Water Ratings Identify Homes that Conserve Every Drop
Last Updated: Mar 20, 2025No matter where you live, water is becoming a precious—and more costly—resource. The price many homeowners pay for clean, potable water has increased significantly in the last decade, even in areas untouched by drought. Much of that cost is attributable to long-neglected infrastructure repairs, but there's an additional concern in arid locales: availability. In these places, insufficient water resources can make the difference between building a new home and not building one.
Until recently, residential water conservation has focused on limiting usage by plumbing fixtures such as bathroom faucets, showerheads, and toilets. Since 2006 the US Environmental Protection Agency's WaterSense label has identified plumbing products that save at least 20 percent more water than others.
But a more practical approach assesses all the water use in a home. This is what water rating programs do, just as energy-efficiency ratings score homes on all the energy they consume.
"It's exciting to see these emerging water ratings take on a similar evolution to what we've seen for energy efficiency," says Cindy Wasser, senior manager of green building programs for Home Innovation Research Labs. "We have more tools now to look at water with a whole-home approach," Wasser says. Advances in computer modeling help make this possible.
Wasser's organization participates in certifying homes under two water-conservation programs: the National Green Building Standard's Water Rating Index and the EPA's WaterSense Home. Many programs use similar criteria to measure homes' water use, and some work in tangent with others. But they also differ in the types of water use they measure and how they do it.
Table of Contents
- What Are The Benefits of Water Rating Programs?
- What Home Water-Rating Programs Exist?
- What is the Water Efficiency Rating Score (WERS)?
- What is the Water Rating Index (WRI?)
- What is NGBS Green+ Zero Water Badge?
- What is WaterSense Home?
- What is HERS H20?
- What is Florida Water Star?
- How Much Does it Cost to Have a Home Water Rated?
- Can a Water Rating Program Help My Existing Home Save Water?
What Are The Benefits of Water Rating Programs?
Buying a house with a water-rating certification ensures your home is more water-efficient than most. This trait can lessen the impact of rising water prices on your budget, something that's particularly advantageous in communities where the per-gallon cost of water increases with use. A certification can also help you estimate future costs by predicting water usage. Some programs include inspections that ensure your home's plumbing is free of leaks and pressure issues that can become headaches later.
Certification programs that rate a home's water efficiency on a shared numeric scale, which many do, enable homeowners to compare different houses' water usage before they buy. "Up to this point, you could see the flow-rate stamp on a faucet or the label on your toilet tank, but it wasn't something significant to homeowners," says Wasser. With the rating systems, she says, "Homeowners get the benefit of an easy-to-understand number showing how efficient their home is, compared to others."
For builders in drought-impacted areas, certification can mean the difference between building or not building. When the water demand exceeds available resources – what Santa Fe sustainability consultant Kim Shanahan refers to as the "sustainability failure point" – communities will have no choice but to shut down new construction. "When that occurs, local jurisdictions will legitimately say the game is over for homebuilders," Shanahan says. Where there is adequate water, certification can enable builders to construct more houses or benefit from reduced connection fees or rebates from local water authorities.
Large, publicly traded builders also face increasing pressure from investors to embrace sustainability and lessen their environmental impact. What's more, homes certified to use less water appeal to many new homebuyers. Rating systems offer builders a platform to market their homes to these water-conscious customers.
What Home Water-Rating Programs Exist?
- Water Efficiency Rating Score (WERS)
- Water Rating Index (WRI)
- NGBS Green + Zero Water
- WaterSense Home
- HERSH20
- Florida Water Star
What is the Water Efficiency Rating Score (WERS)?
In 2013, in suffering under a decades-long drought, the City of Santa Fe turned to its local homebuilders' association for ideas on curbing residential water usage. Partnering in turn with the Green Builder Coalition, they devised the Water Efficiency Rating Score (WERS), a predictive analysis of a home's water use based on a 100-point scale. Modeled after the 100-point Home Energy Rating Score (HERS) developed by the Residential Energy Services Network (RESNET), WERS offered builders a familiar metric to represent water use. Like HERS, a WERS score of 100 equals the water use of an average home built to code in 2006. The lower the score, the more water-efficient the house is.
