BS-6920-1-1996.pdf

| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 6920 : Part 1 : 1996 ICS 13.060.20 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW 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 Part 1. Specification Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:30:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI This British Standard, having been prepared under the direction of the Health and Environment Sector Board, was published under the authority of the Standards Board and comes into effect on 15 December 1996 BSI 1996 First published May 1988 Second edition June 1990 Third edition December 1996 The following BSI references relate to the work on this standard: Committee reference EH/3/7 Draft for comment 95/521396 DC ISBN 0 580 26283 9 BS 6920 : Part 1 : 1996 Amendments issued since publication Amd. No.DateText affected Committees responsible for this British Standard The preparation of this British Standard was entrusted by Technical Committee EH/3, Water quality, to Subcommittee EH/3/7, Effects of materials on water quality, upon which the following bodies were represented: Association of Manufacturers of Domestic Electrical Appliances Automatic Vending Association of Britain British Adhesives and Sealants Association British Bathroom Council British Cement Association British Iron and Steel Producers' Association British Malleable Tube Fittings Association British Non-ferrous Metals Federation British Plastics Federation British Plumbing Fittings Manufacturers' Association British Rubber Manufacturers' Association Limited British Valve and Actuator Manufacturers' Association British Water Cadmium Association Department of the Environment (Drinking Water Inspectorate) Department of the Environment for Northern Ireland Department of Trade and Industry (Laboratory of the Government Chemist) Ductile Iron Producers' Association Galvanizers' Association Institute of Plumbing Lead Development Association Pipeline Industries Guild Pipeline Protection Association Scottish Association of Directors of Water and Sewerage Services UK Water Byelaws Scheme Water Research Centre Water Services Association of England and Wales Zinc Development Association Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:30:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6920 : Part 1 : 1996 BSI 1996i Contents Page Committees responsibleInside front cover Forewordii Specification Introduction1 1Scope1 2References1 3Definitions2 4Taste of water2 5Appearance of water2 6Growth of aquatic micro-organisms2 7The extraction of substances that may be of concern to public health2 8The extraction of metals3 9High temperature tests3 10Taste of water from hoses intended for food and drink application3 Table 1Maximum allowable concentrations of certain metals3 List of referencesInside back cover Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:30:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii BSI 1996 BS 6920 : Part 1 : 1996 Foreword This Part of BS 6920 has been prepared by Subcommittee EH/3/7 under the direction of the Health and Environment Sector Board. This Part of BS 6920 supersedes BS 6920 : Part 1 : 1990, which is withdrawn. This edition introduces technical changes, but it does not reflect a full review or revision of the standard, which will be undertaken in due course. Changes have been introduced to clauses 6 and 7 following revisions made to the respective sections of BS 6920. It is intended that appropriate British Standards and other specifications should cross-refer to this Part of BS 6920 if they specify requirements for the effects of the specified product on the quality of water for human consumption. BS 6920 is published in several Parts, namely Part 1 Specification, Part 2 Methods of test and Part 3 High temperature tests. Part 2 is further subdivided into a number of Sections and Subsections as follows: Section 2.1Samples for testing Section 2.2Taste of water Subsection 2.2.1General method of test Subsection 2.2.2Method of testing tastes imparted to water by hoses Subsection 2.2.3Method of testing tastes imparted to water by hoses for conveying water for food and drink preparation Section 2.3Appearance of water Section 2.4Growth of aquatic micro-organisms Section 2.5The extraction of substances that may be of concern to public health Section 2.6The extraction of metals Compliance with a British Standard does not of itself confer immunity from legal obligations. Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:30:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BSI 19961 BS 6920 : Part 1 : 1996 Specification Introduction The most common consumer complaint concerning the wholesomeness of drinking water is the presence of unacceptable taste and the role of construction and plumbing materials in giving rise to certain types of taste in water is well documented. Although the assessment of taste is subjective, semi-quantitative methods of assessing tastes in water have been used by the water industry for operational control and quality monitoring purposes for many years. The EC Directive relating to the quality of water intended for human consumption (80/778/EEC) 1 specifies for the first time a maximum admissible threshold level for taste in potable water, and this value is derived from the assessment by individuals of a series of successive dilutions of the water sample under examination. The criteria used to assess the ability of a product to support an appreciable growth of aquatic micro-organisms have been determined from a review of data obtained from the use of the method described in BS 6920 : Section 2.4 : 1988 during investigations into incidents of microbial contamination of potable water over a period of 10 years. When samples drawn from more than one commercial batch of a product are compared for the purpose of quality assurance or formulation development, some variation in the results should be anticipated. Any variation in results should be critically examined in light of the precision of the method and also the homogeneity of the material or the conditions employed during manufacture or storage, as these can substantially alter the characteristics of some products with respect to the availability of chemical substances that act as nutrients for microbial growth. The criteria given in clause 6 have been set in the light of the precision of the method, which was calculated on the basis of a homogeneous reference material. Careful consideration has been given to the desirability of some form of toxicological evaluation of extracts from products in contact with potable water. It has been concluded that some form of toxicological evaluation is essential, particularly in view of the paucity of toxicological data on many chemicals and the lack of knowledge of the chemical species which may be extracted from products in contact with potable water. Since there is no single test that can discriminate between harmless and harmful extracts, the cytotoxicity requirements given in clause 7 are meant only as a preliminary screening test for extracts from products in contact with potable water. Passing the tests indicates that extracts probably do not contain significant amounts of acutely toxic substances, but the tests cannot be used to indicate the