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Project Highlights

  • Sensors will measure nitrate, nitrite, ammonia, or Total Nitrogen.
  • Sensor data compared to certified laboratory results.
  • Maximum sensor cost: $1,500.

The EPA Advanced Septic System Nitrogen Sensor Challenge seeks to spur market development of an accurate and precise low-cost sensor to measure nitrogen compounds in wastewaters associated with onsite septic systems.


Conventional septic systems are often not designed to remove nitrogen to levels that are protective of local water quality, which can lead to problems like excess nitrogen loading to waterways. This issue is especially important to coastal communities, where excess nitrogen can cause eutrophication, hypoxia, and toxic algal blooms leading to beach closures and other issues that negatively affect coastal communities. EPA estimates that over 2.6 million existing systems could be good candidates for upgrade to advanced septic systems that treat the nitrogen due to their location in nitrogen-sensitive watersheds. Adding nitrogen sensors to these advanced septic systems will help manufacturers, homeowners, local and state governments know that these systems are performing as intended and protecting valuable coastal resources.

The Challenge – Phase I

In January 2017, EPA partnered with The Nature Conservancy, USGS and others to launch Phase I of the Advanced Septic System Nitrogen Sensor Challenge. Phase I challenged entrants to design a nitrogen sensor for use in advanced nitrogen-removing onsite wastewater treatment systems, also known as advanced septic systems, to monitor their long-term performance. Phase I was open through mid-March 2017, and written proposals were judged by an external panel of experts. EPA hosted a Sensor Showcase Day on June 29, 2017 and awarded prizes.

Prototype Testing – Phase II 

EPA launched prototype testing in December 2017. Prototype testing was open to any sensor technology developer with a nitrogen sensor for advanced septic systems. EPA selected Battelle Memorial Institute to support the Prototype Testing Program by developing a Test/Quality Assurance Plan (T/QAP) and Verification Plan and overseeing the testing of the sensors. The T/QAP is based on the International Organization for Standardization (ISO)  Environmental Technology Verification (ETV) Standard – ISO 14034. Funding for the testing program is from EPA’s Office of Research and Development and EPA’s Office of Water and the Office of Wastewater Management.

Sensor testing was  conducted at the Massachusetts Alternative Septic System Test Center, a National Sanitation Foundation certified test facility in Barnstable, Massachusetts, from 2018 through 2019. The last Challenge test occurred between  August 21-27, 2019, for which EPA offered up to $50,000 in prize money to the best performing sensor during the August test…

More information can be found on the EPA’s website.

Contaminants Addressed

  • Nitrogen