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HERS H2O and WaterSense 2.0

Collage of a kitchen faucet, water heater, and outdoor sprinkler system. All are considered when rating a home's water efficiency.

HERS H2O: A National Program for Rating the Water Efficiency of New Homes


What is WaterSense?

The US EPA launched the WaterSense Homes program in 2009. The goal of the program is to encourage the construction and purchase of water-efficient, high-performing homes that reduce indoor and outdoor water use and encourage community infrastructure savings.

WaterSense Version 1 was in effect from 2009 through 2021. Version 2 was officially released in February 2021 and is undergoing a phase-in implementation period. Homes permitted between February – June 2021 may use either version of WaterSense while homes permitted after July 1, 2021 must use WaterSense v2.

WaterSense for Homes v2 brings about some significant updates to the program. The new version brings about a wholesale change to the methodology in the technical and certification requirements. It now requires that homes meet a minimum set of quality performance criteria and achieve 30% water efficiency over typical new construction. This structure reduces the prescriptive requirements 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.

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.

To confirm that homes meet this efficiency threshold, EPA will require the homes to be certified by an approved Home Certification Organization (HCO) using a WaterSense approved certification method.


RESNET HERS H2O logoRESNET is a WaterSense HCO and the HERSH2O certification program is an approved certification method for WaterSense. HERSH2O builds off RESNET’s nationally recognized HERS Index, which is the gold standard for rating the energy efficiency of a home. HERSH2O is a system for rating whole-house water efficiency that includes both indoor and outdoor uses. A HERSH2O rating is determined by comparing the home that is being rated with a reference home that is representative of construction practices (plumbing products and practices) circa 2006.

The basis for HERSH2O is the ANSI/RESNET/ICC Standard 850-2020. Water efficiency ratings conducted after March 1, 2020 and submitted to RESNET will be recognized as confirmed HERSH2O ratings. It is important to note that HERSH2O ratings are currently only applicable for one- and two- family dwellings.

How the programs work together

Homes permitted after February 1, 2020 may use the HERSH2O certification program to qualify for WaterSense Homes v2.0. The Rater shall confirm that a home meets the mandatory requirements of the WaterSense Specification for Homes, Version 2.0 and that the home meets the HERSH2O Index target score of 70 or less. The Rater shall document the certification decision and provide to the builder partner the WaterSense label certificate for each certified home. When the WaterSense label is issued, the Rater shall also supply the builder partner with guidelines on proper use of the WaterSense program marks.

Prior to issuing the WaterSense v2.0 label, the HERSH2O rater shall ensure that a builder partnership agreement is in place between the Environmental Protection Agency WaterSense Program and the builder. To verify the partnership, the Rater should check the WaterSense website for a current list of builder partners. If the builder is not listed on the WaterSense website, the partnership can be verified by contacting the WaterSense Helpline at (866) WTRSENS (987-7367) or


Becoming a HERSH2O Rater or Rating Field Inspector

A man wearing a hardhat inspects a newly constructed home.
RESNET requires two mandatory online training courses to be certified with HERSH2O and WaterSense 2.0. The links to these are here:
HERS H20 Rater Training
Verifier Training for WaterSense Labeled Homes Program, Version 2.0 

All active certified RESNET Home Energy Raters and Rating Field Inspectors are eligible to conduct HERSH2O ratings after completing the online training program and meeting the following criteria:

  • Work under the auspices of a RESNET accredited HERSH2O QA Provider.
  • Become familiar with the HERSH2O Inspection Checklist and Inspection Guidance document as well as the calculation spreadsheet.
  • Complete three probationary test ratings. The test ratings should be conducted on a site visit to a completed new home or an existing home and must use the HERSH2O Inspection Checklist, Inspection Guidance Document, and Calculation Spreadsheet.
  • HERSH2O Rating Field Inspectors shall work under the direct supervision of a certified HERSH2O Rater and shall only be responsible for conducting field verification of HERSH2O components.
  • HERSH2O Raters shall submit the completed Excel workbook, which includes the calculation spreadsheet, inspection checklist, and project information to their QA Provider for upload to RESNET.
  • HERSH2O Raters and Rating Field Inspectors shall comply with the RESNET Code of Ethics.

Building Efficiency Resources (BER) is an approved HERSH2O Provider and is ready to assist you with your HERSH2O and WaterSense certification requirements! Simply email us at to get started today! Additionally, if you are a HERSH2O Rater and need a copy of the HERSH2O Excel workbook, please contact us to get a copy.