The USEPA has provided clear and concise direction for the onsite wastewater treatment industry and regulatory community.  How to treat wastewater from areas not served by centralized municipal plants has received an increasing level of attention in recent years.  These areas use plants called Onsite or Decentralized treatment systems, because the waste is not transported to a central treatment facility.  Treatment often takes place on the site where the waste is generated.  The USEPA has reported that onsite systems can and should be permanent solutions to wastewater treatment.  Perhaps the most prominent example of this is the USEPA RESPONSE TO CONGRESS ON USE OF DECENTRALIZED WASTEWATER TREATMENT SYSTEMS published in 1997.  This document was produced in response to a formal request by the Congressional House Appropriations Committee.

Highlights of the USEPA summary are as follows:

  • “Adequately managed decentralized wastewater systems are a cost-effective and long-term option for meeting public health and water quality goals, particularly in less densely populated areas.”
  • An area of concern is “failing or obsolete wastewater systems in less densely populated areas.”
  • There are many benefits of decentralized systems, with cost-effectiveness being “a primary consideration.”
  • There are several current barriers to the expanded use of decentralized systems, these barriers include: financial barriers, lack of knowledge, public misperception, legislative and regulatory constraints, lack of management programs, liability and engineering fees.
  • The USEPA has ongoing and planned activities to devote funding, education, technology, demonstrations and program development efforts to help small communities meet their wastewater needs by implementing alternatives such as decentralized treatment systems.

As a follow up to the Response to Congress, the USEPA published GUIDELINES FOR MANAGEMENT OF ONSITE/DECENTRALIZED WASTEWATER SYSTEMS.  This document was finalized in March 2003 and establishes a framework for the use of onsite wastewater treatment systems.

To download the Response, Executive Summary or Guidelines, access these files on the USEPA website at  Then select the appropriate tab (Guidance, Manuals or Policies) for the document.

The USEPA has published an update of their ONSITE WASTEWATER TREATMENT SYSTEMS MANUAL.  This publication, otherwise known as the “Purple Manual,” is a widely used reference for the design and application of wastewater treatment technology.  Norweco is cited in the acknowledgements as making a significant contribution to the development of this document.  This document can be found on the USEPA website by using the hyperlink