WS 23, 24: Approval to Construct a Water Treatment Facility

Approval to build a treatment facility

MassDEP Drinking Water Program


Program Director 617-292-5770


MassDEP Drinking Water Program

The Details

What you need

These approvals serve to protect the public health by ensuring that the application meets minimum drinking water requirements and conforms to current Division of Water Supply guidelines and policies contained in Guidelines and Policies for Public Water Systems . This publication is available at the State House Bookstore.

Apply in category WS 23 A, B, or C if your facility will treat less than one million gallons per day.  The specific subcategory is determined by the design capacity of the system:

  • WS 23A:  less than 40,000 gallons per day (gpd)
  • WS 23B:  40,000 gpd or more and less than 200,000 gpd
  • WS 23C:  200,000 gpd or more and less than 1 million gpd

Apply in category WS 24 if your facility will treat more than one million gallons per day. Legislative authority for both approvals is stated in MGL Chapter 111, section 160A. Regulatory authority for these approvals is stated in 310 CMR 22.04.

Public water systems (PWS) or their designated representatives seeking approval to construct a treatment facility.

If the PWS or their representative applies for either of these permits it may be necessary to apply for other water treatment permits, e.g. WS 21, 22, or 25.

Approvals of this type may require Massachusetts Environmental Policy Act (MEPA) Office review. Please carefully examine 301 CMR 11.00, the MEPA Regulations, to determine if your project exceeds the MEPA review thresholds, or for more information contact the MEPA Office of the Executive Office of Environmental Affairs (100 Cambridge Street, Suite 900, Boston, MA 02114; (617-626-1020).  If MEPA review is required by regulation, MassDEP cannot begin technical review of the application until the MEPA process has been completed, unless otherwise agreed to in writing. Copies of MEPA filings (with reference to any applicable Transmittal numbers) should be sent to the MEPA Coordinator in the appropriate Regional Office.

Note: These additional requirements are intended to serve as a guide to the applicant. It does not necessarily include all additional requirements.

How to apply

See details below.

Next steps

  1. Review the Instructions

    Guidance on how to prepare your application, including a completeness checklist.

  2. Complete the Application Form

    You may fill out and save the Microsoft Word form on your computer. The PDF version has to be printed out and completed by hand.

  3. Obtain a Transmittal Form and Number

    A unique Transmittal Number is needed for each application you submit to MassDEP.

  4. Lookup the Permit Application Fee

  5. Mail Your Application and Fee Payment

    Submit your application fee payment and a copy of your Transmittal Form to:

    Department of Environmental Protection
    PO Box 4062
    Boston, MA 02211

    Submit your completed, signed application and your original Transmittal Form to the appropriate MassDEP Regional Office (see listing below).



MassDEP Boston
1 Winter Street, Boston, MA 02108


Program Director 617-292-5770


MassDEP Drinking Water Program


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