Water, England And Wales Citation, commencement and interpretation 1 1 These Regulations may be cited as the Water Supply (Water Quality) (Amendment) Regulations 2018 and come into force on 11th July 2018. 2 In these Regulations, “the 2016 Regulations” means the Water Supply (Water Quality) Regulations 2016 . Amendment of the 2016 Regulations 2 1 The 2016 Regulations are amended as follows 2 In regulation 2 (interpretation)— a in paragraph (1)— i omit the definitions of “audit monitoring” and “check monitoring”; ii insert in the appropriate places— “ E. coli ” means Escherichia coli ; ; “monitoring of a Group A parameter” has the meaning given in regulation 5(1); “monitoring of a Group B parameter” has the meaning given in regulation 5(3); “monitoring programme” means a programme for the identification of, and collection of data on, any substance or organism identified during a risk assessment to confirm compliance with the prescribed concentrations set out in Schedule 1 which— consists of either or both of the following— collection and analysis of discrete water samples; measurements recorded by a continuous monitoring process, and may in addition consist of either or both of the following— inspections of records of the functionality, and maintenance status, of equipment; inspections of the catchment area, water abstraction, treatment, storage and distribution infrastructure; ; “suitably accredited body” means the Secretary of State or a person acting on behalf of the Secretary of State; ; b in paragraph (3)— i omit “, other than a structure at a treatment works”; ii after “stored for the” insert “sole”. 3 In regulation 4(1) (wholesomeness) after “Water supplied to premises” insert “that is intended for human consumption including”. 4 In regulation 5 (interpretation and application of Part 4)— a for paragraphs (1) to (3) substitute— 1 In this Part, “monitoring of a Group A parameter” means monitoring of a Group A parameter for the purpose of obtaining information at regular intervals— a as to the organoleptic and microbiological quality of water; b where relevant, as to the effectiveness of drinking water treatment, particularly for the purposes of disinfection, for the purposes referred to in paragraph (2); and c as regards indicator parameters, whether water supplied for regulation 4(1) purposes meets the specifications for those parameters. 2 A Group A parameter must be monitored to determine whether its presence in water supplied for regulation 4(1) purposes satisfies the provisions of Part 3 or, if a departure has been authorised under Part 7 in relation to that supply, the provisions of Part 3 as read with the terms of that departure. 3 In this Part, “monitoring of a Group B parameter” means monitoring of a Group B parameter for the purpose of obtaining information from which it may be established whether water supplied for regulation 4(1) purposes— a satisfies the provisions of Part 3 or, if a departure has been authorised under Part 7 in relation to that supply, the provisions of Part 3 as read with the terms of that departure; b meets the specifications for indicator parameters; c in respect of other parameters identified as relevant by the Secretary of State under regulation 9, meets the specifications for those parameters. ; b after paragraph (5) insert— 6 In this regulation— “Group A parameter” means a parameter specified in column 2 of Table 1 in Schedule 3; “Group B parameter” means a parameter specified in column 2 of Table 2 or, as the case may be, Table 3 in Schedule 3. . 5 In regulation 6 (monitoring: general provisions)— a for paragraph (3) substitute— 3 Except in a case to which paragraph (16) applies, the parameters listed in Tables A and B in Schedule 1 and the indicator parameters must be subject to— a monitoring of a Group A parameter if the parameter is one listed in column 2 of Table 1 in Schedule 3 and the circumstances specified in column 3 of that Table apply; b monitoring of a Group B parameter in any other case. ; b in paragraph (4)— i omit “Clostridium perfringens”; ii for “3, 10 and 11” substitute “9 and 10”; c for paragraph (5) substitute— 5 Compliance samples for chemical parameters including copper, lead and nickel must take the form of a random daytime sample of one litre volume taken at a consumer’s tap without prior flushing. ; d in paragraph (7), for “monitoring”, in the second place it appears, substitute “surveillance”; e in paragraph (15) for “2 and 3” substitute “8 to 13 (as applicable)”; f in paragraph (16)(a) for “48 hours after” substitute “at”. 