MassGIS logo

MassGIS maintains a comprehensive, statewide database of spatial information for mapping and analysis supporting emergency response, environmental planning and management, transportation planning, economic development, and transparency in state government operations.

Visit the MassGIS website

Browse all MassGIS data layers

Other Access

The information on this page (the dataset metadata) is also available in these formats.


via the DKAN API

MassGIS Data: Public Water Supplies

April 2019

The Public Water Supply (PWS) datalayer contains the locations of public community surface and groundwater supply sources and public non-community supply sources as defined in 310 CMR 22.00.

Request to download these data
(Shapefile, related tables and ArcGIS layer file)
View in an online map

Sample of MassDEP PWS and WPAsThe public water supply systems represented in this datalayer are based primarily on information in the DEP’s Water Quality Testing System (WQTS) database. The WQTS database is the Department’s central database for tracking water supply data. The PWS datalayer also contains the locations of proposed wells that have a defined DEP approved wellhead protection area (Zone IIs). Proposed sources are not currently tracked in WQTS. In ArcSDE the layer is named PWSDEP_PT.

Massachusetts Drinking Water Regulations (310 CMR 22.00)

As stated in 310 CMR 22.02, a Public Water System means a system for the provision to the public of piped water for human consumption if such system has at least 15 service connections or regularly serves an average of at least 25 individuals daily at least 60 days of the year. Such term includes (1) any collection, treatment, storage and distribution facilities under control of the operator of such a system and used primarily in connection with such system, and (2) any collection or pretreatment storage facilities not under such control which are used primarily in connection with such system. A public water system is either a “community water system” or a “non-community water system.”

  1. Community water system means a public water system which serves at least 15 service connections used by year-round residents or regularly serves at least 25 year-round residents.
  2. Non-community water system means a public water system that is not a community water system.
    1. Non-transient non-community water system or “NTNC” means a public water systems that is not a community water system and that regularly serves at least 25 of the same persons or more approximately four or more days per week, more than six months or 180 days per year, such as a workplace providing water to its employees.
    2. Transient non-community water system or “TNC” means a public water system that is not a community water system or a non-transient non-community water system but is a public water system which serves water to 25 different persons at least 60 days of the year. Some examples of these types of systems are: restaurants, motels, camp grounds, parks, golf courses, ski areas and community centers.

Data Development

The DEP PWS datalayer has been compiled from several sources. The original DEP PWS point dataset contained only community water supplies (CWS) which were located and digitized from stable mylar overlays based on USGS topographic quadrangles. In 1993 locations for community and non-community sources were generated from global positioning system (GPS) data collected by the U.S. Environmental Protection Agency (EPA). The EPA GPS locations were merged with the existing DEP CWS point data to create the DEP PWS datalayer. From June 1996 to February 1997 the DEP GIS Program and Drinking Water Program (DWP) conducted an intensive update of the PWS datalayer. This update involved several methodologies including map interpolation and GPS field verification.


The layer's point attribute table has the following fields:

General Identification Fields:
SOURCE_ID    DWP assigned PWS source identifier (first 7 digits conform to PWSID). The SOURCE_ID is used to relate PWS source locations to WQTS and other DEP PWS datalayers. (see Related Datalayers section below)
SITE_NAME For community sources this is the source name (S_NAME) as listed in WQTS, for non-community sources this is the public water supply name (PWS_NAME) as listed in the WQTS table. For proposed sources, which are not tracked in WQTS, this is the source name as listed in DEP DWP’s Zone II database (see Related Database Files section below).
Geographic Information Fields:
TOWN Town in which the source is located
REGION DEP Region code (1 = Western, 2 = Central, 3 = Northeast, 4 = Southeast)
LATITUDE Latitude in decimal degrees, Clarke1866 Spheroid, NAD27 (actual)
LONGITUDE    Longitude in decimal degrees, Clarke1866 Spheroid, NAD27 (actual)
Other Fields:
TYPE The type of PWS according to WQTS or the DWP Zone II database:
 ESW = Emergency Surface Water
 GW = Community groundwater well
 SW = Community surface water source
 PW = proposed well
 NTNC = Non-Transient Non-community
 TNC = Transient Non-Community.
ZII_NUM DEP DWP assigned ID number of Zone II associated with the source. Corresponds to the ZII-NUM item in the region subclass table (ZONEIIS_REG_ZONE2) of the ZONE II datalayer

