Richard a. Martin

Sometimes we may ask ourselves why we need regulations, standards or requirements. Take a moment to consider the state of society if there were no regulations: no traffic laws, no drinking water safety requirements, no pool or spa standards, etc. Without written rules, consistent enforcement or documented pathways for conflict resolution, life would be more chaotic than the Wild West. Regulations, standards, codes and protocols not only provide structure, documented rules and a means to assure products meet minimum performance requirements, but are needed to increase safety and reduce risk.

NSF International has developed standards and protocols for testing and certifying the performance and health effects of water treatment and distribution products for residential drinking water, industrial and wastewater, public/municipal drinking water and pool, spa and recreational water. Some of these standards also address UV water treatment systems:

  • NSF and EPA ETV Generic Protocol for the Development of Test/Quality Assurance Plans for Validation of UV Reactors
  • NSF/ANSI 50: Equipment for Pools, Spas, Hot Tubs, and Other Recreational Water Facilities
  • NSF/ANSI 55: Ultraviolet Microbiological Water Treatment Systems
  • NSF/ANSI 61: Drinking Water System Components –Health Effects

The ETV protocol and NSF/ANSI 50 are crucial building blocks that were recently harmonized to form more efficient testing and certification requirements for the drinking water and recreational water market. NSF/ANSI Standard 50 contains all-encompassing evaluation criteria for certifying products and materials used at recreational water facilities. It references the ETV protocol, which provides criteria to validate log inactivation of Cryptosporidium. NSF/ANSI Standard 55 is used to test and evaluate UV treatment systems for low flows, such as POU and residential POE products. NSF/ANSI Standard 61 is a material health-effects safety standard and does not contain functional performance or microbiological testing requirements. It is used to assess if drinking water products and materials have leachate contamination risks.

Related to drinking water, after the 1993 Milwaukee outbreak of Cryptosporidium, additional resources were deployed to investigate the causes of and treatment processes for waterborne cryptosporidiosis outbreaks. US EPA began a series of regulatory endeavors and proposed rules addressing Cryptosporidium. The most significant of these were the Information Collection Rule; the Interim Enhanced Surface Water Treatment Rule; the Long Term I Enhanced Surface Water Treatment Rule, Filter Backwash Rule and the Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR). In 1998, US EPA’s Environmental Technology Verification (ETV) program began a study to determine how well UV treatment would inactivate Cryptosporidium using new methods of animal infectivity to detect the kill or inactivation of Cryptosporidium. Working with the agency in May 1999, engineering firms and product manufacturers, NSF issued the final ETV report, which supported UV effectiveness in inactivating Cryptosporidium. The LT2ESWTR recognized the effectiveness of UV for the treatment of Cryptosporidium by including UV as part of the rule’s toolbox of treatment options.

In 2006, the US EPA Ultraviolet Disinfection Guidance Manual (USEPAUVDGM) was issued. It provides a documented set of examples and criteria to help cities and water utilities with site assessment, system design, installation, field testing and operation of UV systems. NSF worked with US EPA and state drinking water authorities to create an actionable set of testing criteria based on USEPAUVDGM. From this effort to add greater consistency and to better document the required quality assurance/ quality control procedures, NSF published the NSF and EPA ETV Generic Protocol for the Development of Test/Quality Assurance Plans for Validation of UV Reactors in 2009 (revised in 2011). The ETV UV protocol is based on and consistent with USEPAUVDGM.

Related to recreational water, NSF/ANSI Standard 50 sets criteria to assess the performance and functionality of many types of pool and spa equipment. It contains important design, performance and microbiological testing requirements for corrosion resistance, material health safety, burst-pressure tests, pressure-loss/head-loss tests, 3,000-hour-life testing, three-log bacterial disinfection efficacy tests using E. faecium and P. aeruginosa, operational protection, product marking and installation and use instructions. Newly popular spray parks and spray pads, however, were designed differently from pools and spas and were not held to the traditional pool and spa requirements. But, after many spray-park cryptosporidiosis outbreaks related to facilities not using NSF-certified UV systems, Understanding Testing and Certification of UV Systems for Recreational and Drinking Water Markets By Richard A. Martin Water Conditioning & Purification May 2013 new Cryptosporidium inactivation regulations were drafted in some states. To address the need for consistency, NSF initiated development of Cryptosporidium treatment requirements for recreational water UV systems in 2005. For the next few years, the NSF Joint Committee on Recreational Water Facilities worked with drinking water and recreational water stakeholders with the goal of creating harmonized Cryptosporidium criteria.