In 2016, Santa Fe made a pre-construction WERS score of 70 mandatory new single-family houses. As a result, all homes built there since are certified, according to Shanahan, involved with the program's development. The requirement is expected to extend to multifamily homes later this year.
The WERS rating calculates water use both indoors and out. It assesses the efficiency of hot-water delivery as well as flow rates of plumbing fixtures and appliances. In addition, it pays considerable attention to water usage outside the home, taking into account irrigation systems, fountains, pools, spas, landscape design, and the moisture requirements of plants. It also figures into its calculations reuse through the collection of rainwater, greywater, and blackwater.\
WERS provides both a final score and the number of gallons a home can expect to use. This score gives builders a tool to negotiate with local water districts and offers homeowners an estimate of what they may pay for water. Its performance-based flexibility "allows for the inherent tradeoff possibilities that builders like," says Shanahan, opening the door to innovative technologies.
The WERS system has been or is being considered for use as a compliance path for local codes, incentive programs, and green-building certifications in several places, including Austin, Santa Barbara, and Vermont. It is also currently being integrated into Built Green Canada's BUILT GREEN home certification.
What is NGBS Green+ Zero Water Badge?
Also administered by Home Innovation Research Labs, NGBS Green+ Certification identifies new homes that meet the highest performance standards in one or more of six categories. In addition to Zero Water, these include Net Zero Energy, Resilience, Smart Home, Universal Design, and Wellness. It is only available for new homes.
An NGBS Green+ Zero Water home can meet all its water needs through rainwater capture or reuse of sources such as greywater or blackwater. While certified homes may connect to a public water supply, the goal is for these homes to provide their own water. Therefore, on the WRI scale, NGBS Green+ Zero Water Homes score a "0."
Homes meeting the "Green+ Zero" standard are equipped with the most water-efficient fixtures, landscape, and plumbing systems, as well as storage tanks and collection and treatment systems required to harvest and safely use water from these sources. Like WRI, the NGBS Green+ badge is pursued alongside NGBS Green Certification.
Because HERS H20 calculations utilize American National Standards Institute (ANSI) standards, it does not account for rainwater collection or greywater, for which ANSI has not established benchmarks. For now, HERS H20 is limited to single-family homes and duplexes but will include multifamily homes when it's revised in 2023, Meres said.
Approximately 500 homes were rated under a pilot program that launched in October 2020. Meres expects the program to certify 3,000 to 5,000 more homes this year and eventually 55,000 to 75,000 homes annually, equal to about a quarter of the homes that gain HERS energy certification. While the rating can apply to existing homes, 98 percent of HERS-rated homes are new construction, a pattern Meres expects HERS H20 to mirror.
How Much Does it Cost to Have a Home Water Rated?
The administrative costs of most water use programs are covered by fees paid for the green building programs of which they are a part. For example, administrative fees for the National Green Building Standard, of which WRI is a part, range from $100 for a single-family home to more than $300 for a multifamily project. A verifier or rater required to confirm the home meets the standard could cost the builder an additional $400 to $1,000.
It's estimated that homes built to third-party green certifications can cost 1 percent to 5 percent more to build. But builders can add water efficiency with little incremental cost. Because most rating systems are based on performance goals rather than specific features, builders have flexibility in how they reach certification goals.
Still, many other elements called for in these programs, like low-flow fixtures and native plantings, can help save water in any house, regardless of its age. For example, fixing common leaks alone can save about 10 percent on your water bill, according to the EPA. A water rating is a valuable tool for new-home owners to spell out future water usage in black and white. For owners of older homes, they can serve as a guide to some steps you can take to move in the right direction.
