Guest Column - March 2004
Find a printable version here

Third-Party Certification of Water Circulation System Components

Pools & Spas

By Megan Cleary

Safely maintaining a public swimming pool or spa can be an overwhelming task for any pool operator or manager. Their attention must be split over many facets of the operation, including pool/spa/facility maintenance, budgeting costs, personnel training, accident prevention and water quality.

Water quality alone requires a multitude of tasks to maintain proper pH, disinfectant, turbidity and water levels, along with extensive record keeping. There is little time left for operators to worry about the inherent safety, performance and integrity of their circulation system equipment.

But they don't have to. Third-party certification of equipment to NSF/ANSI Standard 50, Circulation System Components and Related Materials for Swimming Pools, Spas/Hot Tubs is often required by state and local health codes for public pools and spas. This is because it assures the equipment's effective performance and safety. Since its inception in 1977, and through several revisions, NSF/ANSI Standard 50 has established the minimum requirements for materials, design and construction, and performance for equipment in the water circulation system of swimming pools and spas. This equipment includes filters, centrifugal pumps, recessed automatic surface skimmers, multiport valves, chemical feed equipment and process equipment, such as ozone, ultraviolet light or ion generators, as well as electrolytic chlorinators.

Public health officials and pool operators can rely on an independent assessment of a product's conformance to NSF/ANSI Standard 50 to provide peace of mind with regards to the safety and performance of the circulation system. As a result, facilities can be more efficient and safer for all bathers.

Third-party certification

NSF/ANSI Standard 50 is a voluntary standard written by a consensus of manufacturers, end users and regulatory officials. Because a third-party certifier, such as NSF International, serves all three of these industry branches, it provides an objective review of a product's safety and performance. An established and ANSI-accredited certification program will verify a product's conformance to NSF/ANSI Standard 50. The NSF certification process includes material review, product testing and production facility audits.

Once a manufacturer applies for certification, it submits technical information regarding its product, including materials/parts of construction, drawings, product instructions, intended uses for the product and manufacturer claims, that is, output capacity. This information is then used to determine the material reviews and testing necessary to verify the health effects and performance of the product per the requirements of NSF/ANSI Standard 50.

Testing health effects

Health effects are verified by a material review, whereby a toxicological review is completed for any material with greater than 200 square inches of wetted contact area. Per the requirements outlined in NSF/ANSI Standard 50, materials with less than 200 square inches of wetted area, or a mass less than 40 g (2 g for spa/hot-tub components), or those components made entirely from materials acceptable for use in accordance with 21 CFR 170-199 (Food and Drugs), are exempt from material review. Components made from materials that are acceptable for use in contact with potable water in accordance with NSF/ANSI 14, 51 or 61 are also exempt from review. Depending on the formulation information provided, extraction testing may be required to verify that no harmful levels of contaminants are leached out into the circulation system. The material reviews, and extraction testing if necessary, complete the health effects component of NSF/ANSI Standard 50.

Performance testing

The other component of Standard 50 addresses the product's performance. Depending on the product type, a battery of tests is conducted on a representative sample to verify that the product conforms to the requirements of the standard, as well as the manufacturer's claims. Chemical feeders, for example, require chemical resistance testing and uniformity (and repeatability) of output testing, while sand filters are tested for turbidity removal and cleaning efficiency, in addition to other tests for each product type.

Proper operation critical

The products are tested in accordance with the manufacturer's instructions and must be used this way in the field in order to maintain the certification. For example, when a flow-through chemical feeder manufacturer specifies a specific chemical (type, configuration and/or brand), the feeder will be tested using that specific chemical, and the use of anything other than their recommended chemical would void the certification in the field. This is for several reasons. Using one form of chlorine compound, such as Trichlor, with a feeder designed specifically for calcium hypochlorite could bring about an incompatibility situation resulting in fire, explosion and/or generation of poisonous gases. Also, the potential for inconsistency in chemical concentration resulting from using the incorrect chemical type, configuration or brand of chemical could result in inadequate or excessive chlorination, resulting in pool closure due to unsafe conditions.

Similarly, filters are tested at the manufacturer's recommended maximum flow rate and filter media, and if a certified filter is used in the field at a flow rate that exceeds the verified maximum, or uses an improper filter media, the certification becomes void. This is because filter operation at too high a flow rate or using the unspecified filter media for that unit could result in pool closure due to an unsafe condition. It is important to review a product's instructions and use the product accordingly, or an operator may find himself in violation of his state or local health code.

Product manual/data plate

Other requirements outlined in NSF/ANSI Standard 50 include the specific information that must be captured on the product's data plate and within the product manual. Depending on the product type, a data plate may need to include model/serial numbers, pressure requirements, a maximum flow rate and the maximum output (in the case of feeders or process equipment), as well as applicable warning or caution statements. Most of this information must also be captured in the product manual, in addition to installation and operation instructions, a parts replacement list, and a statement of manufacturer's warranty. The physical evaluation of a product conducted by NSF staff includes this extensive review of the data plate and product manual, assuring that pool operators will have all the necessary information to use a product safely and effectively.

Unannounced audits

Finally, once NSF certified, the manufacturer is subjected to annual monitoring to ensure that unauthorized changes aren't being made to a certified product. Unannounced audits are conducted annually at the final production facility, verifying that the materials of construction have not changed and that the design and performance of the product are not altered without prior authorization from NSF International. Quality control and product marking procedures are reviewed as well. If a manufacturer requests a change in a product, appropriate reviews of the change are completed, and retesting may be necessary, before the revised product is allowed to bear the certification mark.

Peace of mind

All these facets of third-party certification to NSF/ANSI Standard 50 come together to provide credibility to a manufacturer's product and peace of mind to pool operators. The internationally recognized NSF Mark on a product ensures confidence as far as the safety and performance of a product and increases product acceptance by public health officials. Most importantly, it allows pool operators to focus on all the other aspects of their facility operation, all the while providing a safer environment for swimmers.

Megan Cleary is business unit specialist for the Pool & Spa Equipment Program, NSF International in Ann Arbor, Mich. She can be reached at