Guidelines for Drinking-water Quality

1 Guidelines for Drinking-water QualityFOURTH EDITION WHO Library Cataloguing-in-Publication DataGuidelines for Drinking-water Quality - 4th ed. water - standards. - standards. Quality - standards. Health 978 92 4 154815 1 (NLM classification: WA 675) World Health Organization 2011 All rights reserved. Publications of the World Health Organization are available on the WHO web site ( ) or can be purchased from WHO Press, World Health Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland (tel.: +41 22 791 3264; fax: +41 22 791 4857; e-mail: Requests for permission to reproduce or translate WHO publications whether for sale or for non- commercial distribution should be addressed to WHO Press through the WHO web site ( ).)

2 The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full mention of specific companies or of certain manufacturers products does not imply that they are endorsed or recommended by the World Health Organization in preference to others of a similar nature that are not mentioned. Errors and omissions excepted, the names of proprietary products are distinguished by initial capital reasonable precautions have been taken by the World Health Organization to verify the information contained in this publication.

3 However, the published material is being distributed without warranty of any kind, either expressed or implied. The responsibility for the interpretation and use of the material lies with the reader. In no event shall the World Health Organization be liable for damages arising from its use. Cover designed by WHO Graphics, SwitzerlandTypeset by Value Chain, IndiaPrinted in Malta by GutenbergiiiContentsPreface xvAcknowledgements xviiAcronyms and abbreviations used in text xx1. Introduction General considerations and principles Framework for safe Drinking-water Microbial aspects Disinfection Chemical aspects Radiological aspects Acceptability aspects: taste, odour and appearance Roles and responsibilities in Drinking-water safety management Surveillance and Quality control Public health authorities Local authorities water resource management Drinking-water supply agencies Community management water vendors Individual consumers Certification agencies Plumbing Supporting resources to the Guidelines Published documents Capacity-building networks 182.

4 A conceptual framework for implementing the Guidelines Health-based targets water safety plans System assessment and design Operational monitoring Management plans, documentation and communication 24ivGUIDELINES FOR Drinking-water Surveillance Verification of Drinking-water Quality Microbial water Quality Chemical water Quality Identifying priority concerns Undertaking a Drinking-water Quality assessment Assessing microbial priorities Assessing chemical priorities Developing Drinking-water Quality standards Adapting guideline values to locally relevant standards Periodic review and revision of standards Drinking-water regulations and supporting policies and programmes Regulations Supporting policies and programmes 333.

5 Health-based targets Setting health-based targets Disability-adjusted life years, tolerable disease burden and reference level of risk Types of health-based targets Health outcome targets water Quality targets Performance targets Specified technology targets 434. water safety plans System assessment and design New systems Collecting and evaluating available data Resource and source protection Treatment Piped distribution systems Non-piped, community and household systems Validation 59 Upgrade and improvement Operational monitoring and maintaining control Determining system control measures Selecting operational monitoring parameters Establishing operational and critical limits Non-piped, community and household systems Verification Verification of microbial Quality Verification of chemical Quality Source waters Piped distribution systems Verification for community-managed supplies Quality assurance and Quality control Verification of water safety plans Management procedures for piped distribution systems Predictable incidents ( deviations ) Unplanned events Emergencies Preparing a monitoring plan Supporting programmes Management of community and household water supplies Documentation and communication Planned review Periodic review Post-incident review 765.

6 Surveillance Types of approaches Audit Direct assessment Adapting approaches to specific circumstances Urban areas in developing countries Surveillance of community Drinking-water supplies Surveillance of household treatment and storage systems Adequacy of supply Quantity (service level) Accessibility Affordability Continuity Planning and implementation Reporting and communicating Interaction with community and consumers Regional use of data 906. Application of the Guidelines in specific circumstances Climate change, water scarcity and heavy rainfall Rainwater harvesting Vended water Bulk water supply Desalination systems Dual piped water supply systems Emergencies and disasters Temporary water supplies Buildings Health-care facilities Safe Drinking-water for travellers Aircraft and airports Ships 112viGUIDELINES FOR Drinking-water Packaged Drinking-water Food production and processing 1167.

7 Microbial aspects Microbial hazards associated with Drinking-water Waterborne infections Emerging issues Persistence and growth in water Public health aspects Health-based target setting Health-based targets applied to microbial hazards Reference pathogens Quantitative microbial risk assessment Risk-based performance target setting Presenting the outcome of performance target development Adapting risk-based performance target setting to local circumstances Health outcome targets Occurrence and treatment of pathogens Occurrence Treatment Microbial monitoring Methods of detection of faecal indicator organisms Identifying local actions in response to microbial water Quality problems and emergencies Boil water advisories Actions following an incident 1538.

8 Chemical aspects Chemical hazards in Drinking-water Derivation of chemical guideline values Approaches taken Threshold chemicals Non-threshold chemicals Data Quality Provisional guideline values Chemicals with effects on acceptability Chemicals not included in the Guidelines Mixtures Adapting guideline values to local circumstances Analytical achievability Treatment Treatment performance Process control measures for disinfection by-products Treatment for corrosion control Household treatment Guideline values for individual chemicals, by source category Naturally occurring chemicals Chemicals from industrial sources and human dwellings Chemicals from agricultural activities Chemicals used in water treatment or from materials in contact with Drinking-water Chemicals of emerging concern Pesticides used in water for public health purposes Identifying local actions in response to chemical water Quality problems and emergencies Trigger for action Investigating the situation Talking to the right people Informing the public Evaluating the significance to public health and individuals 195 Determining appropriate action Consumer acceptability Ensuring remedial action.

9 Preventing recurrence and updating the water safety plan Mixtures water avoidance advisories 2009. Radiological aspects Sources and health effects of radiation exposure Radiation exposure through ingestion of Drinking-water Radiation-induced health effects through Drinking-water Rationale for screening levels and guidance levels Monitoring and assessment for dissolved radionuclides Screening of Drinking-water supplies Strategy for assessing Drinking-water if screening levels are exceeded Strategy for assessing Drinking-water if guidance levels are exceeded Sampling frequency Guidance levels for radionuclides commonly found in Drinking-water Analytical methods Measuring gross alpha and gross beta activity concentrations Measuring specific radionuclides Remedial measures Radon Radon in air and

10 water Health risks from radon Guidance on radon in Drinking-water supplies Measuring radon in Drinking-water 217viiiGUIDELINES FOR Drinking-water Decreasing radon concentrations in Drinking-water Risk communication Reporting results Communicating risks 21710. Acceptability aspects: Taste, odour and appearance Biologically derived contaminants 221 Actinomycetes and fungi 221 Cyanobacteria and algae 221 Invertebrate animal life 221 Iron bacteria Chemically derived contaminants 222 Aluminium 222 Ammonia 223 Chloramines 223 Chloride 223 Chlorine 223 Chlorobenzenes 223 Chlorophenols 224 Colour 224 Copper 224 Dissolved oxygen 225 Ethylbenzene 225 Hardness 225 Hydrogen sulfide 225 Iron 226 Manganese 226 Petroleum oils 226 pH and corrosion 226 Sodium 227 Styrene 227 Sulfate 227 Synthetic detergents 227 Toluene 228 Total dissolved solids 228 Turbidity 228 Xylenes 229 Zinc Treatment of taste, odour and appearance problems Temperature 23011.