COVER SERIES | Pottable Water
NSF Certification & Potable Water Pumps
What engineers and operators need to know about NSF 61.
Ron Aceto | Cornell Pump
Potable water is water that is safe for human consumption, including drinking, cooking and food preparation. Safe/potable water has always been a concern, as millions upon millions of people have suffered and died because of contaminated water. Civilizations have collapsed because of fouled water, and communities worldwide still struggle with this basic need.
Many engineers and operators have seen requirements for National Sanitation Foundation (NSF) 61 certification for freshwater systems. The designation is now shaping the industry far beyond municipal drinking water supply, extending into agricultural irrigation, rental dewatering applications, food processing water systems and even the wastewater side of municipal operations. In an interconnected system of aquifers, rivers and springs, one person’s wastewater can quickly become someone else’s source for drinking water.
This article will look at how NSF certification relates to pump systems, examine challenges operators can face, touch on best practices for compliant installations and explore the trends in NSF pump systems.
What Are NSF & NSF/ANSI 61?
Founded in 1944 as the National Sanitation Foundation, NSF International is an independent, not-for-profit organization that develops public health standards and certifies products to ensure safety and compliance. Working in collaboration with industry, regulators and end users, NSF helps protect and improve human health, with many standards applying not only in the U.S., but also North America and many parts of the Middle East and Asia.
NSF/ANSI 61: Drinking Water System Components is a key standard that establishes health effect requirements for materials and components that come into contact with potable water. NSF develops standards jointly with organizations such as the American National Standards Institute (ANSI). It sets limits on contaminants that may leach into drinking water from products such as pipes, valves, pumps, coatings and treatment equipment. NSF tests and certifies products to these requirements to help ensure safe, clean drinking water across municipal and industrial systems.
Centrifugal pumps, along with piping, valves and fittings, are components covered under NSF 61 when they are used in contact with potable water. In centrifugal pumps, any wetted components, such as impellers, drive shafts and pump volutes, are covered by NSF. Additionally, such items as lock screws, flange covers, seals and even coatings are also subject to the NSF standard. This helps ensure the contamination is addressed in any material that could contact potable water.
Materials of construction, such as cast iron, stainless steel, bronze and various engineered polymers, need to be tested to ensure they pass contamination leaching testing. In order to be certified, a manufacturer first submits an application and product list to a testing house such as NSF, Underwriters Laboratories (UL) or the Water Quality Association (WQA). This application includes the exact product configuration and a list of the materials of construction and the suppliers of those materials for any items designated as intended to come in contact with potable water.
The testing facility will review the materials of construction and chemical formulation, including any metals, coatings, elastomers, lubricants and seals that touch the water. If the manufacturer ever changes the build, such as replacing an elastomer with another vendor source, the product needs to be retested and recertified. This configuration-specific certification applies to all NSF components.
Extraction testing may be the step that is most familiar to operators and engineers. The product is exposed to controlled water conditions for a defined time period. The test is done under “worst-case” scenarios for temperature fluctuations and surface area exposure. The testing facility then examines the water bath for contaminants such as heavy metals (including lead and arsenic), volatile and semivolatile organic compounds (like benzene, vinyl chlorides, Bisphenol, etc.) and other regulated substances (disinfecting by-products, etc.). The list is extensive and these examples are illustrative, not exhaustive.
The product can be checked for pressure intensity, mechanical performance and operating durability conditions. This structural and performance evaluation is done to gauge if products could degrade and allow contamination to be introduced during operation.
The testing house next conducts audits of the manufacturing facility to check that materials being used to make NSF-certified components match what was submitted for testing.
The house checks that process and controls are in place, and the manufacturing is repeated in accordance with the submitted application. They also ensure the manufacturer has quality systems in place to prevent unauthorized changes, such as gaskets from a new vendor that would void the certification.
Once these steps are completed successfully, the product can be certified and will carry the certification mark from the testing house. That does not end the process, however, as there are ongoing audits of the certified product through factory check-ins, mandatory retesting periods and random quality sample checks.
What is Covered by Potable Water Safety from a Public Health Perspective?
- Microbicidal safety: No harmful bacteria, viruses, pathogens or parasites
- Chemical limits: Acceptable levels of metals, minerals and contaminants
- Physical quality: Turbidity, odor and clarity
In the U.S., potable water is regulated under the Safe Drinking Water Act (SDWA) and administered by the Environmental Protection Agency (EPA). SDWA was enacted in 1974 and amended in 1986 and 1996. Standards such as NSF 61 ensure equipment contacting water does not introduce contaminants.
Best Practices
These challenges are important to be aware of, but they are not insurmountable in creating an NSF-certified system.
