All water tanks intended to contain drinking water are required to include protective coatings and linings.
Forty eight states in the U.S. requires coatings and linings, either by law, regulation, or state policy, to comply with standards established by NSF International. The standards for all drinking water components, including drinking water storage tank liners and coatings, are contained in an industrial standard known as NSF 61 (also known as ANSI 61). Here are five facts about NSF 61 and what it means for tank owners and managers using NSF 61 certified containment products:
NSF 61 Standards Cover All Drinking Water Products
While drinking water tank coatings and linings are required to comply with NSF 61, the standard is broader than just containment products. In fact, NSF 61 covers all products within a drinking water system, including pipes, faucets, and joining and sealing materials.
Chemical Analysis of Containment Products
To apply for certification under NSF 61, a sample of the materials used to make the
containment products must be
analyzed to determine the entire formulation of the materials including any trace materials. The analysis must also include toxicology studies and extraction rates for chemicals in the materials. The analysis is submitted to the certifying agency along with an application for certification that describes how the containment product is manufactured and used.
Additional Testing of Containment Products
Depending on the materials used to produce the coatings and linings, additional
tests may need to be performed to determine whether the coating or lining contains specific toxic chemicals. For example, concrete water tank liners are tested using gas chromatography and mass spectrometry to determine the presence of doixins, glycols, radionuclides, and regulated metals like mercury and lead. This analysis is also submitted to the certifying agency with the application for certification.
The Plant is Inspected and Samples are Taken for Additional Testing
A plant audit is conducted by the certifying agency to ensure that the manufacturing practices and materials match up with the manufacturing processes and materials described in the application. Samples are also collected for additional testing by the certifying agency’s testing laboratory.
Tests Are Performed Over Time
Material testing by the certifying agency takes place over time to determine whether any chemicals will leach into water stored in the containment products. During this time, exposure water is repeatedly exposed to the containment product materials for varying time periods and tested for extracted chemicals.
In summary, containment products for drinking water, such as water storage tank liners, must meet certain requirements to satisfy NSF 61. The manufacturer must submit a material analysis including a toxicology report. The plant must be audited and additional samples taken for laboratory analysis by a certifying agency. Once the containment products are certified, the manufacturer is added to the NSF database and the manufacturer is allowed to promote the containment products as NSF certified.
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