2.1 million residential inground swimming pools were built between 1991 and 2006. This achievement is monumental when contrasted with the preceding years. During this time, the annual new pools installed shot up from 97,000 to 176,000. In fact, the 2.1 million inground pools built during this period equaled the entire number of pools installed since the emergence of the U.S. market in the 50s.
Reflecting upon the latter half of the 20th Century, this information indicates substantial growth, but, when looking at the time since this inground installation boom, you can see a clear decline. In 2009, there were only 54,000 inground pools installed in the United States. The recession is largely to blame for this hit to the industry, but pool installations still have yet to return to their glory days.
Regardless, nearly 40 percent of all inground pools today were built between 1991 and 2006, placing a significance on the operation of existing pools. NSF/ANSI 50-2017: Equipment and Chemicals for Swimming Pools, Spas, Hot Tubs and Other Recreational Water Facilities covers materials, chemicals, components, products, equipment, and systems related to public and residential recreational water facility operation. This scope extends the standard’s applicability beyond just pools.
The NSF/ANSI 50-2017 standard document covers evaluation and testing guidelines for swimming pool treatment chemicals, filters, centrifugal pumps, non-integral strainers, valves, mechanical chemical feeding equipment, filtration media, UV light process equipment, automated controllers, heaters, flow metering devices, and numerous other components integral to the operation of recreational water facilities.
NSF/ANSI 50-2017, which was published in 2018, replaces the 2016 version of the same standard. If you’d like to learn about this past revision in depth, you can read our post on NSF/ANSI 50-2016a: Equipment for Swimming Pools, Spas, Hot Tubs and Other Recreational Water Facilities.
One of the obvious changes to this revision is with the title, as it now explicitly includes the chemicals related to recreational water facility operation. The scope has also been updated to reflect the inclusion of chemicals. Other than this update, NSF/ANSI 50-2017 underwent the following changes:
- Language for UV disinfection was aligned with that in the 2014 Model Aquatic Health Code (MAHC).
- Language for shelf life testing for manufacturers of water quality testing devices was revised.
- The water quality testing devices (WQTD) sections were updated.
- Flow meter language was revised to reflect consideration of the devices being used in applications where specific gravity is greater than 1.0.
- Normative references have been updated.
- Specific criteria for metal contaminant limits were added.
- Language adding clarity to effective size and uniformity coefficient calculations was incorporated.
- Language regarding chemical feeders was revised.
- Language regarding formulation testing in Annex A, “Materials review and qualification methods,” was revised.
- Exposure assumptions were updated in Annex R, “Toxicology review and evaluation procedures for swimming pool treatment chemicals.”
NSF/ANSI 50-2017: Equipment and Chemicals for Swimming Pools, Spas, Hot Tubs and Other Recreational Water Facilities is available on the ANSI Webstore.