This page intentionally left blank Drinking Water Quality This textbook provides a comprehensive review of the problems associated with the supply of drinking water in the developed world. Since the first edition of this book was published there have been enormous changes in the water industry, especially in the way drinking water is perceived and regulated. Water companies and regulators have been presented with numerous new challenges – global warming has seriously affected the sustainability of water supplies as well as impacting water quality; advances in chemical and microbial analysis have revealed many new contaminants in water that were previously undetectable or unknown; and recent terrorist attacks have demonstrated how vulnerable water supplies could be to contamination or disruption. This new edition is an overview of the current and emerging problems, and what can be done to solve them. It has been completely updated, and includes the new WHO Revised Drinking Water Guidelines. Drinking Water Quality is an ideal textbook for courses in environmental science, hydrology, environmental health, and environmental engineering. It also provides an authoritative reference for practitioners and professionals in the water supply industry. N. F. GRAY is a Professor at the Centre for the Environment at Trinity College, Dublin. He has worked in the area of water technology for 30 years, and is internationally known as a lecturer and author in water quality and pollution control. His research specializes in the operational problems associated with supplying drinking water and treating wastewaters. Drinking Water Quality Second Edition N. F. Gray University of Dublin CAMBRIDGE UNIVERSITY PRESS Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo Cambridge University Press The Edinburgh Building, Cambridge CB2 8RU, UK Published in the United States of America by Cambridge University Press, New York www.cambridge.org Information on this title: www.cambridge.org/9780521878258 © N. F. Gray 1994, 2008 This publication is in copyright. Subject to statutory exception and to the provision of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published in print format 2008 ISBN-13 978-0-511-39371-6 eBook (EBL) ISBN-13 978-0-521-87825-8 hardback ISBN-13 978-0-521-70253-9 paperback Cambridge University Press has no responsibility for the persistence or accuracy of urls for external or third-party internet websites referred to in this publication, and does not guarantee that any content on such websites is, or will remain, accurate or appropriate. Contents Preface page xiii Acknowledgements xvi Part I Introduction to water supply 1 The water business 3 1.1 Introduction 3 1.2 Water consumption 3 1.3 Acceptable water quality 7 1.4 Water utilities 10 1.5 Water conservation 18 1.6 Conclusions 33 References 35 2 Drinking water standards and risk 37 2.1 Introduction 37 2.2 Development of quality standards 37 2.3 Risk assessment in the development of health-based targets 39 2.4 Water safety plans 42 2.5 Drinking water standards 52 2.6 Conclusions 63 References 64 3 A quick guide to drinking water problems 65 3.1 Introduction 65 3.2 The problems 66 3.3 Conclusions 72 References 73 Part II Problems with the resource 4 Sources of water 77 4.1 Introduction 77 4.2 The water cycle 77 4.3 Surface waters: lakes, reservoirs and rivers 80 v vi Contents 4.4 Groundwater sources 89 4.5 Other sources of water 99 4.6 Conclusions 112 References 114 5 Nitrate and nitrite 116 5.1 Sources in water 116 5.2 Water quality standards 119 5.3 Effect on consumers 120 5.4 Nitrate in groundwaters 123 5.5 Nitrate in surface waters 125 5.6 Control of high-nitrate water 126 5.7 Conclusions 132 References 134 6 Pesticides and organic micro-pollutants 137 6.1 Organic micro-pollutants 137 6.2 Pesticides 139 6.3 Industrial solvents 156 6.4 Polycyclic aromatic hydrocarbons 160 6.5 Removal of organic contaminants from drinking water 162 6.6 Conclusions 163 References 165 7 Endocrine-disrupting compounds and PPCPs 169 7.1 Introduction and definitions 169 7.2 Pharmaceutical and personal care products (PPCPs) 171 7.3 Oestrogen and fertility 174 7.4 Conclusions 177 References 179 8 Odour and taste 181 8.1 Introduction 181 8.2 Standards and assessment 181 8.3 Classification 183 8.4 Odour-causing substances of natural origin 185 8.5 Man-made odour-causing substances 188 8.6 Conclusions 188 References 189 9 Metals 191 9.1 Iron 191 9.2 Manganese 193 9.3 Arsenic 194 9.4 Other metals 196 9.5 Removal by treatment 198 Contents vii 9.6 Conclusions 199 References 200 10 Hardness and total dissolved solids 203 10.1 Introduction 203 10.2 Chemistry of