NSF/ANSI 40-2023: Residential Wastewater Treatment Systems

Residential waste water treatment systems reintroduce wastewater into the environment—enabling wastewater to become part of the water cycle and accessible for further use. It is therefore paramount that wastewater is treated in order to remove pathogens and other pollutants. NSF/ANSI 40-2023: Residential Wastewater Treatment Systems provides specifications for residential wastewater treatment systems.

What Is A Residential Wastewater Treatment System?

A residential wastewater treatment system is a system that treats domestic flows and returns it to the environment. They are installed much like a traditional septic tank (i.e., a buried, watertight tank designated and constructed to receive and partially treat raw domestic sanitary wastewater) and commonly have a treatment tank similar in size.

Residential wastewater treatment systems are similar to small-scale municipal treatment plants, but they are designed for a single family instead of an entire community or city. They are often used in areas, such as in rural or suburban areas, where centralized wastewater treatment is not feasible.

By creating optimum environments both for microorganisms that digest waste and for collection and storage of the resulting byproducts, the unique design and components of residential wastewater treatment systems accelerate the treatment process. Moreover, their purpose is to treat and reduce the concentration of contaminants in wastewater before it reaches water supplies or people.

What Is NSF/ANSI 40?

NSF/ANSI 40-2023 contains minimum requirements for residential wastewater treatment systems having rated treatment capacities between 1,514 LPD (400 GPD) and 5,678 LPD (1,500 GPD). This American National Standard establishes minimum materials, design and construction, and performance requirements for residential wastewater treatment systems. NSF/ANSI 40-2023 also specifies the minimum literature that manufacturers should supply to authorized representatives and owners, as well as the minimum service-related obligations that manufacturers should extend to owners.

Management methods for the treated effluent discharged from residential wastewater treatment systems are not addressed by this standard.

Certification to NSF/ANSI 40-2023: The Standard for Residential Wastewater Treatment Systems

Residential wastewater treatment systems can be certified to national public health standards like NSF/ANSI 40-2023, which assuring these systems meet health and regulatory requirements. The standard specifies that a certification program for residential wastewater treatment systems should contain the following program elements:

Marking the product—Certified systems should bear a registered certification mark.
Listing certified companies—A listing of all certified systems and components (product description. Class rating, company name and address, etc.,) should be published.
Annual audits—Annual audits of all facilities and production locations of the certified company.
Testing—Testing in accordance with this standard’s requirements prior to certification.
Corrective action—Corrective action for all items of noncompliance found during audits and reevaluation.
Enforcement—Enforcement action by the certifier for recall of all products, general noncompliance, use of a mark on a noncertified product, etc.
Administrative Review—Provisions for an administrative review as requested by any party directly affected by a decision or action of the certifier.
Appeals—Provisions for an appeals process as requested by any party directly affected by a decision or action of the certifier resulting from an administrative review.
Complaints—Provisions for investigation of complaints related to certified products, misuse of the mark by a certified or noncertified company.
Advertising—Proper use of the mark on sales literature, technical publications, promotional materials, packaging, catalogs, and advertising.
Records—Provisions for verification of complete certified company records.
Public Notice—Provisions for issuing a public notice for noncompliance with any requirement of certification.
Confidentiality—Provisions for nondisclosure of any confidential information supplied to the certifier by the company regarding the product, including formulations, components, processes, ingredients, or the identity of the company’s suppliers and distributors.

How Is A Residential Wastewater Treatment System Different Than A Septic Tank?

The primary difference between a septic tank and a residential wastewater treatment system is the internal design and associated mechanical and electrical components that enhance treatment. The effluent (liquid waste or sewage discharged into the environment) generated by the residential wastewater treatment system is greatly superior in its treatment level than a septic tank, allowing for greater flexibility in disposing treated effluent.

Furthermore, it is not sufficient to qualify a septic tank as an effective water treatment plant. This is because wastewater treatment plants contain more than one phase (there is always an additional process following the initial step). A septic tank therefore cannot be used as a wastewater treatment plant. Although both are similar, a residential wastewater treatment system has more efficient treatment processes.

NSF/ANSI 40-2023: Residential Wastewater Treatment Systems is available on the ANSI Webstore.