Related Datalayers

The PWSDEP_PT feature class should always be used in association with the following related DEP water supply protection datalayers:

DEP Approved Wellhead Protection Areas (Zone II)
PWS sources with assigned Zone IIs are related to the DEP Approved Wellhead Protection Area (Zone II) datalayer by ZII_NUM. Please note that multiple PWS sources may be associated with one Zone II.

MassGIS Data - MassDEP Wellhead Protection Areas (Zone II, Zone I, IWPA)
Although there is no database relate between the PWS sources and the IWPA datalayer, it is important to always display IWPAs with DEP PWS point data on any map or project.

MassGIS Data - Surface Water Supply Protection Areas (ZONE A, B, C)
Surface water supply protection areas are related to the PWS surface water source points by SOURCE_ID. Surface water protection areas are assigned to active and inactive surface water sources (TYPE = ‘SW’), but not to emergency surface water sources (TYPE = ‘ESW’). This layer replaces the now discontinued MassDEP ZONEA_POLY, ZONEB_POLY and ZONEC_POLY layers.

MassGIS Data - Surface Water Supply Watersheds
Contains the watershed extents for all surface water supplies including active, inactive, emergency, sources outside of Massachusetts, watersheds that extend into other states and watersheds of sources from other states that extend into Massachusetts. Surface water intakes on Class B Rivers are not included.

Related Database Tables

Several relatable database files are provided for the purpose of linking DEP PWS source locations with more detailed PWS attribute information and to provide standard DEP GIS metadata. Files are also provided for relating to the MassGIS drainage sub-basins datalayer, for the purpose of defining the contributing watersheds for DEP PWS surface water sources.


The PWS_DEP.WQTS table contains information downloaded from the DWP Water Quality Testing System (WQTS) Oracle database. WQTS is DEP’s comprehensive repository for PWS information. The WQTS database contains many other data items that are not in the PWSDEP_PT_WQTS relate file. This table was designed for use by the DEP GIS Program to maintain the PWS datalayer in close relation to WQTS. Current fields include:

REG_OBJ_ID DEP Facility Master File (FMF) Regulated Object ID – Unique Identifier
SOURCE_ID PWS source Identification number
PWS_NAME Water supplier name – conforms to SITE-NAME for non-community sources
S_NAME Source name, conforms to SITE-NAME for community sources
PWS_STATUS Water supplier status:
  A = Active
  I = Inactive
  D = Declassified
According to DEP Drinking Water Program a Declassified system is no longer considered a PWS by the DEP, but has not gone through the official process of abandoning all sources.
S_STATUS Source status:
  A = Active
  I = Inactive
  D = Declassified
According to DEP Drinking Water Program a Declassified system is no longer considered a PWS by the DEP, but has not gone through the official process of abandoning all sources.
PWS_CLASS Source classification:
  COM = Community surface and groundwater sources
  NTNC = Non Transient Non Community
  NC = Transient Non Community
S_AVAILABI Source availability (ACTIVE, INACT, EMERG, ABAND). Abandoned (ABAND) sources are NOT maintained in PWS_DEP.

Only sources coded in WQTS as having Active (ACTIVE), Inactive (INACT) or Emergency (EMERG) availability (see: S_AVAILABI field) are maintained in PWS_DEP. As stated in 310 CMR 22.02:

  1. An Active Source means an approved source(s) used for primary or backup purposes to meet consumer demands as necessary.
  2. An Inactive source means an approved source(s) which is expected to be off-line for at least one year (12 months). A source may be deemed inactive only upon written approval of the Department.
  3. An Emergency source means any source of water used to supplement or temporarily replace a public water system’s active or inactive source(s) when water of sufficient quality or quantity is not available.