presence or absence of substances that may be harmful on prolonged exposure. A failure in the tests indicates that the product requires further investigation before it can be accepted for use in contact with potable water. Clause 8 deals with the extraction of certain metals, undesirable in excessive amounts, from non-metallic products. The limits for these metals are given in table 1. The range of metals included in this specification reflects the current knowledge and experience of metals likely to arise in waters intended for human consumption, as a result of contact with the materials of construction of water storage and distribution systems. Products submitted for testing in accordance with BS 6920 in the future may contain other metals which may be undesirable in excessive amounts but which are not listed in table 1. In this case, it will be necessary to obtain an expert opinion from a competent national authority on the desirability of including its determination in this test. Clauses 9 and 10 deal with the specific requirements of products intended for use in contact with hot water intended for human consumption or culinary use, and of hoses intended for conveying water for food and drink preparation respectively. 1 Scope This Part of BS 6920 specifies requirements for the suitability of non-metallic products, including water fittings and components, pipes and materials used in coating, protection, lining, jointing, sealing and lubrication, for use in contact with either hot or cold water intended for human consumption, with regard to their effect on the quality of the water. 2 References 2.1 Normative references This Part of BS 6920 incorporates, by dated or undated reference, provisions from other publications. These normative references are made at the appropriate places in the text and the cited publications are listed on the inside back cover. For dated references, only the edition cited applies; any subsequent amendments to or revisions of the cited publication apply to this Part of BS 6920 only when incorporated in the reference by amendment or revision. For undated references, the latest edition of the cited publication applies, together with any amendments. 2.2 Informative references This Part of BS 6920 refers to other publications that provide information or guidance. Editions of these publications current at the time of issue of this standard are listed on the inside back cover, but reference should be made to the latest editions. Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:30:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 BSI 1996 BS 6920 : Part 1 : 1996 1) Hazen units 3 Definitions For the purposes of this Part of BS 6920, the following definitions apply. 3.1 water fitting Component associated with supply, distribution, and use of water, apart from its disposal. NOTE. This definition is taken from BS 6100 : Section 3.3. 3.2 product Manufactured item, in its finished form, that comes into contact with water, including a component part of a manufactured item. 4 Taste of water NOTE. See also paragraph one of the Introduction. When assessed by the method given in BS 6920 : Subsection 2.2.1, the product shall be deemed suitable for contact with water intended for human consumption if there is no discernible taste in the first dilutions of both the final unchlorinated and final chlorinated extracts. These taste requirements shall apply to hoses assessed in accordance with BS 6920 : Subsection 2.2.2. Hoses intended for conveying water for food and drink preparation shall also meet the additional requirements of clause 10 of this Part of BS 6920. The method yields results for the first and the final extracts in a sequential series of seven extractions. If the results from the first extract conform to these requirements, the first extract shall be defined as the final extract. If a discernible taste is detected by any taste panellist in the first dilution of the final (i.e. seventh) chlorinated or unchlorinated extracts, then the product shall be deemed unsuitable for contact with water intended for human consumption unless two further samples are assessed and the taste panellists report no taste in the first dilution of the final (i.e. seventh) chlorinated or unchlorinated extracts from both of the two further samples. If a discernible taste is detected by any taste panellist in the second dilution of the final (i.e. seventh) chlorinated or unchlorinated extracts, then the product shall be deemed unsuitable for contact with water intended for human consumption. 5 Appearance of water When assessed in accordance with BS 6920 : Section 2.3, the product shall be deemed suitable for contact with water intended for human consumption if the increase in colour and turbidity of the water in the final extract is not more than 5 standard units (of colour) mg/l Pt1)or 0.5 FNU, respectively. If a single sample does not conform to this requirement, then the product shall be deemed unsuitable for contact with water intended for human consumption unless two further samples are examined and the mean colour and turbidity of the final extracts of all the samples are not increased by more than 5 standard units (of colour) mg/l Pt1)or 0.5 FNU, respectively, after contact for 9 days (seven extractions). 6 Growth of aquatic micro-organisms NOTE. See also paragraphs two to four of the Introduction. When a product is examined by the method given in BS 6920 : Section 2.4, it shall be deemed not to support appreciable microbial growth if the mean dissolved oxygen difference (MDOD) is less than 2.4 mg/ml. If a single sample of a product gives an MDOD in the range 1.7 mg/l to 2.9 mg/l, then two further samples of the product shall be examined. If the arithmetic mean of the three MDOD values is lower than 2.4 mg/l, then the product shall be regarded as not being capable of supporting an appreciable microbial growth when in contact with water intended for human consumption. 7 The extraction of substances that may be of concern to public health NOTE 1. See also paragraphs five and six of the Introduction. There are no absolute criteria that can be applied to the results obtained with the methods given in BS 6920 : Section 2.5. In general, a product shall be regarded as being suitable for contact with water intended for human consumption if it exhibits a non-cytotoxic' response when assessed by the method given. NOTE 2. Assistance can be gained by reference to the parameters in annex 1 of the EC Directive relating to the quality of water for human consumption (80/778/EEC) 1, now incorporated into the Water Supply (Water Quality) Regulations 1989 2. Fittings in premises are considered by the Water Byelaws Scheme (Administered by the WRc Evaluation and Testing Centre). Materials used by water undertakers are covered by the following legislation. Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:30:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BSI 19963 BS 6920 : Part 1 : 1996 All water undertakers in England and Wales are subject to the requirements of the Water Supply (Water Quality) Regulations 1989 2, which came into force on 1 September 1989. Regulation 25 refers to the use of substances or products in the treatment and provision of water supplies. Essentially the regulation requires that a