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Public Water Supply Tools, Resources & Performance Standards

Resources from the MassDEP Water Management Act Program for use by Public Water Suppliers


Firm Yield Estimator

The Firm Yield of a reservoir is the simulated maximum annual average rate of withdrawal that can be sustained every day during a drought. The U.S. Geologic Survey developed the Firm Yield Estimator, a Microsoft Access database which can be downloaded for use in simulating the Firm Yield of a reservoir. The USGS study included the simulated Firm Yield of 38 reservoirs or reservoir systems in 27 Massachusetts cities and towns. Reservoirs not included in the USGS study can be added. Contact MassDEP for assistance in collecting and inputting the necessary data required to simulate the firm yield of reservoirs not included in the USGS study.

The results of the USGS study are summarized in the USGS report “Refinement and Evaluation of the Massachusetts Firm-Yield Estimator Version 2.0”. The report, downloadable software and user’s manual is available at

EPA Asset Management and Debt Capacity Tool

Water Management Act (WMA) permit applicants may request a cost feasibility assessment in conjunction with their mitigation plan. The purpose of the assessment is to assist MassDEP in determining if the applicant has proposed a mitigation plan that will both meet the conditions of their WMA permit and is feasible for the applicant to finance over the term of their permit. This Excel-based tool, intended to help wastewater and drinking water utilities develop an asset management plan and plan for long-term financial health, my be used by applicants to submit their 10-year budget.


American Water Works Association M36 Water Audit Training Document

This document supplements the AWWA M36 manual and software, and can be used to help you complete a Level 1 M36 Audit. July 2017.

SWIMI Technical Resources

The SWMI Technical Resources webpage contains data generated during the SWMI process, including an on-line interactive GIS map. The webpage also contains Access databases, Excel files, GIS files and statewide SWMI maps for downloading, as well as links to relevant U.S. Geological Survey reports.

Water Management Act Grant Programs for Public Water Suppliers

This grant program is designed to assist eligible public water suppliers and municipalities with Water Management Act permits by providing funds for planning assistance, demand management, and withdrawal impact mitigation projects in local communities.

AWWA M36 Training Presentation

Statewide AWWA M36 Training provided in June 2019. This presentation provides background information on an AWWA M36 Audit, as well as a detailed step-by-step visual training on performing the audit.

Performance Standards for Public Water Supplies

Residential Gallons per Capita Day (RGPCD) and Unaccounted-for Water (UAW)

The table below lists the 2012 through 2018 residential gallons per capita day (RGPCD) and unaccounted-for water (UAW) values for Massachusetts Public Water Suppliers (PWSs). RGPCD and UAW are performance standards used to measure how efficiently municipal PWSs are operating their systems. Under the authority of the Water Management Act, municipal PWSs using on average 100,000 gallons/day or more over a year are required to calculate the RGPCD and UAW values for their systems in the Annual Statistical Report (ASR) submitted to MassDEP.

RGPCD is the number of gallons of water used, on average, each day by a resident for purposes such as washing clothes, flushing toilets, showering and lawn watering. RGPCD is computed for a public water supply system by dividing the total metered residential use by the number of residents served by that system. Higher RGPCD values may indicate that residents of the system use substantial water for outdoor use, notably lawn watering. Lower RGPCD values may indicate that a community controls outdoor water use or that the community is densely settled with small lawn areas (for example, cities).

UAW is a measure of how well a water supply system can account for all the water that it pumps into its distribution system. It is the percent of water entering the distribution system not accounted for from service meter readings or from unmetered municipal uses such as fire fighting and street cleaning. UAW values may be high because water is lost through leaks in the distribution system, which may occur in older systems. UAW values may also be high if meters are incorrectly calibrated so that over-registration of water use occurs or if unmetered uses are not documented in the ASR.

For many systems, MassDEP accepted the RGPCD or UAW values reported by water suppliers in their ASR. However, for other systems MassDEP adjusted the values due to calculation errors, wrong methodology used, or insufficient documentation. MassDEP re-calculated populations served by systems that do not serve entire municipalities, adjusting the RGPCD values for these systems if appropriate.

The most common reason MassDEP adjusted the UAW values upward is that water suppliers did not provide sufficient documentation of unmetered water used for municipal purposes, such as fire fighting, water main flushing, and water main breaks. Many water suppliers counted water lost to leaks as a municipal use. However, MassDEP considers leaks to be UAW, and therefore discounted leaks as a municipal use, resulting in higher UAW values.

If you have any questions about how the RGPCD and UAW values are calculated, or why MassDEP adjusted the values, please call Jen D'Urso at 617-654-6591 or email her at

Residential Gallons per Capita Day Spreadsheet MS Excel

Residential Gallons per Capita Day Spreadsheet pdf version