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Can I add a bedroom or bathroom if my house is on a septic system?

Can I add a bedroom or bathroom if my house is on a septic system?

  • Generally speaking, unless your septic system was designed with additional capacity, any addition to your home will require modification or replacement of your septic tank and/or soil absorption system (leaching field or trench).  Additions to a home served by a septic system must be reviewed and approved by the GEPA Water Pollution Control Program and Chief Engineer, as part of a DPW Building Permit Application.  You should coordinate with GEPA as early as possible if planning an addition, and have your engineer or architect discuss the situation with GEPA staff to determine if percolation tests will be required.  Make sure to find your “as-built” drawings showing the dimensions of your existing septic system for review during the design process.  If you can’t find these drawings, it is more likely that a new leaching field will be required to ensure you have adequate soil absorption area for the planned addition.


  • Additions to a home that do not increase the number of bedrooms (for example a kitchen remodel, an office, or a new living room) do not require modification of the existing septic system.


  • Keep in mind, also, that no addition may be built on top of a septic tank or leaching field, and the 10 foot setback from the building to the septic tank and 20 foot setback to the soil absorption system must be maintained.  In addition, the 100% reserve leaching field area and its setbacks must be preserved to account for the possibility of future system failure.  On a small lot, this may impose a significant limit on the size of any proposed addition.


  • If you do not have adequate space available to re-size your septic tank and soil absorption system to accommodate your proposed addition, the addition will not be permitted by GEPA pursuant to 22 GAR §12105(e) & (f).

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