- Systematic approach: When it comes to compliance, it is best to begin at the design stage and build compliance into the project’s DNA. Design engineers and purchasing/procurement teams should clearly lay out the need for NSF certification on all wetted components. Clear expectations reduce ambiguity and uncertainty in the system.
- Materials tracing/documentation: Set up documentation with verified components and registered certification status. Once established, follow rigorously and consistently. Knowing is always better than assuming.
- Verification and inspection: Routine checks help verify all is as it should be. Check that manufacturers keep the NSF on products, and that audits by the certify houses are done regularly. Just because a product has been certified does not mean it is currently certified. Verify before addition into your system.
- Standardization: The fewer differences there are across the system, the easier the task of source and verification will be.
- Training: Instruct operators on the importance of certification and what paperwork is necessary to ensure the wetted components comply.
On materials of construction, all NSF-certified components must be tested. Speaking from a pump perspective, stainless steel such as 304 or 316 is broadly used in food-grade and drinking water applications. Stainless steel’s corrosion resistance is a plus, but every alloy composition must pass certification requirements. Ductile iron, often with epoxy coatings, is used in municipal and agricultural settings and can be NSF certified. Bronze alloys may be used, but traditional leaded bronze is no longer compliant. With any material, it is best to check current regulations from NSF for guidance.
KEY CHALLENGES
Manufacturers control their products, but operators, design engineers and contractors control the whole system. The system must meet the NSF standard, including all materials and components, to provide the best outcome for end users. These issues may present challenges.
Manufacturer challenges
- Material compatibility: Items may perform well separately, but when combined, they can leach. That is why the testing houses require they undergo immersion and operational testing. This challenge is more than just on the manufacturer’s side, and it is addressed through the testing protocol.
- Component variability: Component changes, whether through the supply chain or otherwise, can impact compliance. If a single part changes, it must be resubmitted. The process takes time for the extraction testing, as well as structural performance, so it may be many months before the product is recertified. Recertification does not take place if the new part causes a failure to pass.
Operator challenges
- Legacy infrastructure: Certified components introduced into legacy systems may not be noncompliant. Aging systems may have higher allowable lead content or outdated coatings. These inconsistencies introduce uncertainty and present potential failure points.
- Full system: Another infrastructure issue can be introduced even on new systems. The NSF-certified component is certified only for itself. If any noncertified components are added to the system, it does not confer certification to those parts. If a pump is certified but is married to a noncertified valve or piping, the system would not be wholly NSF certified in that instance.
- Operation awareness: Lack of documentation and/or awareness can lead to the introduction of non-NSF parts into a system. Regulatory violations could ensue, along with costly remediation and reputational damage.
- Compliance: Systems are not only covered by NSF, but may also be covered by other regulatory statutes from cities, counties, states, etc. Operators should ensure they are in compliance with the most stringent standards.
In agriculture and wastewater, discussing emerging trends can sometimes be difficult. Differences in certification schemes and performance priorities need to merge with NSF standards to be fully compliant across the water stream.
Emerging Trends & Innovations
Science and regulator findings evolve, so the NSF standards are able to change. Recently, the tightening of lead content has caused retesting by many manufacturers. Contamination level detection has improved, allowing determinations at lower levels. More stringent requirements may be forthcoming with new science.
Digitization and AI analysis can help in component tracking, documentation, maintenance records and certifications. Internet of Things (IoT) monitoring can help with compliance assurance as well; parameters such as pH, conductivity, turbidity and contamination are easier to monitor and track than they were previously, allowing pump operators to address degradation earlier.
Materials advancement offers increases in durability as well as reduced environmental impact. Coating and polymers development has helped improve degradation resistance, which reduces leaching.
Water Reuse
NSF certification has long had a place in potable water. It is becoming increasingly important in industrial process, wastewater and irrigation. As these applications are all contributing at least peripherally to the system that potable water employs, their compliance is becoming increasingly important. Whether wastewater is being returned to the drinking water supply for reuse or being utilized in high-quality irrigation, the system demands will be different in five years than they are now—and they will be focused on cleaner, certified water throughout the process.
NSF certification is vital in ensuring safe, potable water, but it is not the only thing. Manufacturers’ attention to detail in materials and vendor components is a critical aspect. Along with good documentation, installation and training practices on the part of operators, this can help ensure better drinking water for all.
As the boundaries between water applications blur between reuse, integrated resource management and evolving regulations, manufacturers and operators will need to be more vigilant and aware in the future.
Ron Aceto is the municipal market manager for Cornell Pump. He has worked for more than 40 years in the pump industry and has extensive experience in the commercial, industrial and wastewater markets. For more information, visit cornellpump.com.
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