765kWh/gal

•  Water heating consumes 0.8768 Mcf of natural gas per 1,000 gallons of water heated
   (See Calculations 10 and 11) assuming:
       o  Specific heat of water = 1.0 BTU/lb •  °F
       o  1 gallon of water = 8.34 Ibs
       o  1 Therm = 99,976 BTUs
       o  Incoming water temperature is raised from 55°F to 120°F (A 65°F)
       o  Water heating process is 60 percent efficient, natural gas hot water heater

                                 Calculation 10.
        [(1 gal •  1.0 BTU/lbs •  °F) (1 Therm/99,976 BTUs)/(1 gallon/8.34 Ibs) • 65°F] /0.60
                                  = 0.009037 Therms/gal

                                 Calculation 11.
            0.009037 Therms/gal • 1,000 gal • 1 Mcf/10.307 Therms = 0.8768 Mcf/kgal
                                          13                              May 14, 2008

                                                                                             Water-Efficient Single-Family New Home Specification
Table 2. Expected Daily Per Capita Indoor Water Savings from WaterSense Labeled New Homes
Hot water
              Standard Water Use

             2.2 gpm

             2.5 gpm
             ~10 gallons per day per
             household wasted 8
Dishwashers    8.6 gallons per load
                (6 gallons per cycle)
Clothes         39.6 gallons per load
washers        (12 gallons per cycle
                per cubic foot)
Total Indoor

 Standard Use



                 WaterSense Criteria
               1.5 gpm
2.5 gpm
Assume 10% water
savings for insulation
and between 15 - 20%
water savings for
improved design.3
5.8 gallons per load
(4 gallons per cycled
24 gallons per load
(6 gallons per cycle per
cubic foot)
 Expected Use



  Expected Water
     1.63 (20%)
     0.57 (5%)

      0 (0%)
     0.96 (25%)

     0.35 (33%)

     6.91 (45%)

10.42 (21% savings)




Assumes 5.1 flushes/day/person per Mayer. P, DeOreo, W. et al 2000 and 2003.
Assumes flow of 1.2 gpm and average use of 9.34 minutes/person/day per Mayer, P., DeOreo, W. et al 2000 and 2003.
Assumes flow of 0.97 gpm and average use of 10.97 minutes/person/day per Mayer, P., DeOreo, W. et al 2000 and 2003.
Assumes flow of 2.13 gpm, average use of 8.36 min/shower/person, and 0.58 showers/person/day per Mayer P., DeOreo W. et al 2000 and 2003.
Klein, Gary. Hot Water Distribution Considerations for BMPs. Presentation made on August 21, 2006 to the California Urban Water Conservation Council.
Assumes 2.6 persons per household per U.S. Department of Housing and Urban Development 2005 .
Acker, L, Klein, G. Benefits of Demand-Controlled Pumping. Home Energy. September/October 2006.
Assumes 8.64 gallons/load and 0.12 loads/person per Mayer, P., DeOreo, W. et al 2000, 2003, and 2004.
ENERGY STAR Frequently Asked Questions on Dishwashers. accessed 2/15/08.
Assumes 39.36 gallons/load and 0.39 loads/person per Mayer, P., DeOreo, W. et al 2000, 2003, and 2004.
Assumes 24.15 gallons/load and 0.35 loads/person per Mayer, P., DeOreo, W. et al 2000, 2003, and 2004.
                                                                                                                                    May 14, 2008

                                                                                 Water-Efficient Single-Family New Home Specification
 Table 3. Expected Hot Water Savings from WaterSense Labeled New Homes
        Indoor Feature
Bathroom faucets
Hot water delivery systems
Clothes washers
Expected Water Savings
        0.9 gpd
       17.9 gpd
        23 gpd
Percent Hot Water
Expected Hot Water Savings
          1.2 gpd
          2.5 gpd
          0.9 gpd
          5.0 gpd
          9.6 gpd
                                                                                                                   May 14, 2008

                                               Water-Efficient Single-Family New Home Specification
Cost Effectiveness and Payback Period

WaterSense estimates that the incremental costs associated with the criteria of this specification
will range from $800 to $3,000 (see Table 3). This analysis is based on the potential incremental
costs associated with  building a WaterSense labeled new home versus a new home
constructed to comply with basic requirements and practices.36

