By Guy Franklin

Water intended for human consumption is treated to remove harmful substances and transmitted through pipes to the consumer. Once treated, the water is assumed by many customers to remain wholesome all the way to the tap. It’s obvious, however, this hasn’t always been the case. During the last century, both lead and coal tar pitch were used routinely in water distribution systems even though both are now known to be health hazards.

In order to stop inappropriate materials from being used in water distribution, many countries developed statutory requirements, approvals systems and tests to detect unsuitable materials. This article will describe the systems put in place for the approval of materials in the United Kingdom (UK), compare them with systems developed in other countries, and review the proposed European Acceptance Scheme (EAS).

The UK situation
In the UK, a two-tier approach exists. The lower tier, the Water Regulations Advisory Scheme (WRAS), applies to all water contact materials used in domestic and commercial plumbing systems. The higher tier, Secretary of State Approval, applies only to materials used in the water suppliers’ distribution systems that have a substantial surface area in contact with water.

The WRAS was created by UK’s water industry to ensure its compliance with the Water Supply (Water Fittings) Regulations of 1999, which replaced the Water Bylaws Scheme. These regulations require that no water fitting shall cause waste, misuse, undue consumption or contamination of water supplied by a water distributor.

To this end, a fitting is required to be of a certain quality and standard, and be suitable for the circumstances in which it’s used. The fitting is acceptable if it bears an appropriate CE marking in accordance with the European Constructive Directive (89/106/EEC) (CPD). A CE marking is a “passport” that allows manufacturers to freely distribute their products within the European marketplace; the letters CE are an abbreviation of the French phrase “Conformité Européene.” It conforms to an appropriate harmonized European Norm (EN), European Technical Approval (ETA), British Standard (BS), or some other national specification of a European Economic Area (EEA) State, which provides an equivalent level of protection and performance. In addition, it can also conform to a specification approved by the regulator.

At present, the EN and ETA options haven’t yet been developed for many product types. The WRAS, therefore, requires testing to the relevant British Standard, BS6920:2000 Parts 1-3, entitled, “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.” This standard has been developed to address water quality problems that would be, directly or indirectly, dangerous to human health. They are:

  1. Cytotoxicity (a measure of total toxicity),
  2. Extraction of metals,
  3. Growth of aquatic microorganisms, or
  4. Organoleptic tests (odor, taste, color and turbidity of water).

The tests have fixed pass criteria. Any product tested by a WRAS-approved laboratory and found to fulfill the criteria are then listed in the “Water Fittings and Materials Directory” for a period of five years, at the end of which re-testing will be requested for the listing to continue.

Regulation 25
Regulation 25 of The Water Supply (Water Quality) Regulations of 1989 introduced more stringent requirements for materials used in the water supply network. The scheme is administered by the Drinking Water Inspectorate (DWI), which provides guidance on the requirements for water contact materials. In the case of small surface area materials (e.g., pumps, valves and meters), WRAS approval is required. In the case of large surface area materials (e.g. pipes, tanks, reservoirs and linings), additional testing and Secretary of State Approval are required.

To gain Secretary of State Approval, an application must be made to an expert body—the Committee of Products and Processes for Use in the Public Water Supply (CPP). The group requires full formulation information, a satisfactory BS6920 test report, and instructions for use of the product. The CPP frequently requests further test information on the leaching of specific compounds, which may be of concern to public health from the material; the leaching of total organic carbons (TOC), and the leaching of unknown compounds detectable by gas chromatography-mass spectrometry (GC-MS) to BS6920:2001, Part 4. Bio-testing wasn’t carried out. Like the WRAS, the CPP has approved laboratories that can carry out this testing to their quality assurance requirements.

Once test results are submitted, the CPP will then either advise the product be approved by the Secretary of State, fail the product, or request further information. Products approved by the Secretary of State are listed on the DWI’s website: www.dwi.gov.uk

Comparison of other schemes
Many countries have their own approval processes. Most of them are a combination of the test requirements described here. A number of other tests, however, have been developed including an Ames test (a measure of total mutagenicity), chlorine demand, and foaming potential (normally included in organoleptic tests).

The test requirements in several countries are shown in Table 1 for comparison. Please note that these tests may not be required for all products.

The legal status of these approvals varies between countries. In the UK, only one body gives approvals; but, in France, three bodies exist that are permitted to carry out the test and give approvals. In Italy, manufacturers self certify—carry out the tests themselves—and make the results available for scrutiny via purchaser inspection. Often the test requirements regarding aspects of testing such as water type, material surface area to water volume, and quality assurance prevent mutual recognition of test results and approvals.

The future of regulations
Article 10 of the new European Drinking Water Directive (98/83/EC) requires that all new materials used in contact with drinking water don’t endanger human health. To this end, the European Acceptance Scheme (EAS) is being developed as part of the Construction Products Directive (89/106/EEC) (CPD). The intention is for EAS to replace approvals in individual member states, removing potential barriers to trade among states.

The following framework will soon be ready for the introduction of the EN to describe the test protocols. Where the product is novel, the European Organisa-tion for Technical Approvals (EOTA) will produce an ETA for that product, as well as a positive list of acceptable ingredients for use in the formulation of water contact materials; acceptance criteria and levels, and legal aspects of the EAS.

Testing requirements for the EAS haven’t been finalized; however, they will probably include:

  • Chlorine demand,
  • Cytotoxicity,
  • Enhancement of the growth of microorganisms,
  • Migration of specific chemicals identified from the formulation,
  • Migration of unknown chemicals,
  • Organoleptic tests (odor, flavor, color and turbidity), and
  • TOCs.

Conclusion
As part of the EAS, some products—which are unlikely to significantly affect water quality—will only be subjected to limited testing prior to approval. Implementation of the EAS is several years off. Member states, however, have been requested not to change their national approval systems to divert from the aims of the EAS.

About the author
Dr. Guy Franklin is business manager of the WRc-NSF materials testing laboratory based in the UK. His laboratory carries out testing accepted for WRAS, CPP, NSF, IAPMO, QAS and other approvals. He can be reached at +44 1491 636 550, +44 1491 636 501 (fax), email: [email protected] or website: www.wrcnsf.com

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