BOOK
Assessing Microbial Safety of Drinking Water
A. Dufour | M. Snozzi | W. Koster | Jamie Bartram | E. Ronchi | Lorna Fewtrell
(2003)
Additional Information
Book Details
Abstract
Inadequate drinking water quality and poor sanitation have remained the world's major causes of preventable morbidity and mortality. In 1996 the OECD called for concerted action to improve the assessment and management of the world's sources of drinking water. This guidance document seeks to respond to this call. It is the product of a shared initiative between the OECD and the World Health Organization. It is a state-of-the-art review that will contribute to the revisions of the WHO's Guidelines for Drinking Water Quality. Assessing Microbial Safety Of Drinking-water has elements of both revolution and evolution. It is revolutionary in that it supports a rapidly emerging approach for a broader, system-wide management perspective. This is based on a risk management framework that has evolved from the traditional indicator concept to include multiple parameters and where consideration is also given to tolerable risk, water quality targets and public health status.
Table of Contents
| Section Title | Page | Action | Price |
|---|---|---|---|
| Cover\r | Cover | ||
| TABLE OF CONTENTS | 9 | ||
| Chapter 1:\rSAFE DRINKING WATER: AN ONGOING CHALLENGE | 11 | ||
| 1.1 Introduction\r | 11 | ||
| 1.1.1 Outbreaks of waterborne disease | 11 | ||
| 1.1.2 The disease burden is high | 12 | ||
| 1.1.3 New pathogens emerge | 14 | ||
| 1.2 A history of making water safer | 14 | ||
| 1.2.1 Refinement | 16 | ||
| 1.3 Defining the role of the indicator concept | 18 | ||
| 1.3.1 Current practice | 20 | ||
| 1.3.2 New challenges | 21 | ||
| 1.4 Emergence of a new paradigm: “Due diligence” | 23 | ||
| 1.5 Direct pathogen testing | 26 | ||
| 1.5.1 Dose-response relationships for pathogens | 28 | ||
| 1.5.2 Molecular technologies | 29 | ||
| 1.6 Information needs | 31 | ||
| 1.6.1 Regulation | 31 | ||
| 1.6.2 Water supplier | 32 | ||
| 1.6.3 Public health agencies | 33 | ||
| 1.7 The new approach: Total System Approach to Risk Management | 34 | ||
| 1.8 Summary | 36 | ||
| REFERENCES | 37 | ||
| Chapter 2:\rINTRODUCING PARAMETERS FOR THE ASSESSMENT OF DRINKING WATER QUALITY | 47 | ||
| 2.1 Introduction | 47 | ||
| 2.2 Microbial parameters | 48 | ||
| 2.2.1 The coliform group | 49 | ||
| 2.2.2 Enterococci and faecal streptococci | 53 | ||
| 2.2.3 Ratios of counts | 54 | ||
| 2.2.4 Direct total counts and activity tests (total and viable bacteria) | 54 | ||
| 2.2.5 Heterotrophic aerobic and aerobic spore-former bacterial counts | 55 | ||
| 2.2.6 Bacteriophages | 56 | ||
| 2.2.7 Sulphite-reducing clostridia and Clostridium perfringens | 58 | ||
| 2.2.8 Pseudomonas aeruginosa and Aeromonas spp. | 58 | ||
| 2.2.9 Presence-absence test | 59 | ||
| 2.2.10 Hydrogen sulphide test | 60 | ||
| 2.2.11 Other microorganisms | 61 | ||
| 2.2.12 Pathogens | 61 | ||
| 2.3 Non-microbial parameters | 64 | ||
| 2.3.1 Rainfall events | 65 | ||
| 2.3.2 Flow | 65 | ||
| 2.3.3 Colour | 66 | ||
| 2.3.4 pH | 66 | ||
| 2.3.5 Solids | 66 | ||
| 2.3.6 Turbidity | 67 | ||
| 2.3.7 Particle size analysis | 69 | ||
| 2.3.8 Microscopic particulate analysis | 69 | ||
| 2.3.9 Disinfectant residual concentration | 70 | ||
| 2.3.10 Organic matter | 70 | ||
| 2.3.11 Specific chemical parameters | 70 | ||
