The Increasing Role of UV in Swimming Pools and Spas
Monday, October 7, 2019
Most experts would agree that ultraviolet (UV) technology can play an important role in any commercial pool or spa.
UV has proven itself as an effective tool for sanitization when properly sized, operated and maintained. Specifically, the technology has demonstrated efficacy for inactivation of cryptosporidium, a microscopic parasite that is resistant to chlorine disinfection. This has increased the use of UV in commercial pools and spas.
Many sources address the importance of UV in pool applications, but none more important than the reference in the Model Aquatic Health Code (MAHC). The MAHC is a voluntary guidance document published by the Centers for Disease Control and Prevention (CDC) to help state and local government officials establish minimum safety requirements. The code stemmed from concerns about the increasing number of outbreaks starting in the mid-1990s. The goal of the MAHC is to apply the latest scientific knowledge and best practices in the pool industry to improve public safety.
The MAHC has long recognized the benefits of UV. In fact, the MAHC identifies UV as an appropriate technology for secondary disinfection. To be recognized as such, a system must achieve a minimum 3-log (99.9 percent) reduction in the number of infective cryptosporidium parvum oocysts in a single pass through the UV system. The MAHC states that “high-risk” venues, such as wading pools and therapy spas, must include a secondary disinfection system.
Validation of proper performance can be evaluated and certified by a third-party accredited body such as NSF International.
Under NSF/ANSI 50, UV systems can be evaluated for supplemental or secondary disinfection. While secondary disinfection must demonstrate a 3-log reduction of cryptosporidium, supplemental systems are evaluated for a minimum 3-log reduction of pseudomonas aeruginosa and enterococcus faecium. In both cases, NSF International evaluates a family of UV systems and chooses certain models for testing. Each selected model undergoes a sequence of standardized tests, all of which must meet the criteria in the standard.
Through this series of tests, NSF provides swimmers, operators and buyers confidence that a certified system has been proven to work. The standardized testing also creates a level playing field among UV manufacturers and different designs. Only those systems certified by NSF International to the requirements of NSF/ANSI 50 are authorized to bear the NSF mark.
In addition to product testing to NSF/ANSI 50, NSF also works with key stakeholders to develop sound evaluation processes for new and evolving technologies. UV generation is a tool that continues to evolve by demonstrating added benefits beyond sanitization. For example, this technology also has proven itself as an effective tool for chloramine reduction. Chloramines are formed when chlorine comes into contact with bather waste (typically perspiration, urine and oils) and are often the source of irritation for eyes, lungs and skin. At the time this article is being written, NSF/ANSI 50 does not include an evaluation process or pass/fail criteria for chloramine reduction. However, a component certification specification (CCS) was created to evaluate this and several other parameters aimed at improving the water quality in pools and spas. Under CCS-18325: Water Conditioning Devices for Recreational Water Facilities, NSF International issued its first certification of a UV system with a proven ability to reduce chloramines by a minimum of 25 percent. Through this reduction, swimming pool facilities large and small will create a more comfortable environment for bathers.