April 6, 2020
Drinking water systems are made up of many different components, such as chemical generators, valves, pumps, booster pump systems, faucets and municipal and whole house water treatment devices, among others. These components of drinking water distribution and treatment systems are constructed with individual parts, such as single or multiple pumps and valves, gaskets, fittings, coatings, sealants, media and more that may be certified individually as stand-alone components for specific end uses within the water system. It is a common misconception that a final product can be considered certified as long as all of these individual parts, or most parts, are already certified. Marketing a final product that has not been certified on its own as being “made with certified components” does not meet the intent of the safety standards developed to protect human health and safety.
Some of the standards that regulators and consumers look to for assurance of drinking water safety and quality include NSF/ANSI 42, NSF/ANSI 44, NSF/ANSI 53, NSF/ANSI 55, NSF/ANSI 58 and NSF/ANSI/CAN 61, to name a few. Let us use NSF/ANSI/CAN 61 as an example. Most states in the U.S. require that municipal water treatment and distribution components be certified to this standard for Drinking Water System Components–Health Effects. This standard covers testing for contaminants or impurities imparted indirectly to drinking water by components and materials in contact with the water. In the laboratory, the products are submerged or filled with different pH waters, the water is left in contact with the product’s wetted materials for a prescribed amount of time, and then the water is collected and analyzed to determine what chemical compounds leached out. Every water contact surface must be taken into consideration as a whole. Multiple parts, even if certified individually, may each impart the same contaminants, and the sum total could exceed allowable levels.
The intended use of the final product within the system must be understood in order to accurately determine the level of impurities that will be imparted in the field, as compared to the test lab. The product may be intended for use at a treatment plant, in the distribution system (water mains), in the service lines (leading to residence), in the residence itself, for specialty uses, or even multiple intended uses. Where a final product is used matters, as it determines what water volume is involved and the concentration of impurities. A certified part or material used in the construction of a larger final product may have been certified using different water volume assumptions than what is required for the end use of the final system component.
For these reasons, a claim that a final product is “made with certified components” does not meet the criteria for final product certification. State and local water system administrators, manufacturers, distributors, and purchasers of drinking water contact products should be aware of this distinction and how to verify products certified to the specified safety and health standards.
Understanding NSF/ANSI/CAN 61 Criteria
This health effects standard is not simply a review of materials or ingredients to determine whether these may or may not be used. Instead, extraction testing and analytical data is used to determine compliance. The concentrations of chemical compounds that leach into the test water are compared to established drinking water contaminant limits.
A complete finished product is to be evaluated via laboratory testing, unless size, weight, volume, location and more make this impractical. This is to predict as closely as possible the total concentrations of contaminants that will leach into drinking water in the field. Further, components used in assembled products or devices may have undergone additional mechanical and/or chemical processing during the construction of the final device, which altered the water contact surface, changed the leaching characteristics or added unintended contaminants. For example, welding or brazing will not only affect the water contact surface of a component but also deposit additional materials that will need to be considered by the certifier and evaluated by test.
Health effects certifications are supplier and manufacturing location-specific because of the potential for contamination on the parts per billion level (think one droplet in 10,000 gallons) that cannot be perceived without testing and may pose a human health risk. It is not uncommon to detect contaminants from tools, cleaning fluids, processes such as abrasive blasting, or even packaging materials.
Another consideration is the temperature rating for certified components versus the temperature rating for the final product. As mentioned, testing involves submerging or filling the product with water. The temperature of the test water is dependent on the temperature of the water expected in the field. The majority of materials will leach contaminants in greater amounts when exposed to hot water compared to cold water. A component which has only been certified with a cold water rating should be expected to leach more contaminants when exposed to hot water, possibly at noncompliant levels in the finished device.
This article was originally published in WQP Magazine by our very own Amanda Dail, Staff Engineer, UL Water & Plumbing Systems. To read the full article, visit this link.