The city of Rowlett, Texas, experienced an unauthorized wastewater...
Testing & certification options for commercial water treatment systems
Residential drinking water treatment unit products have many standards and protocols available to companies to demonstrate that their products have been tested and certified to verify that the materials that come into contact with drinking water are not harmful, the products are structurally sound and the performance reduction claims are accurate. Commercial products were seemingly left in the dust, however, and end users do not have a significant amount of guidance within the standards to make the same distinctions about these larger systems.
Rest assured — all hope is not lost for these types of products. Today, two standards exist in the U.S. that are widely used to demonstrate compliance to industry standards for commercial products. The first is NSF/ANSI 61, which is used to demonstrate that the materials with which the products are manufactured are not harmful. The second is NSF/ANSI 372. This standard focuses on the lead content within the materials with which the product is constructed.
Materials safety testing ensures that products are safe for contact with drinking water. NSF/ANSI 61 covers many types of products, including large systems that are used commercially. The process for the evaluation of material safety includes multiple steps.
To begin, the manufacturer creates a wetted parts list, which is a breakdown of the treatment system including each individual component that comes in contact with drinking water. Additionally, it contains pertinent information such as the materials each part is made from, where each component is made, and the wetted surface area of each component. The completed list is thoroughly reviewed by a toxicology team to determine the appropriate analytical test battery for the product.
The scope of the analytical test battery varies, but typically includes metals and organic testing of the water collected from the system during testing. Testing for leachable metals is conducted using two different pH exposure waters (pH 5 and pH 10) to ensure that metals do not leach from the product at unacceptable levels, regardless of the corrosivity of the water.
Testing for organic contaminants is conducted using pH 8 exposure water. Additionally, products containing adsorptive or absorptive media must be tested with and without the media. For extremely large systems that cannot feasibly be transported, samples of each material used to construct the end product may be exposed in-vessel at a surface area-to-volume ratio that represents the same ratio found in the end product.
The materials safety test consists of a conditioning period, followed by an exposure period during which samples are collected and analyzed to determine the concentrations of extractable contaminants. The manufacturer or supplier may choose the conditioning period for the product, which can be as short as one day and as long as 14 days. A 14-day conditioning period is most common, and requires at least 10 water changes (or fewer, if specified by the manufacturer) with a minimum of 24 hours of conditioning between changes. For example, a test system would be installed and flushed, filled with exposure water, held for 24 hours, then drained and refilled the next day. This procedure is repeated every day for two weeks, but the system could remain untouched for 72 hours over the weekend. After the 14th day of conditioning, the exposure period begins. At this point, the pH 8 exposure water used for organics extraction must be chlorine free for the exposure period.
All water evaluated for materials safety is compared to the Maximum Contaminant Levels and Maximum Allowable Concentrations for contaminants. In order for a product to meet the requirements of NSF/ANSI 61, the results from each type of exposure water must meet the requirements of the standard. The materials extraction test may seem tedious and over the top, but it helps to ensure that these products do not compromise public health and safety.
Low-lead evaluation and testing are the best ways to ensure that the materials used in the manufacture of products meet the federal lead law restricting the sale of plumbing products into commerce unless their lead content is at or below 0.25%. Under this standard, a wetted parts list including all the same details as for NSF/ANSI 61 is provided, however, it is not reviewed by a toxicologist to determine an analytical test battery. This standard is different in that the evaluation is the same regardless of the material type.
If required to undergo testing, the material will be evaluated to determine its percent lead content. The standard requires that the end product must not contain a total of 0.25% or more lead content after the weighted average lead content calculation has been completed. While this standard does not indicate whether a product will reduce the concentration of lead in water, it provides assurance that the materials with which it is constructed do not contain harmful amounts of lead.
Product testing demonstrates compliance to the testing protocols found in the standards. Certification goes a few steps further by teaming test data with annual audits of the facilities that manufacture the products to ensure that they are turning out products with the same specifications as those that have been tested. Product certification also monitors changes manufacturers make to the certified product. Material and supplier changes to previously tested products typically require additional testing to ensure that these products remain safe for contact with drinking water. While residential products have many other additional options for certification, commercial products are not left idle. Using certified products provides benefits over non-certified products.