Applications for additions and alterations are available online (click below) and at the Health District office. They are commonly referred to as "B-100" applications.

Building Application Forms

Requirements for Approval

The first step in determining if a code complying area exists on any lot is to have knowledge of the soils. The Health District or the homeowner may have reliable data that adequately describes the soils and the existing septic system. If not, then typically soil testing must occur. The homeowner must contract with a licensed septic system installer to conduct soil testing. A soil testing application must be completed. This must be performed in the presence of the Sanitarian.


The next step is to submit design plans or an installers sketch demonstrating how the property can accommodate a code complying system. This has to be submitted as part of the application for approval. A sketch or design plan will show in some detail the new or expanded system in its tested expansion area on the lot. In most instances, no upgrade of the system has to occur at the time of house addition, unless the addition results in a substantial increase in design flow, read below:


THE CODE REQUIRES EXPANSION OF THE SEWAGE DISPOSAL SYSTEM AT THE TIME OF THE HOUSE ADDITION WHEN THE ADDITION RESULTS IN MORE THAN A 50% INCREASE IN THE DESIGN FLOW.



You should also be aware that on lots where soil conditions are considered marginal, the homeowner may have to consult with a professional engineer to determine a code complying area.


What happens if the lot cannot meet current Code?
Let's look at instances where the homeowner is unable to demonstrate a code complying area. This is done in two parts.

Part A Building Additions

If a code complying area cannot be demonstrated, building additions may still be approved if all 5 requirements below are met:

• the replacement system meets 50% of leaching area and spread (MLSS) requirements
• the required setback distance to any water supply well is maintained
• the addition does not reduce the potential repair area
• the addition does not increase the design flow and
• all required setback distances to the system are met

Part B Other Additions

Garages, accessory structures, pools, decks, etc.) If a future expansion area cannot be demonstrated, this type of addition could still be allowed if both requirements below are met:

• the structure does not reduce the potential repair area, and
• All required separating distances between the structure and the existing sewage disposal system are met

Building Conversions, Change of Use

In addition to proposals for additions, this regulation also pertains to building conversions or changes in use, such as winterizing a seasonal use residence, or making changes that allows the occupancy or design flow to increase. In theses instances, a code complying area must be demonstrated.

Lot division, line change or reduction

Lastly, this regulation also applies to situations when there is a net decrease in an existing lot's size. For instance, if a single lot splits into two lots, both lots must demonstrate code complying areas. The newly created lot must also demonstrate a reserve area.


This is general information. If you need clarification or more detail, you should discuss with a Registered Sanitarian.

Information on B100

Summarizing the requirements of Section 19-13-B100a of the Connecticut Public Health Code
To view this code in it entirety go to: www.dph.state.ct.us/