6 In regulation 8(1) (authorisation of supply points) for “items 7 to 16 and 19 to 28 in column 1 of Table 3” substitute “item 6 in column 1 of Table 1, and as items 1 to 11 and 14 to 21 in column 1 of Table 3”. 7 For regulation 9 substitute— Number of samples 9 1 In each year a water undertaker must take or cause to be taken from its sampling points or, to the extent authorised under regulation 8, from its supply points, the standard number of samples for analysis of residual disinfectant and each parameter listed in— a column 2 of Table 1 in Schedule 3 (Group A parameters); b column 2 of Table 2 in Schedule 3 (Group B1 parameters); c column 2 of Table 3 in Schedule 3 (Group B2 parameters); d column 2 of Table 4 in Schedule 3 (Group A1 parameters); e column 2 of Table 5 in Schedule 3 (Group A2 parameters); f column 2 of Table 6 in Schedule 3 (Group A3 parameters); g column 2 of Table 7 in Schedule 3 (Group A4 parameters). 2 In respect of any parameter not referred to in paragraph (1), the Secretary of State may specify— a the number of samples which a water undertaker must take or cause to be taken from its sampling points in each year; b its prescribed concentration or value. 3 Samples required to be taken by this regulation must— a be taken at regular intervals; b in respect of sampling for chemical parameters in the distribution network other than sampling at a consumer’s tap, be taken and handled in accordance with international standard ISO 5667-5 entitled “ Water quality. Sampling. Guidance on treatment of drinking water from treatment works and piped distribution systems ” ; and c in respect of microbiological parameters in the distribution network and at a consumer’s tap, be taken and handled in accordance with European standard EN ISO 19458 entitled “Water Quality – Sampling for microbiological analysis” using sampling procedure A in the distribution network and sampling procedure B at a consumer’s tap. 4 Subject to paragraph (5), the Secretary of State may, in respect of any supplies of water by a water undertaker to a water supply zone, treatment works, supply points or a service reservoir, give the water undertaker written notice of any variation of— a the parameters subject to sampling (by the omission or addition of parameters); b the number of samples which the undertaker must take in the period specified in the notice. 5 Paragraph (4) does not apply in relation to E. coli . 6 The Secretary of State may give a notice under paragraph (4)— a on the Secretary of State’s own motion; or b where paragraph (8) applies, upon application by a water undertaker. 7 A notice under paragraph (4)— a must specify which parameters are subject to a variation; b must specify the extent of any variation from the standard number of samples required to be taken under paragraph (1) or from the number of samples required to be taken under paragraph (2); c may require a risk assessment to be undertaken; d may be revoked or varied by the Secretary of State. 8 This paragraph applies where— a a risk assessment complying with this regulation has been undertaken and indicates that no factor can be reasonably anticipated to be likely to cause deterioration of the quality of the water; b in the case where the water undertaker seeks to cease monitoring a particular parameter, the results from samples taken in respect of the parameter collected at regular intervals over a period of at least three years are all at less than 30% of the parametric value of the parameter; and c in the case where the water undertaker seeks to reduce the frequency of monitoring in respect of a particular parameter, the results from samples taken in respect of that parameter collected at regular intervals over a period of at least three years are all at less than 60% of the parametric value of the parameter. 9 The Secretary of State must by further written notice withdraw a notice given under paragraph (4) if the Secretary of State believes that any parameter in the water supply to which the notice relates contravenes the prescribed concentration or value or is likely to do so. 10 A water undertaker given a notice under paragraph (4) must institute a monitoring programme which must be kept under annual review. 