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Controlling Contamination
in Drinking Water Treatment Chemicals NSF receives an occasional complaint about suspected contamination of NSF Certified drinking water treatment chemicals. Recently we became aware of contamination associated with the inadequate cleanout of common carriers.
NSF Certification policies require that Listed facilities use shipping containers that do not contribute contaminants to the product. Reused or recycled containers such as rail cars, tankers, drums or totes are required to be dedicated to one category of chemical for drinking water treatment-or the containers need to be adequately washed out and evidence of washout provided to the purchaser of the product upon request. A recent incident in Michigan involved contamination of a liquid alum shipment. The common carrier transporting the alum had a cleanout record. However, when the alum was transferred from the tanker, the in-line filters preceding the treatment plant's bulk tank became plugged with an organic residue, contaminating the liquid alum. Fortunately, the normalized concentration of organic contaminants in the alum did not exceed the requirements of NSF Standard 60 (1/10 th of the US EPA maximum contaminant levels). What is troubling about this case is that the common carrier had a valid cleanout record for the shipment. It is thought that the transfer lines, typically cleaned separately from the tankers, may have been the source of the contamination. Michigan Communities Meet to Discuss Potential Solutions NSF staff recently attended a meeting with water utility officials from six western Michigan communities. Representatives from a chemical manufacturer and a chemical repackager also participated. Of the six communities, three had known incidences of contamination in the past year. All three shipments used common carriers. At the meeting, proposed solutions to the contamination problem included requiring dedicated carriers in bid specs and chemical analyses of every shipment. Only a few water utilities and/or chemical suppliers, however, have the analytical instrumentation on-site to perform analyses, and eliminating common carriers would increase costs dramatically and reduce the number of suppliers. Standardized guidelines for cleaning practices and/or quality system registration of cleaning facilities are other potential solutions. Perhaps the best solution is to improve the education of chemical suppliers, carrier cleaning operations, and water utility staff to ensure that carriers are adequately cleaned. Chemical suppliers need to inspect every carrier carefully before loading drinking water treatment chemicals. Plant operators need to inspect product shipments and ask for evidence of cleanout. NSF Certification policies require that cleanout records be retained for every shipment by the suppliers and supplied to the water utilities. Suppliers also need to communicate the importance (and their potential liability) to the common carriers and the carrier cleaning facilities. |
The
NSF Certification of a drinking water treatment chemical applies to
the product as shipped, as long as it remains in the original shipping
container from the Listed facility. Once the package is opened, the
NSF Certification is void, based on the potential for contamination
or adulteration. For this reason, NSF certifies products at the manufacturing
site and repackaging sites, including terminals where chemicals are
transferred from one carrier to another.