| 2.4 Summary | 72 | ||
| REFERENCES AND FURTHER READING | 74 | ||
| Chapter 3:\rASSESSMENT OF RISK | 79 | ||
| 3.1 Introduction | 79 | ||
| 3.2 What is risk? | 80 | ||
| 3.3 Types of evidence | 80 | ||
| 3.4 Epidemiological approaches to risk | 82 | ||
| 3.5 Studies linking ill health to indicators | 83 | ||
| 3.5.1 Untreated drinking waters | 84 | ||
| 3.5.2 Substandard drinking water | 85 | ||
| 3.5.3 Drinking water meeting current regulations | 85 | ||
| 3.5.4 The role of index/indictor parameters in assessing risk to health | 86 | ||
| 3.6 Quantitative microbial risk assessment (qmra) | 87 | ||
| 3.6.1 The mathematical modelling of health risk | 87 | ||
| 3.6.2 Hazard identification (hazard assessment) | 88 | ||
| 3.6.2.1 Outbreaks | 88 | ||
| 3.6.2.2 ‘Emerging’ pathogens | 89 | ||
| 3.6.3 Dose-response analysis | 90 | ||
| 3.6.4 Exposure assessment | 92 | ||
| 3.6.5 Infectious disease models and risk characterisation | 94 | ||
| 3.7 Qualitative risk assessment | 96 | ||
| 3.7.1 Indicators and qualitative microbial risk assessment | 99 | ||
| 3.8 Summary | 100 | ||
| REFERENCES | 101 | ||
| Chapter 4:\rCATCHMENT CHARACTERISATION AND SOURCE WATER QUALITY | 111 | ||
| 4.1 Introduction\r | 111 | ||
| 4.1.1 Select the best available source | 111 | ||
| 4.1.2 Catchment protection | 112 | ||
| 4.2 Sources of faecal contamination | 113 | ||
| 4.2.1 Sources of surface water pollution | 114 | ||
| 4.2.2 Sources of groundwater pollution | 116 | ||
| 4.3 Transport and survival | 118 | ||
| 4.3.1 Survival in surface water | 119 | ||
| 4.3.2 Transport in surface water | 120 | ||
| 4.3.3 Survival in groundwater | 122 | ||
| 4.3.4 Groundwater transport | 123 | ||
| 4.4 Catchment surveys and catchment protection | 125 | ||
| 4.4.1 Surface water | 126 | ||
| 4.4.1.1 Catchment survey | 126 | ||
| 4.4.1.2 The use of microbial parameters as an index of faecal pollution | 127 | ||
| 4.4.1.3 The use of pathogenic microorganisms | 128 | ||
| 4.4.2 Groundwater | 129 | ||
| 4.4.2.1 Catchment survey | 129 | ||
| 4.4.2.2 The use of microbial indicators as an index of faecal pollution | 135 | ||
| 4.5 Source water quality | 137 | ||
| 4.5.1 Surface water | 138 | ||
| 4.5.1.1 The use of microbial parameters to set treatment goals | 138 | ||
| 4.5.1.2 The use of pathogens to set treatment goals | 139 | ||
| 4.5.1.3 Peak events | 140 | ||
| 4.5.2 Groundwater | 143 | ||
| 4.5.2.1 Turbidity and temperature profile | 145 | ||
| 4.5.2.2 Pathogens as self-indicators | 145 | ||
| 4.6 Summary and outlook | 146 | ||
| REFERENCES | 148 | ||
| Chapter 5:\rTREATMENT EFFICIENCY | 159 | ||
| 5.1 Introduction | 159 | ||
| 5.2 Microbial treatment efficiency | 161 | ||
| 5.2.1 Coagulation and sedimentation | 161 | ||
| 5.2.2 Filtration | 162 | ||
| 5.2.2.1 Rapid filtration | 163 | ||
| 5.2.2.2 Slow sand filtration | 164 | ||
| 5.2.2.3 Activated carbon filtration | 165 | ||
| 5.2.2.4 Membrane filtration | 165 | ||
| 5.2.3 Chemical inactivation | 166 | ||
| 5.2.3.1 Chlorination | 167 | ||
| 5.2.3.2 Ozonation | 169 | ||
| 5.2.3.3 UV disinfection | 170 | ||
| 5.2.3.4 Solar water disinfection | 173 | ||
| 5.3 Summary | 175 | ||
| REFERENCES | 176 | ||
| Chapter 6:\rMONITORING THE QUALITY OF DRINKING WATER DURING STORAGE AND DISTRIBUTION | 179 | ||
| 6.1 Introduction | 179 | ||
| 6.2 Piped distribution systems | 180 | ||