11 A risk assessment complies with this regulation where— a it meets the principles of European Standard EN 15975-2 entitled “Security of drinking water supply – Guidance for risk and crisis management – Part 2: Risk management” or of other equivalent standards accepted at international level; b it is subject to a system of quality control which is checked from time to time by a suitably accredited body; and c it takes into account the results of monitoring conducted under the second paragraph of Article 7(1) and Article 8 of Directive 2000/60/EC of the European Parliament and of the Council establishing a framework for Community action in the field of water policy . 12 In this regulation “the standard number” means the number of samples specified in Part 2 or Part 3 of Schedule 3 in respect of a parameter specified in Part 1 of that Schedule. . 8 Omit regulation 11. 9 In regulation 13 (sampling at treatment works)— a in paragraph (1) for “paragraphs (2), (4) and (6)” substitute “paragraph (6)”; b omit paragraphs (2) to (4); c in paragraph (6) for “the reduced number” substitute “the number specified in a current notice given by the Secretary of State under regulation 9 which departs from the standard number”; d after paragraph (6) insert— 7 In this regulation, “the standard number” has the same meaning as in regulation 9 . 10 In regulation 14 (sampling at service reservoirs) after “in use” insert “or as specified in a notice given by the Secretary of State under regulation 9(3)”. 11 For regulation 16 substitute— Collection and analysis of samples 16 1 Every water undertaker or wholesale licensee must secure, so far as reasonably practicable, that when it takes, handles, transports, stores or analyses any sample required to be taken for the purposes of Part 4 or this Part, or causes any such sample to be taken, handled, transported, stored or analysed, it complies with the appropriate requirements. 2 Every water undertaker or wholesale licensee must secure that a suitably accredited body checks from time to time its compliance with the appropriate requirements. 3 Additionally, any person involved in seeking to discharge the obligation described in paragraph (1) must ensure that— a the methods of analysis used by that person for the purposes of monitoring and demonstrating compliance with this Part are validated and documented in accordance with European standard EN ISO/ IEC 17025 entitled “ General requirements for the competence of testing and calibration laboratories ” or other equivalent standards accepted at international level; and b that person applies quality management system practices in accordance with European standard EN ISO/IEC 17025 or other equivalent standards accepted at international level. 4 Every water undertaker or wholesale licensee must maintain such records as are sufficient to enable it to establish, in relation to each sample taken for the purposes of Part 4 or this Part, that such of the appropriate requirements as are applicable to that sample have been satisfied. 5 Subject to paragraph (6), for the purpose of establishing, within acceptable limits of deviation and detection, whether the sample contains concentrations or values which contravene the prescribed concentrations or values, or exceed the specifications for indicator parameters— a the method of analysis specified in column 2 of Table A1 in Schedule 5 must be used for the parameter specified in relation to that method in column 1; b the method of analysis in respect of the parameters listed in column 1 of Table A3 in Schedule 5 must be capable of measuring concentrations equal to the parametric value with a limit of quantification of 30% or less and an uncertainty of measurement as specified in column 2 of that Table and the result must be expressed— i using at least the same number of significant figures as the parametric value, and ii in the same units laid down in these Regulations; and c the method of analysis used for the odour and taste parameters (items 5 and 7 in Part 2 of Table B in Schedule 1) must be capable, at the time of use, of measuring values equal to the parametric value with a precision or uncertainty of measurement of 1 dilution number at 25°C. 6 The Secretary of State may, on the application of any person, authorise a method of analysis other than that specified in paragraph (5)(a) (“the prescribed method”). 