International Standard Specifications For Drinking Water LECTURE 8 PDF

International standard specifications for drinking water LECTURE 8 SAFE AND WHOLESOME WATER Free from pathogenic agents. Free from harmful chemical substances. Pleasant to the taste i.e. free from colour and odour Usable for domestic purposes. ...

International standard specifications for drinking water LECTURE 8 SAFE AND WHOLESOME WATER Free from pathogenic agents. Free from harmful chemical substances. Pleasant to the taste i.e. free from colour and odour Usable for domestic purposes.  FRAMEWORK FOR SAFE DRINKING-WATER: REQUIREMENTS Health-based targets System assessment Operational monitoring Management plan and monitoring plans - describing actions to be taken in normal operation and incident conditions A system of independent surveillance HEALTH BASED TARGETS Mark out milestones to guide and chart progress towards a predetermined health and/or water safety goal. Provides opportunity to take action to correct deficiencies. Identifies data needs and discrepancies. TYPES OF HEALTH-BASED TARGETS Health outcome targets : Measures reduction in detected disease incidence or prevalence. Microbial or chemical hazards with high measurable disease burden largely water associated. For eg. Flouride. WATER QUALITY TARGETS (WQTS): Established for individual drinking-water constituents that represent a health risk from long-term exposure and where fluctuations in concentration are small or occur over long periods. Expressed as guideline values (concentrations) of the substances or chemicals of concern.  PERFORMANCE TARGETS: Employed for constituents where short-term exposure represents a public health risk or where large fluctuations in numbers or concentration can occur over short periods with significant health implications. Most frequently applied to the control of microbial hazards in piped supplies varying from small to large. SPECIFIED TECHNOLOGY TARGETS: National regulatory agencies establish targets for specific actions for smaller municipal, community and household drinking-water supplies. Identify specific permissible devices or processes for given situations and/or for generic drinking-water system types. WATER SAFETY PLANS A WSP comprises of the three essential actions that are the responsibility of the drinking-water supplier in order to ensure that drinking-water is safe. a system assessment. effective operational monitoring; and management. guided by health-based targets and overseen through drinking-water supply surveillance. Water safety plans The primary objectives of a WSP in ensuring good drinking-water supply practice are : Minimization of contamination of source waters. Reduction or removal of contamination through treatment processes. Prevention of contamination during storage, distribution and handling of drinking-water. SYSTEM ASSESSMENT AND DESIGN Multidisciplinary team of experts with a thorough understanding of the drinking water system. For eg. engineers, catchment & water managers, water quality specialists, environmental or public health or hygienist professionals, operational staff and representatives of consumers.  Provides an overview description of the drinking- water system, including characterization of the source, identification of potential pollution sources in the catchment, measures for resource and source protection, treatment processes, storage and distribution infrastructure. OPERATIONAL MONITORING The objectives of operational monitoring are for the drinking-water supplier to monitor each control measure in a timely manner to enable effective system management and to ensure that health-based targets are achieved. PARAMETERS USED IN OPERATIONAL MONITORING For source waters- Turbidity UV absorbency Algal growth Flow and retention time Colour, conductivity and local meteorological events  For treatment- Disinfectant concentration and contact time UV intensity pH Light absorbency Membrane integrity Turbidity and Colour  In piped distribution systems-- Chlorine residual monitoring -- A sudden disappearance of an otherwise stable residual can