Water Conditioning & Purification Magazine

NSF/ANSI Standards for Onsite Wastewater Equipment

By Rick Andrew

Onsite wastewater technology varies across a broad spectrum, from simple septic tanks to much more sophisticated advanced treatment systems. Effective operation of these advanced treatment systems is very important because they are typically deployed in sensitive environments, such as near rivers and other bodies of water that could be negatively impacted by untreated wastewater discharge.

As such, a number of standards have been developed by the NSF Joint Committee on Wastewater Technology. A list of these standards can be found in Figure 1.

The first to be developed, NSF/ANSI 40 Residential Wastewater Treatment Systems, was adopted way back in 1970 and continues to be updated to address advances in treatment technology, as well as changes in regulations. In addition to addressing the wastewater treatment performance of these systems, it additionally includes requirements for materials, design and construction, and product literature that manufacturers must supply to authorized representatives and wastewater treatment system owners. An additional aspect of NSF/ANSI 40 is that it includes service-related obligations that manufacturers must provide to system owners.

NSF/ANSI 41 Non-liquid Saturated Treatment Systems, first adopted in 1978, was developed as a follow-on to NSF/ANSI 40 and like NSF/ANSI 40, has been continually updated over the years to remain current in terms of both technology and regulations. This standard addresses systems that do not use a liquid-saturated media to store or treat waste. Most of the systems conforming to this standard are used in seasonal applications with limited capacity. In fact, the standard divides end uses into categories of residential, day-use and cottage. It addresses materials, design and construction, performance and the literature that must be provided to authorized representatives and system owners.

As with the overall filtration industry, components of wastewater systems are an important consideration. As such, the NSF Joint Committee on Wastewater Technology developed NSF/ANSI 46 Evaluation of Components and Devices Used in Wastewater Treatment Systems to address them. First adopted in 1997, the standard covers grinder pumps and related components, filtration devices for residential gravity-flow septic tank systems, chlorination devices, UV disinfection devices and ozone generation devices. The standard includes materials, design and construction, and performance requirements for each of these types of components.

Onsite wastewater treatment systems specifically intended to reduce nitrogen in wastewater are addressed through NSF/ANSI 245 Residential Wastewater Treatment Systems–Nitrogen Reduction. Adopted more recently (2007) than the previous standards, NSF/ANSI 245 includes requirements for residential wastewater treatment systems capable of treating 400 to 1,500 GPD (1,514 to 5,678 L/day). In addition to reducing nitrogen in residential wastewater, systems conforming to NSF/ANSI 245 must also conform to NSF/ANSI 40. Interestingly, NSF/ANSI 245 is applicable to not only more typical systems, but also to natural systems involving features such as vegetation and wetlands. Similar to NSF/ANSI 40, the standard includes requirements for materials, design and construction, and product literature that manufacturers must supply to authorized representatives and wastewater treatment system owners.
NSF/ANSI 350 Onsite Residential and Commercial Water Reuse Treatment Systems, the most recent of the NSF wastewater standards, was first adopted in 2011 and has been updated since then to remain current. It covers a variety of onsite residential and commercial water reuse treatment systems, specifically:

  • Greywater treatment systems having a rated treatment capacity up to 1,500 GPD, applying to onsite residential and commercial treatment systems that treat greywater, those that treat laundry water from residential laundry facilities and those that treat bathing water.
  • Residential wastewater treatment systems having a rated treatment capacity up to 1,500 GPD, applying to onsite residential treatment systems that treat combined wastewater generated by the occupants of residence(s). It is important to note that a reuse system treating 400 to 1,500 GPD must meet the requirements of NSF/ANSI 40. A reuse system treating less than 400 GPD is not required to meet those requirements.
  • Commercial treatment systems, which include onsite commercial treatment systems that treat combined commercial facility wastewater and commercial facility laundry water of any capacity and those treatment systems that treat greywater from commercial facilities with capacities exceeding 1,500 GPD. These systems are performance-tested and evaluated at the location of the reuse system installation, using the wastewater generated onsite from the facility serving the treatment system.

The standard defines two classes of systems, Class R (single-family residential) and Class C (multi-family residential and commercial), with possible end uses for reused water that include toilet and urinal flushing, and surface irrigation. Similar to the other NSF wastewater standards, NSF/ANSI 350 includes requirements for materials, design and construction, and product literature that manufacturers must supply to authorized representatives and to wastewater treatment system owners.

A standard that many people find very interesting is NSF P157 Incinerating Toilet Systems–Health and Sanitation. First published in 2000 and updated since to stay current, P157 establishes minimum requirements for health and sanitation characteristics of electrical, gas or oil-fired incinerating devices designed to combust toilet waste. It contains minimum requirements for materials, design and construction, and performance of incinerating devices used to treat household human waste. It also requires that if other wastewater is generated, it must be disposed of in accordance with applicable rules and regulations.

A suite of standards
These standards together form a comprehensive suite of criteria for evaluation of advanced onsite wastewater technologies, which are so important in those sensitive areas where traditional septic systems are not possible or practical. These standards have tremendous value because these technologies are complex and difficult to assess in terms of effectiveness without generally accepted testing approaches. With these standards, end users, regulators and manufacturers can all have confidence that conforming products will perform in a safe and environmentally protective manner. This confidence allows all of the stakeholders to make well-informed decisions in the design phase, as opposed to having to wait until installation and hoping for successful onsite testing results in the field.

About the author
Rick Andrew is NSF’s Director of Global Business Development–Water Systems. Previously, he served as General Manager of NSF’s Drinking Water Treatment Units (POU/POE), ERS (Protocols) and Biosafety Cabinetry Programs. Andrew has a Bachelor’s Degree in chemistry and an MBA from the University of Michigan. He can be reached at (800) NSF-MARK or email: Andrew@nsf.org

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