7 An application for the purposes of paragraph (6) must be made in writing and must be accompanied by— a a description of the method of analysis; and b the results of the tests carried out to demonstrate the reliability of that method and its equivalence to the prescribed method. 8 But the Secretary of State must not authorise the use of the method proposed in the application unless the Secretary of State is satisfied that the results obtained by the use of that method are at least as reliable as those produced by the use of the prescribed method. 9 An authorisation under paragraph (6) may be subject to such conditions as the Secretary of State considers appropriate. 10 The Secretary of State may at any time, by notice in writing served on the water undertaker or wholesale licensee to which an authorisation under paragraph (6) has been given, revoke the authorisation, but any such notice must be served no later than 3 months before the date on which the revocation is stated to take effect. 11 In this regulation, “appropriate requirements” means such of the following requirements as are applicable— a the sample is representative of the quality of the water at the time of sampling; b the person taking the sample is doing so in accordance with a system of quality control to an appropriate standard; c the sample is not contaminated in the course of being taken; d the sample is kept at such a temperature and in such conditions as will secure that there is no material alteration of the concentration or value for the measurement or observation of which the sample is intended; e the sample is analysed, whether at the time and place it is taken or as soon as reasonably practicable after it is taken— i by or under the supervision of a person who is competent to perform that task; and ii with the use of such equipment as is suitable for the purpose . 12 In regulation 34 (maintenance of records) in paragraphs (1)(h) and (2)(ca) omit “made”. 13 For Schedule 3, substitute— SCHEDULE 3 Monitoring Regulation 6 PART 1 Group A and Group B parameters Table 1 Group A parameters and circumstances for monitoring (1) Item number (2) Parameter (3) Circumstances (1) Sampling for this parameter in water supply zones may be substituted by sampling at supply points. 1 Aluminium Where used as a water treatment chemical or where the water originates from, or is influenced by, surface waters 2 Ammonium Where chloramination is practised 3 Coliform bacteria In all circumstances 4 Colony counts 22°C In all circumstances 5 Colour In all circumstances 6 Conductivity In all circumstances 7 E. coli In all circumstances 8 Hydrogen ion In all circumstances 9 Iron Where used as a water treatment chemical or where the water originates from, or is influenced by, surface waters 10 Manganese Where the water originates from, or is influenced by, surface waters 11 Nitrate Where chloramination is practised 12 Nitrite Where chloramination is practised 13 Odour In all circumstances 14 Residual disinfectant In all circumstances 15 Taste In all circumstances 16 Turbidity In all circumstances Table 2 Group B1 parameters and circumstances for monitoring to be used for sampling in water supply zones (or supply points) (1) Item number (2) Parameter (3) Circumstances (1) Sampling for these parameters may be within water supply zones (Group B1) or at supply points (Group B2). (2) Monitoring of this parameter in water supply zones is required only where sodium hypochlorite is added after water has left the treatment works. In other circumstances, monitoring is required at supply points (see Group B2). (3) To monitor for indicative dose. (4) In the event that a single sample is taken in a year, a further sample must be taken if there is any change in relation to that supply that could affect the concentration of radionuclides in the water supply. 1 Aluminium Where not used as a water treatment chemical or where the water neither originates from, nor is influenced by, surface waters 2 Ammonium Where chloramination is not practised 3 Antimony In all circumstances 4 Arsenic In all circumstances 5 Benzene In all circumstances 6 Benzo(a)pyrene In all circumstances 7 Boron In all circumstances 8 Bromate In all circumstances 9 Cadmium In all circumstances 10 Chloride In all circumstances 11 Chromium In all circumstances 12 Clostridium perfringens (including spores) In all circumstances 13 Copper In all circumstances 14 Cyanide In all circumstances 15 1, 2 dichloroethane In all circumstances 16 Enterococci In all circumstances 17 Fluoride In all circumstances 18 Gross alpha In all circumstances 19 Gross beta In all circumstances 20 Iron Where not used as a water treatment chemical or where the water neither originates from, nor is influenced by, surface waters 21 Lead In all circumstances 22 Manganese Where the water neither originates from, nor is influenced by, surface waters. 