This article originally appeared in Water Quality Products magazine April 2020 issue as "Sum of all Parts"
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.
The Impact of Product End Use
In addition to water temperature, other criteria may be different between component and final product. The intended use of a product within the water system influences test protocol, normalization of test data to field conditions and even compliance criteria.
Products undergo both conditioning, a period during which water sits in contact with the product and is discarded and refilled for a prescribed number of hours or days and exposure, periods between 12 and 24 hours, when the final water sits in contact with the product before being collected for analysis. The conditioning period allows time for contaminants to seep out into water that will be discarded. Conditioning and exposure periods are determined by product end use, so a final product may require a different protocol than what was used for the certified parts. The most rigorous testing is typically associated with shorter conditioning periods and longer exposure periods. However, it is not always possible even for an experienced certifier to determine which protocol is worst case without conducting the testing, especially considering normalization to the specific field use.
Normalization is a calculation for adjusting laboratory results to concentrations that can be expected at-the-tap. Normalization calculations vary depending on where a product will be used, how many will be used, the volume of water the product will see in the field and if the water is static or flowing. For instance, a 0.5-inch valve evaluated for use anywhere within a residence—except in the last liter of plumbing—is considered an in-line mechanical device. The same 0.5-inch valve evaluated for use in the last liter of plumbing is considered a mechanical plumbing device or endpoint device. The standard has different normalization assumptions and calculations for in-line mechanical devices versus endpoint devices.
Furthermore, different end uses have different compliance criteria. In other words, the allowable concentration of a contaminant may be different. Let us go back to the 0.5-inch valve example. At-the-tap concentrations for an in-line mechanical device will be compared to total allowable concentrations (TAC). Whereas, at-the-tap concentrations for an end point device will be compared to single product allowable concentrations (SPAC); i.e. there is only a single faucet delivering water into your glass.
Take arsenic for example. The TAC for arsenic is 10 ppb. However, the SPAC for arsenic is only 1 ppb. The 0.5-inch valve could be noncompliant when used in combination with an endpoint device even if the valve is certified as an in-line mechanical device.
The use of components that have been certified individually is always a good place to start for manufacturers seeking certification of a final product or assembly constructed of multiple components, but it does not necessarily mean testing will be waived or the final product will prove to be compliant.
Most importantly, it does not mean that the final product can be considered certified and marketed as such without having been submitted to an ANSI-accredited certifier for evaluation, certification and listing. It is important to have a knowledgeable certifier evaluate all the complexities of the final product and its intended use in the water treatment or distribution system.
Purchasers and end users should look for the certifier’s mark on the product and check the certifier’s online listing to verify use ratings or restrictions. This information should be strictly followed so as not to void the certification and cause the product to perform differently in the field than expected from laboratory analyses.
Manufacturers should work with a third-party ANSI-accredited certifier like UL to evaluate and certify their products. A certifier can offer valuable assistance with selecting individual parts certified with use ratings that will make it possible to reduce testing or improve certification success. Following this guidance can help protect the manufacturer’s brand and ensure the health and safety of drinking water for years to come.