Four Plumbing, Building Codes Adopt NSF/ANSI 350 Standard for Water Reuse Systems

Codes require that water reuse systems used for residential toilet and urinal flushing comply with standard

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Four international plumbing and building codes now require that water reuse systems comply with NSF Intl.’s standard for water reuse systems. NSF Intl., a global public health organization, developed NSF/ANSI 350: Onsite Residential and Commercial Water Reuse Treatment to standardize the material, design and performance criteria for water reuse systems.

The 2015 International Residential Code (IRC), International Plumbing Code (IPC), Uniform Plumbing Code (UPC) and International Green Construction Code (IgCC) now all require that water reuse systems used for residential toilet and urinal flushing comply with the NSF/ANSI 350 standard.

Water reuse systems reduce costs associated with energy and water use by treating water onsite. In areas such as California where water scarcity is a growing concern, these systems can provide an additional source of critically needed water and reduce the strain on municipal resources.

Under these codes, should a builder choose to use an onsite water reuse system, certification to NSF/ANSI 350 is either required or constitutes a path to acceptance under these codes. NSF/ANSI 350 certification ensures that water for toilet and urinal flushing (and in some codes for surface irrigation) is properly treated for use in these applications.

NSF/ANSI 350 establishes material, design, construction and performance requirements for onsite residential and commercial water reuse treatment systems. It also sets water quality requirements for the reduction of chemical and microbiological contaminants for non-potable water use. Treated greywater can be used for restricted indoor water use such as toilet and urinal flushing and for outdoor unrestricted water use such as lawn irrigation.

The standard requires 26 weeks of continuous testing with regularly scheduled sampling throughout, typically three days a week. This lengthy testing time with high sampling volume is designed to assess the reliability of the treatment system product over time.

“The inclusion of NSF/ANSI 350, the American National Standard for water reuse treatment systems, in these important international plumbing and building codes is further recognition of the rigor of the NSF Intl. standard and its effectiveness in helping these technologies gain use and acceptance in the marketplace. Water scarcity is a growing global issue and ensuring certified water reuse systems properly treat greywater will be an essential part of the solution,” said Jessica Evans, director of standards development at NSF Intl. 

“The International Green Construction Code has also adopted many other NSF/ANSI sustainability standards for carpet, wall coverings, resilient flooring, textiles, roofing and stone,” she added.


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