Sign In
Maryland State Government Maryland Department of the Environment

Maryland's Nitrogen-Reducing Septic Upgrade Program

There are approximately 420,000 septic systems in Maryland. Of these, 52,000 systems are located within the “Critical Area,” land within 1,000 feet of tidal waters. The typical septic system does not remove nitrogen, instead delivering about 23.2 pounds of nitrogen per year to the groundwater. An upgraded, nitrogen-removing septic system cuts a system’s nitrogen load in half.  The Maryland Department of the Environment has upgraded over 8,000 septic systems to nitrogen removing Best Available Technology (BAT) through the Bay Restoration Fund (BRF) Onsite Sewer Disposal System (OSDS) grant program.

In accordance with State Law, the Bay Restoration Fund prioritizes upgrades as follows:

  1. Failing OSDS in the Critical Areas
  2. Failing OSDS outside the Critical Areas
  3. Non-conforming OSDS in the Critical Areas
  4. Non-conforming OSDS outside the Critical Areas
  5. Other OSDS in the Critical Areas, including new construction
  6. Other OSDS outside the Critical Areas, including new construction


For more information on grant implementation, please visit the following links:


Best Available Technology (BAT) Classifications

           Waterless Toilet Systems Application Process and information


The following checklists may be used while doing site inspections and operation and maintenance of BAT Class IV. These are for reference to use when onsite. These checklists were copied from the Consortium of Institutes for Decentralized Wastewater Treatment, Residential Onsite Wastewater Treatment Systems: An Operation and Maintenance Service Provider Program, Second Edition.


Best Available Technology (BAT) Information


Chesapeake Bay States - Data Sharing

On April 16, 2015, the states of Delaware, Maryland, Pennsylvania, Virginia and West Virginia signed a Memorandum of Cooperation to share data developed to document the performance of advanced onsite pretreatment units for nitrogen reduction and, therefore, to simplify and expedite the approval processes for these technologies in each individual state, as well as reduce costs to residents and manufacturers. Prior to this MOC, all states nationwide approved systems on an individual basis and many did not take into account data collected by other state programs. To learn more about data sharing, visit the Chesapeake Bay Program website.


OWTS Expert Panel

The On-Site Wastewater Treatment Systems (OWTS) Nitrogen Reduction Technology Expert Review Panel was tasked with identifying and recommending on-site wastewater treatment systems that would reduce total nitrogen (TN) loads to the Chesapeake Bay watershed. For more information on the recommendations of the panel, please visit the link below.


County Reporting Form (Grant Administrator use only)

Field-verified Sampling Results

Contact Info

If you have additional questions or would like more information, please contact the Wastewater Permits Program - Onsite Systems Division at 410-537-3778.

Related Links 


The Maryland Department of the Environment thanks you for your continued interest and support of this important program!

Get Acrobat ReaderAcrobat® Reader is required to view and print the PDF files. If you do not have it click on the icon to the right.