indicate ingress of contamination. Faecal indicator bacteria Pressure measurement and turbidity are also useful in operational monitoring. MANAGEMENT PROCEDURES Effective management implies definition of actions to be taken in response to variations that occur during normal operational conditions; of actions to be taken in specific incident situations where a loss of control of the system may occur; and of procedures to be followed in unforeseen and emergency situations. Management procedures should be documented alongside system assessment, monitoring plans, supporting program and communication required to ensure safe operation of the system. WATER QUALITY CONTROL To ensure that water services meet agreed national standards & institutional targets. Provides valuable information: Quality of source of water. Efficiency of treatment and water quality variables. Natural and seasonal variations. Identifies need for taking remedial action. WATER QUALITY SURVEILLANCE “The continuous and vigilant public health assessment and review of the safety and acceptability of drinking-water supplies” (WHO, 1976). Done by independent agency (state public health department). Investigates the activity and identifies the corrective or preventive measures and gives feedback to water supplying agency.  This surveillance contributes to the protection of public health by promoting improvement of the quality, quantity, accessibility, coverage, affordability and continuity of water supplies (known as service indicators). Complementary to the quality control function. EFFECTIVE SURVEILLANCE INCLUDES: Regular testing of residual chlorine at consumer level. Regular collection of water samples and testing of water samples for E. coli or thermotolerant bacteria and coliform count. Regular interaction with supplying agency. Monitor water borne diseases for early warning.  Monitor outbreaks of water borne diseases. Sanitary inspection. Education of safe water to people. Training of community members for home and well chlorination. Intersectoral coordination. SANITARY INSPECTION On-site inspection and evaluation by qualified individuals of all conditions, devices, and practices in the water supply system that pose an actual danger to the health and well being of the consumers. WATER SAMPLING AND ANALYSIS Minimum level of analysis should include: Testing for indicators for faecal pollution. Turbidity Chlorine (residual) pH LOCATION OF SAMPLING POINTS Representative of the different sources from which water is obtained by the public or enters the system. Representative of the conditions at the most unfavourable sources SAMPLING FREQUENCY IN PIPED WATER SYSTEM POPULATION No. OF MONTHLY SERVED SAMPLES 100,000- 1/10,000 population 500,000 +10 additional samples >500,000 1/10,000 population +50 additional samples SAMPLING METHODS FOR PHYSICOCHEMICAL ANALYSIS Collected in clean glass stoppered bottles– WINCHESTER QUART BOTTLES. Rinse three times with water before filling. Stored at low temperature(40C)  SAMPLES FOR BACTERIOLOGICAL EXAMINATION Clean sterilized bottle, 200-250 ml. Add sodium thiosulphate, if sample contains chlorine. Should not be opened before filling. Collect sample. Examine or keep in ice until analyzed. Iced sample should be analysed within 48 hrs after collection. WATER QUALITY – CRITERIA AND STANDARDS I. Acceptability aspects II. Microbiological aspects III. Chemical aspects IV. Radiological aspects  ACCEPTABILTY ASPECTS PHYSICAL PARAMETERS AND INORGANIC CONSTITUENTS  Inorganic Permissible Reasons Treatment constituent level Turbidity 5 NTU* Appearance Filtration Colour 15 TCU** Appearance Filtration, Distillation, Reverse osmosis, Ozonisation * NTU :stands for Nephelometric Turbidity unit, i.e. the unit used to measure the turbidity of a fluid or the presence of suspended particles in water ** TCU: True Colour Units  Inorganic Permissible Reasons Treatment constituent level Taste and ------ Should be Activated carbon, air stripping, odour acceptable oxidation, filtration Temperature ------- Should be ------- acceptable Inorganic Permissible Reasons Treatment constituent