Water Conditioning & Purification Magazine

Update on NSF/ANSI 419 Public Drinking Water Equipment Performance – Filtration

By Rick Andrew

In January, this column introduced a new draft standard from NSF in the area of water treatment. When the column was written in early December 2014, NSF 419 Public Drinking Water Equipment Performance–Filtration was undergoing the ballot process to become an NSF standard and subsequently an NSF/ ANSI standard. Since then, the ballot process has successfully completed and the new standard was published in January. The purpose of the standard is to provide a performance evaluation test procedure for the product-specific challenge testing of fullscale UF and MF membrane modules, bag filters and cartridge filters for the removal of microbial contaminants. It provides procedures to develop challenge testing Log Removal Values (LRVC_TEST), as required in US EPA’s Long Term 2 Enhanced Surface Water Treatment Rule (LT2 Rule) published in 40 CFR 141-subpart W.

Technologies included

The LT2 Rule requires community water systems to use treatment technologies to reduce exposures to Cryptosporidium originating in surface water and it applies to all public water systems that use surface water or groundwater that is under the direct influence of surface water. The LT2 Rule also requires membrane filtration and UV products to undergo testing in the laboratory to confirm the systems perform as specified. The treatment technologies include the following:

Demonstrating conformance

Community water systems have a challenge to demonstrate that they are in conformance with LT2 requirements. Often, this is being accomplished through a patchwork of various test reports, calculations and other documents assembled through equipment vendors. These test reports can come from a variety of laboratories or engineering firms, with testing being conducted under a range of conditions and procedures. Sometimes all of this must be developed prior to installation if a community water system seeks to install equipment that is new to the market and has not been previously tested. Questions can be raised by a number of stakeholders throughout the approval process, leading to delays for equipment vendors and for community water systems as they work to bring treatment facilities online, leading to delays for consumers in receiving water from the new treatment system. All of this adds up to a situation that is less than ideal.

There can be gaps in establishing conformance above and beyond review of test reports and procedures. The LT2 Rule includes non-testing requirements for internal manufacturing quality control. A review of test results, calculations and documentation does not provide assurance that the manufacturing quality control procedures are in place and are in accordance with the test results. Another gap is that changes to the product or manufacturing process can occur at any time. It can be unclear as to whether previous testing results are brought into question or even invalidated based on these changes. There is no way for those reviewing test results to understand what changes, if any, have occurred since the testing was performed or what the impact on product performance related to those changes might be. Overall, this situation is a textbook case for a situation in which certification to a standard would be a valuable approach for all of the stakeholders: community water systems, equipment manufacturers and consumers.

Figure 1. Basic requirements of draft NSF/ANSI 419
Materials in contact with drinking water must conform to NSF/ANSI 61
Performance test methods for:
Bag filters
Cartridge filters
UF modules
MF modules
Microbiological surrogates:
Bag and cartridge filters
  — Polystyrene microspheres for Cryptosporidium
UF and MF modules
  — B. atrophaeus endospores for Cryptosporidium 
  — MS-2 coliphage for virus 
MS-2 coliphage enumeration method
Polystyrene microsphere enumeration method
Quality assurance
Data management, analysis and reporting

Advantages of certification

Certification to a standard provides significant advantages for various stakeholders seeking to establish and verify conformance to requirements. It provides clear, transparent criteria, processes and policies related to conformity assessment. Testing procedures, calculations and documentation requirements are standardized and clarified. The basic requirements of draft NSF/ANSI 419 are described in Figure 1. Additionally, continuity in manufacturing practices is confirmed through certification facility audits and technical reviews to address the potential impacts of any changes in the manufacturing process, with retesting being required when justified by a technical review. The facility audits also address the internal manufacturing quality control criteria specified by the LT2 Rule.

Material safety verification

The LT2 Rule focuses entirely on product performance associated with treatment of microbial contaminants in the drinking water. It does not address the safety of materials of construction of these products for contact with drinking water. For most non residential products treating drinking water in most US states, however, third-party certification to NSF/ANSI 61 is required. Therefore, NSF/ANSI 419 requires that materials in contact with drinking water must also conform to NSF/ANSI 61.

Filling a need

The LT2 Rule established a set of requirements for equipment used in public water supplies. Equipment manufacturers are addressing these requirements by developing, manufacturing and selling systems to allow community water systems to conform to these requirements. Until recently, demonstration of conformance to the requirements has been a challenge for all stakeholders: community water systems, state or other regulatory bodies and manufacturers of treatment equipment.

This type of challenge is perfectly addressed by development of national consensus standards and third-party certification to those standards. By bringing stakeholders together to develop robust, clear and transparent requirements, acceptance of these products and their demonstration of capability can be dramatically simplified and bolstered. NSF/ANSI 419 Public Drinking Water Equipment Performance–Filtration is now filling that need. In fact, there are now five manufacturers with a total of 17 products certified to this standard (http://info.nsf.org/Certified/pdwe/Listings.asp), with more certifications in process. NSF looks forward to continuing to develop this certification program so that it becomes an efficient and valuable tool for establishing conformance to the LT2 Rule requirements across the nation.Writing: Rick Andrews

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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