By Rick Andrew
Although there were previous regulations, requirements and testing of water supply fittings existing in the UK back to the 1980s, it was the UK water supply regulations of 1999 that gave rise to the scheme currently known as the Water Regulations Advisory Scheme (WRAS). These regulations state that “no water fitting shall be installed, connected, arranged, or used in such a manner that it causes or is likely to cause waste, misuse, undue consumption, erroneous measurement, or contamination of the water supply.” These five considerations drive the testing requirements that are the basis for WRAS. The first Water Regulations Guide describing WRAS was published in 2000 and the first online Water Fittings and Materials Directory was published in 2006.
WRAS itself represents more than 20 UK water companies or public water supply providers. This group coordinates consistent advice and interpretation of the regulations through its product approval process, promotes the regulations, offers advice to manufacturers and consumers and maintains a directory of approved products. Under the regulations, there is a legal duty on all users, owners or occupiers and anyone installing water systems, fittings or appliances to ensure compliance. Advance notice of proposed installations in specific cases must be provided, creating an environment in which architects, building developers and plumbers must follow these regulations on behalf of future owners or occupiers.
Looking at the specifics
Going back to the regulations, there are the five considerations regarding impact on the water supply:
• Undue consumption
• Erroneous measurement
The tests arising from these considerations can be grouped into two general categories: mechanical tests and material or hygienic tests.
Waste. Waste is essentially leakage of water. Tests to address waste include evaluations of mechanical strength through porosity and joint effectiveness and closure. There are also tests to assess endurance of operating mechanisms and thermal cycling resistance.
Misuse. Misuse includes inappropriate flows of cooling water and uses of water pressure for inappropriate purposes other than the purpose of delivering the water supply.
Undue consumption. Evaluations of toilet-flushing volume, amounts of water used in various cycles of appliance functioning, flowrates of faucets and water usage of washing machines are included under the scope of undue consumption.
Erroneous measurement. Accuracy of water meters is a key component of addressing the requirement to avoid erroneous measurement.
Material or hygienic tests
Contamination. Requirements to avoid contamination of the water supply include measures to prevent ingress of particles and also to prevent backflow. Also, the application of coatings is evaluated to assure that they are not contaminating the water supply. And the potential for corrosion or galvanic action is addressed due to the potential for contamination.
WRAS looks to conformance with British Standard (BS) 6920 as the remaining piece addressing prevention of contamination. The lengthy official title of BS 6920, Suitability of non-metallic products for use in contact with water intended for human consumption with regard to their effect on the quality of the water, aptly describes the scope and purpose of the standard. BS 6920 includes five main test requirements, applied to all non-metallic materials in contact with water:
• Odor and flavor
• Color and turbidity
• Extraction of metals
• Extraction of substances of concern to public health
• Growth of aquatic microorganisms
Each of these tests can be further characterized as follows:
Odor and flavor. This test is performed on individual materials to determine if the materials impart a discernable odor or flavor to the water. A taste-test panel is employed for the evaluation.
Color and turbidity. Evaluations are conducted on each material to determine whether they increase the color and/or turbidity of water to which they are exposed, using instrumental analysis methods.
Extraction of metals. A leaching test on all non-metallic materials is conducted. A set list of metals is analyzed regardless of material type or formulation. Metallic materials are not evaluated under this test.
Extraction of substances of concern to public health. This test is also known as the cytotoxicity test. Materials are exposed to water and then the water is placed in contact with mammalian cells to observe any toxic effects on the cells in order to assess potential human toxicity. This is a study of gross acute toxicity.
Growth of aquatic microorganisms. Materials are placed into water that is saturated with dissolved oxygen and sealed into bottles. Over a period of weeks, the dissolved oxygen levels are measured to determine if any microorganism growth has decreased the level of dissolved oxygen in the water.
Note that each of these tests is conducted on one material only, resulting in multiples of each test for products that include multiple non-metallic materials in contact with the water supply. Note also that no formulation disclosure is required because the testing is applied in the same way for each non-metallic material regardless of material type or formulation.
In contrast, the NSF/ANSI standards typically involve whole-product testing. The focus of the material safety test is on contaminant leaching. In order to accomplish the goal of very comprehensive testing, material formulations of each material in contact with drinking water are reviewed to develop a list of analyses the laboratory will conduct. Testing is very specific to materials used in the product and what contaminants might leach into the water. Further, any contaminants detected are evaluated for potential toxicity using toxicological assessment procedures included in the standards. Parameters such as odor and flavor and growth of aquatic microorganisms are not considered with respect to the NSF/ANSI standards.
WRAS approval includes submittal of product information and test results to demonstrate conformance to the WRAS requirements; the group itself does not own a testing laboratory. Mechanical test reports in accordance with WRAS requirements may be accepted from ISO 17025-accredited laboratories. Material test reports according to BS 6920 must be from laboratories listed on the group’s website (www.wras.co.uk). WRAS approves these laboratories based on their participation in comparison tests conducted to ensure that approved laboratories achieve similar test results.
Once information is submitted, it is reviewed by the Product Assessment Group (PAG), which meets about 20 times each year to review recently submitted WRAS approval applications and make a determination regarding acceptance. If an application is determined to be acceptable, then the approval is issued and added to the online Products and Materials Directory, https://www.wras.co.uk/approvals/; approvals are valid for five years. There are no manufacturing facility audits required for WRAS approvals, although products achieving approval are authorized to use the scheme’s approved certification mark.
Typical North American certifications, in contrast with WRAS approvals, do not use an assessment group or committee-type approach for determining conformance. Usually the process of the certification body directly assesses conformance and grants or denies certification. Also, these certifications require auditing of the manufacturing facility both initially and on an ongoing basis in addition to product documentation and testing as part of the overall certification.
About the author
Rick Andrew is NSF’s Director of Global Business Development–Water Systems. Previously, he served as General Manager of NSF’s Drinking Water Treatment Units (POU/POE), ERS (Protocols) and Biosafety Cabinetry Programs. Andrew has a Bachelor’s Degree in chemistry and an MBA from the University of Michigan. He can be reached at (800) NSF-MARK or email: [email protected]