23 Mercury In all circumstances 24 Nickel In all circumstances 25 Nitrate Where chloramination is not practised 26 Nitrite Where chloramination is not practised 27 Pesticides and related products In all circumstances 28 Polycyclic aromatic hydrocarbon In all circumstances 29 Radon In all circumstances 30 Selenium In all circumstances 31 Sodium In all circumstances 32 Sulphate In all circumstances 33 Tetrachloroethene In all circumstances 34 Tetrachloromethane In all circumstances 35 Total organic carbon In all circumstances 36 Trichloroethene In all circumstances 37 Trihalomethanes: Total In all circumstances 38 Tritium In all circumstances Table 3 Group B2 parameters and circumstances for monitoring to be used for sampling at works or supply points (1) Item number (2) Parameter (3) Circumstances (1) Sampling for these parameters may be within water supply zones (Group B1) or at supply points (Group B2). (2) Monitoring is required at supply points where sodium hypochlorite is not added after water has left the treatment works. In other circumstances, see Group B1. (3) To monitor for indicative dose. (4) In the event that a single sample is taken in a year, a further sample must be taken if there is any change in relation to that supply that could affect the concentration of radionuclides in the water supply. 1 Benzene In all circumstances 2 Boron In all circumstances 3 Bromate In all circumstances 4 Chloride In all circumstances 5 Clostridium perfringens (including spores) In all circumstances 6 Cyanide In all circumstances 7 1, 2 dichloroethane In all circumstances 8 Fluoride In all circumstances 9 Gross alpha In all circumstances 10 Gross beta In all circumstances 11 Indicative dose In all circumstances 12 Mercury In all circumstances 13 Nitrite When chloramination is not practised 14 Pesticides and related products In all circumstances 15 Radon In all circumstances 16 Sulphate In all circumstances 17 Tetrachloroethene In all circumstances 18 Tetrachloromethane In all circumstances 19 Total organic carbon In all circumstances 20 Trichloroethene In all circumstances 21 Tritium In all circumstances Table 4 Group A1 parameters (1) Item number (2) Parameter 1 Coliform bacteria 2 E. coli 3 Residual disinfectant Table 5 Group A2 parameters (1) Item number (2) Parameter 1 Coliform bacteria 2 Colony counts 22°C 3 E. coli 4 Nitrite 5 Residual disinfectant 6 Turbidity Table 6 Group A3 parameters (1) Item number (2) Parameter 1 Conductivity Table 7 Group A4 parameters (1) Item number (2) Parameter 1 Aluminium 2 Ammonium 3 Colony counts 22°C 4 Colour 5 Conductivity 6 Hydrogen ion 7 Iron 8 Manganese 9 Nitrate 10 Nitrite 11 Odour 12 Taste 13 Turbidity PART 2 Annual sampling frequencies: water supply zones Annual sampling frequencies for Group A4 parameters: water supply zones This table and each table which follows it in this Part set out the annual sampling frequencies for all the substances and parameters comprising each of the groups to which they correspond, those groups having been outlined in Part 1 of this Schedule. These are determined for each water supply zone according to its estimated population (as specified in column 1 of each table in this Part). The number of samples to be taken is the standard number specified in column 2, unless a notice varying this number has been given under regulation 9. For the purposes of this table, where the population is not an exact multiple of 5,000, the population figure must be rounded up to the nearest multiple of 5,000. Table 8 Annual sampling frequencies for Group A4 parameters: water supply zones (1) Estimated population of water supply zone (2) Standard sampling frequency per year <100 2 100-4,999 4 5,000-9,999 12 10,000-29,999 24 30,000-49,999 36 50,000-79,999 52 80,000-100,000 76 Table 9 Annual sampling frequencies for Group B1 parameters: water supply zones (1) Estimated population of water supply zone (2) Standard sampling frequency per year <100 1 100-4,999 4 5000-100,000 8 Table 10 Annual sampling frequencies for Group A1: water supply zones (1) Estimated population of water supply zone (2) Standard sampling