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Water and Sewer Service Categories

The County's Water and Sewer Plan assigns a water category and a sewer category to every property in the County. These service area categories serve two functions:

  1. They identify areas approved or planned for community water or sewer service and areas intended for service by individual (on-site) systems

  2. They identify a mechanism for staging community service for those areas planned for community service.

The mechanism consists of the use of service area categories W-1 through W- 5 (for water) and S-1 through S-5 (for sewer).


Who Needs to Know Their Service Area Categories?

Most property owners are completely unaware of the water and sewer categories assigned to their land in the Water and Sewer Plan. In fact, most don't even know they're in a service area category. The need to know a service area category (and what it means) usually comes up in three types of situations:

  1. An owner getting ready to sell a property wants to complete the Real Estate Disclosure Form concerning water and sewer service, which requires the property's service area categories. In most disclosure inquiries directed to DEP, the property has existing public water and sewer service and the corresponding service area categories are W-1 (for water) and S-1 (for sewer).

  2. A property owner wants to develop or redevelop a piece of land and needs to know whether the County has planned for public water and sewer service or wells and septic systems to serve the property.

  3. A property owner using a private, on-site system (well and septic) wants to change over to service from a public water and sewer system.


Changing Water and Sewer Categories

Once property owners or developers determine the water and sewer categories designated for their properties, they're not always satisfied with them. Most often it's because those categories won't allow for the use of public water and sewer service on the property. A major part of DEP's work regarding the Water and Sewer Plan involves requests from property owners to change the water or sewer categories for their properties. Often these category change requests are requests to allow public service in an area designated for private, on-site systems.

Visit the Service Area Category Changes page to learn more about how to change a service area category.


Designations and Definitions

The Water and Sewer Plan classifies almost all properties in the County into one of the following water categories and one of the following sewer categories. (The exception is rights-of-way for public roads, railroads, and gas and electrical transmission lines.) Note that the County does not necessarily designate properties with matching water and sewer categories, such as W-3 and S-3. (For example, a property could have a water supply category of W-1 and a sewer service category of S-6.)


The following table provides definitions and information on the County's water and sewer service area categories:


Water and Sewer Service Area Categories
Service Area Categories Category Definition and General Description Service Comments



Areas served by community (public) systems that are either existing or under construction. Category 1 may include properties or areas for which community system mains are not immediately available or which have not yet connected to existing community service.

Properties designated as categories 1 and 3 are eligible to receive public water and/or sewer service.

New development and properties needing the replacement of existing wells or septic systems are generally required to use public service. Properties with wells or septic systems on interim permits are required to connect to public service within one year of its availability.

Where water and/or sewer mains are financed under the front foot benefit system, the Washington Suburban Sanitary Commission (WSSC) will assess front foot benefit charges for mains abutting these properties unless the property has a functioning well and/or septic system. WSSC provides public water and sewer service throughout the County, except where service is provided by systems owned by the City of Rockville or the Town of Poolesville.



Categories W-2 and S-2 are not used in the Montgomery County Water and Sewer Plan. (State's definition: Areas served by extensions of existing community and multiuse systems that are in the final planning stages.)



Areas where improvements to or construction of new community systems will be given immediate priority and service will generally be provided within two years or as development and requests for community service are planned and scheduled.



Areas where improvements to or construction of new community systems will be programmed for the three- through six-year period. Category 4 includes areas generally requiring the approval of capital improvement plan (CIP) projects before service can be provided.

WSSC will not serve properties designated as category 4 or 5, but will work to program water and/or sewer projects needed to serve these areas. Permits for new wells and/or septic systems for category 4 properties will be interim permits. (See above for further information.) DEP may require that development proceeding on interim wells and septic systems in category 4 areas also provide dry water and sewer mains and connections.

Where water and/or sewer mains are financed under the front foot benefit system, WSSC will assess front foot benefit charges for abutting properties designated as category 4 unless the property has a functioning well and/or septic system. WSSC will not assess front foot charges for properties designated as category 5.



Areas where improvements to or construction of new community systems is planned for the seven- through ten-year period. This category is frequently used to identify areas where land use plans recommend future service staged beyond the scope of the six-year CIP planning period.



Areas where there is no planned community service either within the ten-year scope of this plan or beyond that time period. Category 6 includes all areas not designated as categories 1 through 5. It includes areas that are planned or staged for community service beyond the scope of the plan's ten-year planning period and areas that are never expected to have community service on the basis of adopted plans. WSSC will neither provide service to nor assess front foot benefit charges for properties designated as category 6. Development in category 6 areas is expected to use private, on-site systems.


View a printable version of the Service Area Category Designations and Definitions table (MS Word).


Finding Your Water and Sewer Categories


Map Viewer Update Notice (11/10/15): The County’s Department of Technology Services (DTS) has launched a new version of the County Map Viewer application and has recently added water and sewer category information.

You can contact DTS staff for more information about the Montgomery County Map Viewer at

Just as the County's zoning maps are the record of zoning decisions, the water category and sewer category maps show, in a geographic format, the service area categories designated throughout the County. You can find your service area category using the County Map Viewer application—an interactive mapping application (available from the DTS mapping applications on the Net.)

To open the Map Viewer application, click on the following link,, to access the DTS homepage.

Using the application (keyed to the image below):

  1. To navigate around the map viewer: Use the zoom in (+) and zoom out (-) buttons

  2. To locate a property using a street address: enter the address in the box shown and “Enter”. The map image will pan to that location.

  3. Click on the “Layer” button and choose either “Sewer Category” or “Water Category” separately.

  4. To see the color legends for Water Categories” or “Sewer Categories”, use the scroll bar.


For additional information about water and sewer service area categories for specific locations, please contact DEP staff at (preferred) or 240-777-7716. 

Screen shot of the Montgomery County Map Viewer application