Sources listed as abandoned (ABAND) in WQTS are removed from the PWS datalayer. Sources in WQTS that are coded as abandoned include both abandoned and decommissioned wells. Abandoned sources are no longer in use or are otherwise unfit for the purposes of water supply. Abandoned sources have been physically disconnected from the distribution system but have not undergone DEP’s formal decommissioning process. Decommissioning requires physically rendering the source incapable of water supply delivery.


The PWSDEP_PT_Z2DAT table contains information from the DEP DWP Zone II Database. Fields include:

WELLNAME Source name
PURVEYOR Water supplier name
BASIN Major drainage basin in which the PWS source is located
REGION DEP Region identification number:
 1 = Western
 2 = Central
 3 = Northeast
 4 = Southeast
METHOD Method in which the Zone II was delineated
AQUIFER Type of aquifer that comprises the Zone II
PRG DEP DWP program under which the Zone II was approved
SUB_DATE Date the Zone II was submitted to DEP DWP for approval
APP_DATE Date that the Zone II was approved
GPM Source pumping rate in gallons per minute (GPM)
STATUS Current Zone II status:
 C = Current
 S = Superseded
SYSTEM PWS Classification:
 COMM = Community
 NC = Non Community
WHP_CNTRL Existing wellhead protection plan (Y = Yes, N = No)
BYLAW_DATE    Date of Bylaw approval containing well head protection plan
SOURCE_ID DEP PWS source ID (see SOURCE-ID description for PWS_DEP)
ZII_NUM DEP DWP assigned ID of the Zone II protecting a source(s)


Table is no longer supported. Use MassGIS Data - Surface Water Supply Protection Areas (ZONE A, B, C) (SWP_WATERSHEDS_POLY)


The PWSDEP_PT_DRSBASINS table links direct river sources to the MassGIS drainage sub-basins datalayer using the item SUB_ID. Direct River Sources (DRS) are PWS surface water supplies (TYPE = 'SW' and 'ESW') with intakes located on Class B rivers. Fields include:

SOURCE_ID    DEP PWS source ID (see:SOURCE-ID description for PWS_DEP)
SUB_ID Drainage sub-basin identification number that contributes to the surface water supply
REGION DEP Region identification number in which the surface water supply intake is located:
 1 = Western
 2 = Central
 3 = Northeast
 4 = Southeast
TOWN_ID MassGIS town identification number in which the surface water supply intake is located
BAS_ID MassGIS major drainage basin identifier (see: MassGIS Data - Major Drainage Basins data layer documentation) in which the surface water supply intake is located
PWSID DEP public water supplier or system identification number (First 4 digits are DEP Region ID, followed by MassGIS Town ID)


The DEP GIS Program, in cooperation with DEP Drinking Water Program (DWP) maintains this datalayer. Updates are made on a quarterly (Dec., Mar., June, and Sept.) basis, in accordance with the DWP’s PWS new PWS source approval schedule. The updated datalayer is then shared through MassGIS. As a standard component of this quarterly update, The DEP GIS Program removes abandoned sources in accordance with WQTS. The addition of new PWS sources is dependent on locational information made available by the DEP DWP at the time of quarterly update. Datalayer updates may also include refinements to existing PWS source locations.

If you have questions regarding this datalayer, please contact the DEP GIS Program at (617) 556-1115 or (617) 574-6856. General and technical questions regarding public water supplies or Massachusetts drinking water regulations should be directed to the DEP DWP (617) 556-1055.

Last Updated 4/11/2019


Modified Date
Release Date
Spatial / Geographical Coverage Location
MassGIS (Bureau of Geographic Information)
Contact Name
Contact Email
Public Access Level
Data Quality