frequency per year <100 4 ≥100 12 per 5,000 population For the purposes of this table, where the population is not an exact multiple of 5,000, the population figure must be rounded up to the nearest multiple of 5,000. PART 3 Annual sampling frequencies: treatment works and supply points Annual sampling frequencies for Group A2 parameters: treatment works or supply points This table and each table which follows it in this Part set out the annual sampling frequencies for all the substances and parameters comprising each of the groups to which they correspond at treatment works or supply points, those groups having been outlined in Part 1 of this Schedule. The frequencies are determined according to the volume of water supplied at each treatment works or supply point. The number of samples to be taken is the standard number specified in column 2, unless a notice varying this number has been given under regulation 9. Table 11 (1) Volume of water supplied m 3 /day (2) Standard sampling frequency per year <20 4 20-1,999 12 2,000-5,999 104 6,000-11,999 208 ≥12,000 365 Table 12 Annual sampling frequencies for Group A3 parameters: supply points (1) Volume of water supplied m 3 /day (2) Standard sampling frequency per year <20 2 20-999 4 1,000-1999 12 2,000-5,999 24 6,000-9,999 36 10,000-15,999 52 16,000-32,999 104 33,000-49,999 156 50,000-67,999 208 68,000-84,999 260 85,000-101,999 312 102,000-119,999 365 120,000-241,999 730 242,000-484,999 1,460 485,000-728,999 2,190 Table 13 Annual sampling frequencies for Group B2 parameters: treatment works or supply points (1) Volume of water supplied m 3 /day (2) Standard sampling frequency per year <20 1 20-999 4 1,000-49,999 8 50,000-89,999 12 90,000-299,999 24 300,000-649,999 36 ≥650,000 48 14 In Schedule 4 (monitoring for indicative dose and analytical performance characteristics)— a in paragraph 4(1) (calculation of the ID), for paragraph (a) substitute— a the measured radionuclide concentrations and the dose coefficients referred to as “standard values and relationships” in Article 13, and recommended for the estimation of doses from internal exposure in the definition of “standard values and relationships” in Article 4(96), of Council Directive 2013/59/Euratom laying down basic safety standards for protection against the dangers arising from exposure to ionising radiation , or ; b in the text immediately following the title to Table 1, for the words from “laid down” to “96/29/Euratom” substitute “referred to as “standard values and relationships” in Article 13, and recommended for the estimation of doses from internal exposure in the definition of “standard values and relationships” in Article 4(96), of Council Directive 2013/59/Euratom”. 15 In Schedule 5 (analytical methodology)— a for Table A1, substitute— Table A1 Microbiological parameters for which, subject to regulation 16(6), methods of analysis are specified (1) Parameter (2) Method of analysis E. coli and coliform bacteria EN ISO 9308-1 or EN ISO 9308-2 Enterococci EN ISO 7899-2 Pseudomonas aeruginosa EN ISO 16266 Enumeration of culturable microorganisms – colony count 22°c EN ISO 6222 Enumeration of culturable microorganisms – colony count 36°c EN ISO 6222 Clostridium perfringens (including spores) EN ISO 14189 ; b omit Table A2; c at the end insert— Table A3 Minimum performance characteristic uncertainty of measurement The uncertainty of measurement laid down in this table must not be used as an additional tolerance to the parmetric value set out in Schedules 1 and 2. (1) Parameters (2) Uncertainty of measurement % of the parametric value (except for pH) (1) “Uncertainty of measurement” is a non-negative parameter characterising the dispersion of the quantity values being attributed to a measurement, based on the information used. The performance criterion for measurement uncertainty (k = 2) is at least the percentage of the parametric value stated in the table. (2) If the value of uncertainty of measurement cannot be met, the best available technique must be selected (up to 60% of the parametric value). (3) The method determines total cyanide in all forms. (4) Reference method: European standard EN ISO 8467 entitled “Water quality – Determination of permanganate index (ISO 8467)” . (5) The performance characteristics for individual pesticides are given as an indication. Values for the uncertainty of measurement as low as 30% can be achieved for several pesticides, higher