hardness 203 10.3 Standards 205 10.4 Health aspects 206 10.5 Conclusions 207 References 208 11 Algae and algal toxins 210 11.1 Introduction 210 11.2 Problems associated with algae 210 11.3 Standards 213 11.4 Treatment 213 11.5 Conclusions 214 References 215 12 Radon and radioactivity 217 12.1 Introduction 217 12.2 Radon 218 12.3 Non-radon radionuclides 219 12.4 Standards and treatment 220 12.5 Conclusions 222 References 223 13 Pathogens 225 13.1 Introduction 225 13.2 Protozoa 225 13.3 Viruses 229 13.4 Bacteria 231 13.5 Unusual sources of contamination 235 13.6 Conclusions 237 References 239 Part III Problems arising from water treatment 14 Water treatment 245 14.1 Introduction 245 14.2 Unit processes 246 14.3 Process selection 260 14.4 How problems arise 261 14.5 Conclusions 267 References 268 viii Contents 15 Aluminium and acrylamide 270 15.1 Aluminium 270 15.2 Acrylamide 277 15.3 Conclusions 278 References 279 16 Odour and taste 282 16.1 Source of odour and taste problems 282 16.2 Removing odours and tastes 283 16.3 Conclusions 285 References 285 17 Fluoridation 286 17.1 Introduction 286 17.2 Fluoride addition 287 17.3 Fluoridation and health 289 17.4 Fluoridation and public opinion 291 17.5 Who is at risk 292 17.6 Conclusions 293 References 295 18 Disinfection by-products 297 18.1 Formation 297 18.2 Standards 300 18.3 Health risks 301 18.4 Prevention of by-product formation 302 18.5 Conclusions 303 References 304 19 Monitoring and removal of pathogens 307 19.1 Introduction 307 19.2 Monitoring pathogens 307 19.3 Measurement and standards 308 19.4 Heterotrophic plate counts 313 19.5 Removal of pathogens 314 19.6 Disinfection 316 19.7 Conclusions 317 References 320 Part IV Problems arising in the distribution network 20 The distribution network 325 20.1 Introduction 325 20.2 Service reservoirs 325 20.3 Water mains 327 Contents ix 20.4 Service pipes 328 20.5 Conclusions 332 References 333 21 Aesthetic quality 334 21.1 Odour and taste 334 21.2 Discolouration and iron 335 21.3 Sediment and turbidity 338 21.4 Conclusions 340 References 340 22 Asbestos 342 22.1 The nature of asbestos 342 22.2 Health effects and standards 344 22.3 Asbestos cement distribution pipes 345 22.4 Conclusions 346 References 348 23 Coal-tar linings and polycyclic aromatic hydrocarbons 350 23.1 Introduction 350 23.2 Conclusions 351 References 352 24 Animals on tap 353 24.1 Microbial slimes in distribution pipes 353 24.2 Water supplies 355 24.3 Common species and remedial measures 356 24.4 Sampling water mains for animals 361 24.5 Microbial pathogens and invertebrates 362 24.6 Conclusions 363 References 364 25 Pathogens in the distribution system 366 25.1 Introduction 366 25.2 Microbial contamination 366 25.3 Control 369 25.4 Drinking water security 370 25.5 Conclusions 370 References 371 Part V Problems in household plumbing systems 26 Household plumbing systems 375 26.1 Entry to the home 375 26.2 Plumbing systems 375 x Contents 26.3 Water Byelaws and regulations 380 26.4 Conclusions 381 References 381 27 Corrosion and metal contamination from pipework and fittings 382 27.1 Introduction 382 27.2 Corrosion 382 27.3 Lead 387 27.4 Copper 400 27.5 Zinc 403 27.6 Conclusions 403 References 404 28 Micro-organisms, fibres and taste 407 28.1 Micro-organisms in plumbing systems 407 28.2 Fibres, including asbestos 410 28.3 Odour and taste 411 28.4 Conclusions 412 References 413 Part VI The water we drink 29 Alternatives to tap water 417 29.1 Introduction 417 29.2 Bottled water 417 29.3 Point-of-use water treatment 428 29.4 Water harvesting 436 29.5 Conclusions 438 References 441 30 Water security in the twenty-first century 442 30.1 Introduction 442 30.2 Vulnerability assessment 444 30.3 Developing security plans 444 30.4 The emergency response plan 447 30.5 Conclusions 450 References 451 31 Final analysis 453 31.1 Introduction 453 31.2 Complaints 454 31.3 Public perception of drinking water quality 455 31.4 The quality of drinking water 457 Contents xi 31.5 Water usage and conservation 460 31.6 Water conflict 461 31.7 Drinking water in developing countries 461 31.8 Conclusions 465 References 468 Appendix 1 EC Drinking Water Directive (98/83/EEC) quality parameters 469 Appendix 2 US National Primary and Secondary Drinking Water Standards of the US Environmental Protection Agency (2006) 471 Appendix 3 World Health Organization drinking water guide values for chemicals of health significance. Health-related guide values have not been set for a number of chemicals that are not considered hazardous at concentrations normally found in drinking water, although some of these compounds may lead to consumer complaints on aesthetic grounds.