Regulations were eventually passed in California, Florida, New York, Texas and Utah to require UV systems that treat certain types of recreational water bodies (typically spray pads, spray grounds or wading pools) to be tested and certified to NSF/ANSI Standard 50 and to achieve a minimum three-log (99.9-percent) inactivation of Cryptosporidium. Some states have required NSF/ ANSI 50 certification and a delivered UV reduction equivalent dose of 40 mJ/cm2. These new UV Cryptosporidium criteria were added to the existing UV evaluation and testing requirements already in the standard. NSF/ANSI 50 requires a minimum of three-log Cryptosporidium inactivation performance (greater performance such as 40mJ/cm2 or four-log is also accepted) for UV system manufacturers that make product performance claims related to cyst inactivation. NSF issued the final harmonized, specific testing methods and evaluation criteria for third-party testing and certification of UV systems as part of NSF Standard 50 in 2010. NSF Standard 50 also cited the EPA ETV UV protocol and incorporated new evaluation and testing requirements that included a more specific and repeatable derivative of LT2ESWTR and UVDGM, as well as requirements from DVGW W-294 and ONORM 5873 (European criteria for UV system evaluation, testing and certification).

Due to this harmonized approach, UV systems may be easily evaluated for both drinking water and recreational market uses. The combined evaluation, testing (validation) and certification provide officials, facility operators and manufacturers the greatest benefit in reduced testing work and cost and the greatest acceptance. NSF certification for Cryptosporidium inactivation includes these important UV reactor validation steps:

  1. Obtain technical specifications for the system from the manufacturer
  2. Assess the UV sensors
  3. Perform collimated beam laboratory bench-scale testing
  4. Perform full-scale reactor testing
  5. Calculate the Reduction Equivalent Dose (RED)
  6. Adjust the RED for uncertainty in UV dose
  7. Calculate a validated dose for Cryptosporidium to show a minimum three-log reduction

The ETV protocol mandated the use of germicidal-only sensors, allowed DVGW or OONORM certified sensors, rejected duty sensors not within five percent of reference sensors, mandated radiometer agreement within five percent, required pipe configuration with a 90-degree bend for testing, specified conditions for performing organism stability testing and specified the minimum number of sensors for monochromatic and polychromatic lamps. The ETV protocol can be modified to address recent scientific advances and lessons learned by all stakeholders, including state regulatory agencies.

Other improvements resulting from ETV stakeholder reviews include precise timing of influent and effluent sample collection, a stakeholder procedure for allowing test organisms other than bacteriophage MS2, frequency of flowmeter calibration and frequency of reactor blanks. Certification is not based on a single test or validation, but requires initial testing and ongoing conformity assessment to ensure compliance with USEPAUVDGM and manufacturer claims of system performance. Unlike a validation (which is a one-time test report), certification also addresses production changes over time through annual onsite production audits of the entire UV system including the reactor, power supply and control system. Section 5.13 of USEPAUVDGM specifies components and parameters that require evaluation to determine the need for re-validation testing if they are changed or modified. Some examples of changes that might affect performance and hence require revalidation testing are:

  • Lamp type, gas mixture, power density, arc length, end reflectors, UV transmittance of the lamp envelope between 185-400 nm
  • Sleeve/shield thickness, material type and spectral absorbance
  • Sensor type, supplier, spectral response, location within reactor relative to lamps
  • Ballast operating voltage, current, frequency and waveform
  • Wetted geometry, reactor dimensions, design and hydraulics

NSF certification audits check for changes in these components. Manufacturers may submit changes for review. Changes may require no testing, minor testing or complete re-validation. Therefore, UV system certification provides much greater value to UV system users and purchasers than simple testing or validation alone. Certification also allows a company to control what proprietary information it releases and to whom. Certification requires limited public display of proprietary company information, while disclosing critical non-confidential details. A full validation (or test) report is developed under NSF certification but it is not placed in the public domain. Rather, the certified company can choose to provide the NSF validation report to the persons or organizations it desires.

About the author
Richard A. Martin B.Sc., AFO, CPO is the Senior Business Development Manager at NSF International in Ann Arbor, MI. He joined NSF in 1994 and has worked in and managed various segments of the NSF water business, including the plastics plumbing program, mechanical plumbing program, municipal drinking water systems program and the recreational water program. NSF-certified UV systems that comply with NSF/ANSI Standard 50 can be found on NSF’s listing web page: For further information, contact Martin at NSF International [email protected] or (734) 769-5346.




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