| 6.2.1 Inadequately treated water entering the distribution system | 180 | ||
| 6.2.2 Integrity of the distribution system | 181 | ||
| 6.2.3 Microbial re-growth in the distribution system | 183 | ||
| 6.3 Non-piped distribution systems | 183 | ||
| 6.4 Approaches to sampling in piped distribution systems | 185 | ||
| 6.4.1 Choice of indicator parameter | 186 | ||
| 6.4.2 Location of sampling points | 188 | ||
| 6.4.3 Frequency of sampling | 189 | ||
| 6.4.4 Volume of sample | 190 | ||
| 6.4.5 Sample collection | 191 | ||
| 6.5 Approaches to sampling in non-piped systems | 193 | ||
| 6.5.1 Selection of methods and indicator organisms | 194 | ||
| 6.5.2 Water quality sampling approaches | 194 | ||
| 6.5.2.1 Year-groups approach | 195 | ||
| 6.5.2.2 Longitudinal study sample | 195 | ||
| 6.5.2.3 Assessment only approaches | 196 | ||
| 6.5.4 Tanker trucks and vendors | 196 | ||
| 6.5.5 Household water | 197 | ||
| 6.6 Summary | 198 | ||
| REFERENCES | 199 | ||
| Chapter 7:\rSURVEILLANCE AND INVESTIGATION OF CONTAMINATION INCIDENTS AND WATERBORNE OUTBREAKS | 205 | ||
| 7.1 Introduction | 205 | ||
| 7.2 Waterborne outbreaks | 207 | ||
| 7.3 Preventing outbreaks | 209 | ||
| 7.3.1 Incident management | 210 | ||
| 7.3.2 Response to specified incidents | 211 | ||
| 7.3.3 Response to unspecified incidents | 212 | ||
| 7.3.4 Water avoidance and boil water orders | 213 | ||
| 7.4 Outbreak investigation | 214 | ||
| 7.5 Reviewing existing data | 217 | ||
| 7.6 Enhanced monitoring including pathogen detection | 218 | ||
| 7.6.1 Pathogen detection | 220 | ||
| 7.6.2 Molecular techniques | 222 | ||
| 7.6.3 Negative results | 223 | ||
| 7.6.4 Pathogen typing and strain characterisation | 223 | ||
| 7.7 Summary | 228 | ||
| REFERENCES | 230 | ||
| Chapter 8:\rANALYTICAL METHODS FOR MICROBIOLOGICALWATER QUALITY TESTING | 237 | ||
| 8.1 Introduction | 237 | ||
| 8.2 Recovery of target microorganisms | 238 | ||
| 8.2.1 Filtration methods | 238 | ||
| 8.2.1.1 Virus adsorption-elution methods | 239 | ||
| 8.2.1.2 Ultrafiltration | 240 | ||
| 8.2.2 Immunocapture | 241 | ||
| 8.2.3 Flocculation | 242 | ||
| 8.2.4 Centrifugation | 243 | ||
| 8.2.4.1 Continuous flow centrifuge | 243 | ||
| 8.2.4.2 Gradient density separation/isolation | 244 | ||
| 8.2.5 Flow cytometry | 245 | ||
| 8.2.6 Pre-enrichment and enrichment techniques | 246 | ||
| 8.2.7 Other techniques | 247 | ||
| 8.2.7.1 Hydro-extraction | 247 | ||
| 8.2.7.2 Solvent-extraction | 248 | ||
| 8.3 Detection, identification and quantification of microorganisms | 248 | ||
| 8.3.1 Cultivation techniques | 248 | ||
| 8.3.1.1 Cultivation of bacteria | 248 | ||
| 8.3.1.2 Cultivation in host cells | 254 | ||
| 8.3.1.3 Standardisation of methods | 256 | ||
| 8.3.2 Detection and identification | 263 | ||
| 8.3.2.1 Polymerase chain reaction (PCR) – based detection | 265 | ||
| 8.3.2.2 Fluorescence in situ hybridisation (FISH) | 268 | ||
| 8.4 Emerging procedures | 271 | ||
| 8.4.1 Laser scanning analysis | 271 | ||
| 8.4.2 DNA – chip array | 272 | ||
| 8.4.3 Biosensors | 273 | ||
| 8.4.4 Solid state biochips | 273 | ||
| 8.5 Performance and validation of methods | 274 | ||
| 8.5.1 Limitations and characteristics of microbiological methods | 274 | ||
| 8.5.2 Statistical issues | 275 | ||
| 8.5.3 Validation of methods | 275 | ||
| 8.6 Summary | 277 | ||
| REFERENCES | 283 | ||
| LIST OF ABBREVIATIONS | 293 |