By Rick Andrew
Water coolers as a product category have seen significant innovation over the last few decades. In part, this innovation is due to consumer trends. As consumer awareness about hydration has increased, so too has consumer focus on sustainability and the environment. These trends have helped to increase the market for POU water treatment in general, with one of the key categories being POU water coolers. Additional consumer trends, such as increased consumption of tea, have led to greater popularity of systems that deliver heated water in addition to cooled and/or room temperature water. Water coolers can be evaluated under a number of NSF/ANSI standards, depending on the configuration and features of the product. This column will explore these possibilities and discuss the various requirements associated with them.
Non-plumbed coolers
Non-plumbed coolers that are refilled manually, typically by the use of five- or three-gallon carboys, can be evaluated under NSF/ANSI 18 Manual food and beverage dispensing equipment. Note that this standard does not apply to vending machines of any kind, including the machines that vend drinking water and are frequently installed at supermarkets. NSF/ANSI 18 includes requirements for materials in contact with beverages, as well as requirements for design and construction. Materials requirements are based on conformance to NSF/ANSI 51 Food equipment materials. This standard is largely based on the requirements of the US Government in the form of Title 21, US Code of Federal Regulations, with additional requirements for metals, coatings and some other material types. Design and construction requirements are mainly focused on hygiene and the ability to effectively clean the system to prevent contamination.
One of the key requirements in NSF/ANSI 18 is an in-place cleaning test. This test involves contaminating the cooler with E. coli and then cleaning according to the manufacturer’s instructions. After cleaning, the cooler is refilled with sterile buffered dilution water. This water is then dispensed and analyzed for E. coli. The requirement is that the amount of E. coli must be reduced by 99.9999 percent (six-log) by the in-place cleaning procedure recommended by the manufacturer. Also, NSF/ANSI 18 requires that any water filters or reverse osmosis treatment must conform to the requirements of NSF/ANSI 42, NSF/ANSI 53 and/or NSF/ANSI 58, as applicable.
Plumbed-in coolers
Coolers that are connected to a pressurized potable water supply and do not need to be manually refilled can be evaluated under NSF/ANSI 61 Drinking water system components – Health effects. This standard addresses a broad scope of materials and components used in drinking water treatment and distribution, with the standard arranged in various sections by product type. For example, pipes and related products are addressed by Section 4, while joining and sealing materials are covered under Section 6. End-point devices typically installed in the last liter of the distribution system, such as water coolers, are handled in Section 9. This is also the section used for evaluating kitchen faucets. Note that the scope of NSF/ANSI 61 is health effects only. The standard addresses the safety of materials in contact with drinking water. It does not address structural integrity of pressure vessels, mechanical durability of valves or other types of performance criteria.
Safety of materials in contact with drinking water is established through extraction testing. The product is exposed to test water under specific conditions, after an initial conditioning period. Leaching of different types of contaminants is tested with exposure to water of varying pH and composition. Concentrations of any contaminants detected are normalized to the appropriate end use, and then evaluated to determine if they are at levels of toxicological significance. Also, POU products are excluded from the scope of NSF/ANSI 61. Standards for POU products (NSF/ANSI 42, NSF/ANSI 53 and NSF/ANSI 58) predate NSF/ANSI 61 and address safety of materials in contact with drinking water.
Coolers with POU treatment
POU treatment is addressed by the NSF/ANSI drinking water treatment units (DWTU) standards, a series of standards mainly arranged by the treatment technology and the contaminant reduction claims made by the manufacturer. Key among these when considering cooler applications are NSF/ANSI 42, NSF/ANSI 53, NSF/ANSI 55 and NSF/ANSI 58. Figure 1 describes the scope of each of these standards. They each address the safety of materials in contact with drinking water, structural integrity of components and systems connected to a pressurized water supply, contaminant reduction claims and user information. Material safety is evaluated through extraction testing, similar to the approach taken under NSF/ANSI 61. The test under the DWTU standards, however, is different in three important ways:
- Initial conditioning is according to the manufacturer’s instructions as opposed to a specific procedure detailed in the standard.
- Test water is different in terms of pH and composition.
- Normalization and end-use assumptions are different because they are for POU.
Structural integrity for systems connected to a pressurized water supply involves a hydrostatic test of 15 minutes at elevated pressure (most often 300 psi) and a cyclic test typically at 100,000 cycles of zero to 150 psi. Contaminant reduction tests vary according to the type of technology being evaluated and the claim(s) being made. Carbon filtration systems making claims of chemical reduction as tested under NSF/ANSI 42 and/or NSF/ANSI 53 are tested based on the manufacturer’s claimed treatment capacity. Aesthetic claims under NSF/ANSI 42 are tested to 100 percent of capacity, and health claims under NSF/ANSI 53 are tested to either 120 or 200 percent of capacity, depending on whether a volume-triggered filter change indicator is present.
Low-pressure mercury UV systems under NSF/ANSI 55 are tested either for disinfection as Class A systems, requiring a 40 mJ/cm2 dosage at the alarm set point at the highest achievable flowrate, or as Class B systems, requiring a 40 mJ/cm2 dosage at 70-percent UVT at the highest achievable flowrate. Note that Class A systems do require a UV sensor. RO systems are tested for TDS reduction and also for health claims, including reduction of heavy metals (such as copper, lead and pentavalent arsenic), over a seven-day test protocol described in detail in NSF/ANSI 58 and designed to evaluate a range of operating scenarios. Additionally, the daily production rate and efficiency of the system are established.
A variety of possibilities
Just as there are a number of possible configurations and features of water cooler systems, there are also a number of possible standards under which these products can be evaluated. Figure 2 provides a summary overview of these possible configurations and associated standards. The future may bring new consumer trends and additional product features. As that happens, these standards will be developed accordingly to continue to provide a scientifically sound basis for evaluation.
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: [email protected]