level Aluminium 0.2mg/l Deposition, Neurological discoloration disorders, Alzheimer’ disease Ammonia 1.5 mg/l Odour & taste Algal growth Inorganic Permissible Reasons Treatment constituent level Chloride 250mg/l Taste & ----------- corrosion Hardness ---------- Scale deposition, Removed by scum formation, ion exchange, corrosion RO* *RO: Reverse osmosis Inorganic Permissible Reasons Treatment constituent level Hydrogen 0.05 mg/l Odour Activated sulfide and taste carbon, air stripping, oxidation, filtration Iron 0.3 mg/l Staining Oxidizing filter Inorganic Permissible Reasons Treatment constituent level Manganese 0.1 staining Ion exchange, mg/l chlorination, oxidizing filter, Dissolved -------- Indirect ----------- oxygen effects Inorganic Permissible Reasons Treatment constituent level pH 6.5 – 8.5 Low – Increase corrosion pH- by High-taste, soda ash soapy feel Decrease pH – by citric acid Sodium 200 mg/l Taste ------- Inorganic Permissible Reasons Treatment constituent level Sulphate 250 mg/l Taste, RO, corrosion distillation, ion exchange Total 1000 mg/l Taste RO, dissolved distillation, solids ion exchange Zinc 3 mg/l Taste same MICROBIOLOGICAL ASPECTS Total Coliform Bacteria Permissible Nil in 100ml sample level Risks or effects Gastrointestinal illness Livestock facilities, septic systems, manure lagoons Sources Household waste water Naturally occurring Treatment Chlorination , Ultraviolet, Distillation, Iodination E.coliform Bacteria Permissible Nil / 100ml level Risks or effects Gastrointestinal illness Livestock facilities, septic systems, manure lagoons Sources Household waste water Naturally occurring Treatment Chlorination , Ultraviolet, Distillation, Iodination Total Coliform Bacteria and E.coliform Bacteria E.Coliform or Thermotolerant Bacteria Nil / 100ml(Drinking Water, Water entering distribution System, Distribution System) Total coliform bacteria Permissible level Nil / 100ml(Drinking Water, Water entering distribution System, Distribution SystemIn case of large supplies, where sufficient samples are examined, must not be present in 95% of any samples taken throughout 12mths period.) Risks or effects Gastrointestinal illness Livestock facilities, septic systems, manure lagoons Sources Household waste water Naturally occurring Treatment Chlorination , Ultraviolet, Distillation, Iodination Tests employed are: 1. Presumptive coliform test: Multiple tube method Membrane Filtration Technique 2. Tests for detection of faecal streptococci and Cl. Perfringes. 3. Colony count Virological examination Drinking water should be free from viral infection. MS2 phage is indicator of viral contamination in water, If detected ; virological examination shall be done by the PCR method. > 0.5 mg/l of free chlorine for one hour is sufficient to inactivate virus, even in water that was originally polluted. A redox potential of 650 mV cause almost inactivation of high concentration of virus. Ozone also has strong virucidal effect. Biological Examination – Water should be free from algae, zooplanktons, flagellates, parasites and toxin producing organisms. Examination: Chlorination Filtration Flocculation Microscopic examination CHEMICAL ASPECTS INORGANIC CHEMICALS: Constituents Recommended max limit (mg/l) Antimony 0.005 Arsenic 0.01 Barium 0.7 Boron 0.3 Cadmium (batteries, 0.003 fertilizers) Chromium 0.05 Copper 2 Cyanide(industrial 0.07 contamination) Fluoride (geographical 1.5 area) Lead (household 0.01 plumbing system) Manganese 0.5 Mercury 0.001 Molybdenum 0.07 Nickel 0.02 Nitrate 50 Nitrite 3 Selenium 0.01  ORGANIC CONSTITUENTS Constituents Max limit (μg/L) Carbon tetrachloride 2 Dichloromethane 20 Vinyl chloride 55 1.1-dichloroethane 30 1.2-dichloroethane 50  AROMATIC HYDROCARBON Benzene 10 Toluene 700 Xylenes 500 Ethyl benzene 300 Styrene 20 Benzolalpyrene 0.7 PESTICIDES MAX LIMIT(μg/L) Aldrin 0.03 Chlordane 0.2 DDT 2 2,4-D 30 Heptachlor 0.03 Hexachlorbenzene 1 Lindane 2 Methoxychlor 20 Pentachlorophenol 9 RADIOLOGICAL ASPECTS Should be as low as possible Proposed guideline value: Gross alpha activity – 0.1Bq/L Gross beta activity – 1.0Bq/L