Table 3.  Estimate of  Incremental Costs Associated with the Specification
             WaterSense Criteria
Service pressure - pressure regulating valve
WaterSense labeled HETs
WaterSense labeled faucets
Efficient hot water delivery systems
ENERGY STAR dishwashers (if installed)
ENERGY STAR clothes washers (if installed)
Turf and  mulching
3rd party certification of home
                                                            Incremental Cost Estimate
                                                                $0 (core plumbing)40
                                                                 -$200 (manifold)41
                                                          $2,000 (recirculating system)42
                                                                  $800 to $3,000
The average homeowner of a WaterSense labeled new home will realize $60.60 savings on
water and wastewater costs annually due to lower indoor water consumption (see Calculation

                  Calculation 12. Annual Water and Wastewater Cost Savings
                            10,000 gallons/yr • $6.06/1,000 gallons47 = $60.60/yr
Factoring in the accompanying energy savings, the average household with electric water
heating may save an additional $58.71 (618 kWh/yr • $.095/kWh  ), for a combined annual

   Assumes home has 2.5 bathrooms, 1 kitchen, 0.36 acre lot (15,682 ft2); and total landscapable area of 12,280 ft2.
   Price based upon retail list prices of products found on various retailer Web sites. The range assumes some houses are already
constructed with the valves in place.
   Price range based upon retail list prices of products found on various retailer Web sites.
  Assumes the cost of a WaterSense labeled aerator is $4 and a standard 2.2 gpm aerator is $1.
   Assumes the incremental cost would negligible due to reduced piping costs.
   Assumes a baseline hot water delivery systems is trunk and branch with copper piping with materials and labor $1,100. Assume
manifold system with PEX with materials and labor is $920. Source: NAHB Research Center PATH Field Evaluation. Evaluation of
Residential Water Distribution Piping Installation: Time, Cost, & Performance Comparison PEX & Copper. September 2006.
   Assume increased cost of $1,000 to $2,000 due to increased piping requirements (up to 1 /3 more piping required), pump costs,
and additional labor for the installation of the additional electrical components. Source: Telephone conversations with the Plumbing
Manufacturers Institute.
   Price based upon retail list prices of products found on various retailers' Web sites.
   Price based upon retail list prices of products found on various retailers' Web sites.
45                        9                             9
   Assume a unit cost of $1.50/ft for a traditional landscape and $1.55/ft for a water-efficient landscape based on limited data on
Xeriscape landscaping. These costs may vary greatly across different parts of the country.
   Telephone conversation with the Residential Energy Services Network (RESNET).
   Raftelis Financial Consulting. Water and Wastewater Rate Survey. American Water Works Association. 2006.
   Average Retail Price of Electricity to Ultimate Consumers by End-Use Sector, Energy Information Administration.
                                                                                        May 14, 2008

                                         Water-Efficient Single-Family New Home Specification
savings of approximately $119.31. The average household with natural gas water heating may
save an additional $42.49 (3.07 Mcf/yr • $13.84/Mcf49), for a combined annual savings of
approximately $103.

The average payback period for an average WaterSense labeled home would range between 6
and 25 years  for those with electric water heating and 7 to 29 years for those heating with
natural gas (see Calculations 13 and 14). These payback periods will improve if outdoor water
use savings are also realized.

              Calculation 13. Average Payback Period (Electric Water Heating)
                   $800 incremental cost for home/$120 cost savings/yr = 6.7 years
                  $3,000 incremental cost for home/$120 cost savings/yr = 25 years

            Calculation 14. Average Payback Period (Natural Gas Water Heating)
                   $800 incremental cost for home/$103 cost savings/yr = 7.8 years
                  $3,000 incremental cost for home/$103 cost savings/yr = 29 years
IV.     Request for Comments and Data

At this time WaterSense is interested in receiving comments on
   •   Any and all aspects of the proposed Specification;
   •   The performance and water savings of water-efficient homes; and
   •   The use of best management practices to manage stormwater runoff from single-family
       homes. The objective of stormwater management is to maintain the quality and quantity
       of stormwater runoff to pre-development levels using structural or non-structural devices
       to temporarily store or treat stormwater runoff.
  Short-Term Energy Outlook, Energy Information Administration.