values up to 80 % may be allowed for a number of pesticides. (6) The performance characteristics apply to individual substances, specified at 25% of the parametric value in Part I of Table B in Schedule 1. (7) The performance characteristics apply to individual substances, specified at 50% of the parametric value in Part I of Table B in Schedule 1. (8) The uncertainty of measurement must be estimated at the level of 3 mg/l of the total organic carbon (TOC) in accordance with European standard EN 1484 entitled “Water analysis – Guidelines for the determination of total organic carbon and dissolved organic carbon” . (9) The uncertainty of measurement must be estimated at the level of 1.0 nephelometric turbidity units) in accordance with European standard EN ISO 7027-1 entitled “Water quality – Determination of turbidity – Part 1: Quantitative methods (ISO 7027-1” . Aluminium 25 Ammonium 40 Antimony 40 Arsenic 30 Benzene 40 Benzo(a)pyrene 50 Boron 25 Bromate 40 Cadmium 25 Chloride 15 Chromium 30 Colour 20 Conductivity 20 Copper 25 Cyanide 30 1,2-dichloroethane 40 Fluoride 20 Hydrogen ion concentration pH (expressed in pH units) 0.2 Iron 30 Lead 25 Manganese 30 Mercury 30 Nickel 25 Nitrate 15 Nitrite 20 Oxidisability 50 Pesticides 30 Polycyclic aromatic hydrocarbons 50 Selenium 40 Sodium 15 Sulphate 15 Tetrachloroethene 30 Tetrachloromethane 30 Trichloroethene 40 Trihalomethanes: total 40 Total organic carbon 30 Turbidity 30 . Transitional and saving provisions 3 1 Despite regulation 2(11) and (15), the following provisions of the 2016 Regulations as in force immediately before 11th July 2018 remain in force in the transitional period with the modifications to those provisions in paragraph (2) and for the purposes set out in paragraph (3)— a regulation 16(5) and (6); b Table A2 in Schedule 5. 2 The modifications are that— a regulation 16(5) is to be read as if— i “Subject to paragraph (7),” were omitted; ii sub-paragraph (a) were omitted; iii in sub-paragraph (b), for “that Schedule” there were substituted “Schedule 5”; b regulation 16(6) is to be read as if for “limit of detection” to the end there were substituted— “limit of detection” is to be calculated as— three times the standard deviation within a batch of a natural sample containing a low concentration of the parameter; or five times the standard deviation within a batch of a blank sample; “precision” is to be calculated as a measure of random error and may be expressed as the standard deviation (within and between batches) of the spread of results from the mean. A precision measurement of twice the relative standard deviation is acceptable. The term “precision” is further specified in international standard ISO 5725 entitled “Accuracy (trueness and precision) of measurement methods and results” , as amended by the technical corrigendum entitled “Accuracy (trueness and precision) of measurement methods and results - Part 1: General Principles and Definitions TECHNICAL CORRIGENDUM 1” ; “trueness” is to be calculated as a measure of systematic error which is the difference between the mean value of the large number of repeated measurements and the true value. This term “trueness” is further specified in international standard ISO 5725 entitled “Accuracy (trueness and precision) of measurement methods and results”, as amended by the technical corrigendum entitled “Accuracy (trueness and precision) of measurement methods and results - Part 1: General Principles and Definitions TECHNICAL CORRIGENDUM 1”. ; c in Table A2, the entry in column 4 (limit of detection) which relates to 1,2-dichloroethane is to be read as if for “25” there were substituted “10”. 3 For the whole of the transitional period or any part of it beginning with 11th July 2018, a water undertaker or wholesale licensee may, in respect of any parameter specified in column 1 of Table A2 in Schedule 5 to the 2016 Regulations, elect to be subject to the saved provisions instead of regulation 16(5)(b) of, and Table A3 in Schedule 5 to, those Regulations as inserted by regulation 2(11) and (15)(c) respectively of these Regulations. 4 In this regulation— “saved provisions” means the provisions saved by paragraph (1) as modified by paragraph (2); “transitional period” means the period beginning with 11th July 2018 and ending with 31st December 2019. David Rutley Parliamentary Under Secretary of State Department for Environment, Food and Rural Affairs 14th June 2018