Drinking water quality

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DRINKING WATER QUALITY

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Guidelines for drinking water quality By WHO Vol 1 in 1993 & vol 2 in 1996 Important variables Acceptability aspects Microbiological aspects Chemical aspects Radiological aspects

Acceptability aspects:

Acceptability aspects Physical parameters Turbidity- <4 NTU Colour- upto 15 TCU Taste & odour Temperature

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Inorganic Constituents Chlorides- std 200 mg/l max 600 mg/l Hardness- calcium- 100-300 mg/l Ammonia- NH3 & NH4+ upto 1.5mg/l pH - 6.5-8.5 <7 -corrosion >8- compromise efficiency of disinfection H2S - 0.05-0.1mg/l, rotten eggs odour Fe - 0.3 mg/l Na - 200mg/l

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Total dissolved salts TDS level <600 mg/l [good] < 1000mg/l [acceptable] >1200mg/l unpalatablee Sulphate <250mg/l CaSO4 – 270mg/l MgSO4 – 90mg/l Zn 4 mg/l ,astringent taste Mn 0.1 mg/l Dissolved O2 indirect effects,nitrate to nitrite, sulphate to sulphide Cu 1 mg/l Al 0.2 mg/l

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inorganic constituents Levels likely to give rise to consumer complaints Reasons for compliants Aluminium .2mg/ml Depitions,discolorations Ammonia 1.5mg/ml Odour,taste Chloride 250mg/ml Taste ,corrosions Copper 1mg/ml Staining of laundry &sanitary ware Hardness - High;scale deposition;scum formation;low-possible corrosion Hydrogen sulphide .05mg/ml Odour &taste Iron .3mg/ml Staining of laundry &sanitary ware Manganese .1mg/ml Staining of laundry &sanitary ware

MICROBIOLGICAL ASPECTS:

MICROBIOLGICAL ASPECTS Bacteriological indicators Virological aspects Biological aspects

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Bacteriological indicators Coliforms- faecal groups -E coli Non faecal –klebsiella aerogens Why coliforms???????? Coliforms are abundant in intestine(200-400billion/day) Easily detected by culture Survive longer than pathogens Greater resistance to forces of natural purification Faecal streptococci - recent faecal pollution resist drying Clostridium perfringes - remote infection resist chlorination

Virological aspects:

Virological aspects Free from virus Disinfect with 0.5 mg/ml of free cl residual after contact period of at least 30 minutes at pH 8 in hep A endemic areas. others need 0.2 mg/ml Ozone 0.2-0.4 mg/ml for 4 minutes

Biological aspects:

Biological aspects Protozoa-E.histolytica ,Balantidium coli(animal/ human fecal contamination) Helminths- infective form of round worm, hook worm dracunculus medinensis,schistosomes Free living;fungi ,algae interfere with water treatment

Chemical aspects:

Chemical aspects Inorganic constituents Organic constituents

INORGANIC CONSTITUENTS:

INORGANIC CONSTITUENTS Inorganic constituents Guideline value Arsenic 0.01mg/l Cadmium 0.003ug/l Chromium 0.05 mg/l Cyanide 0.07 mg/l Fluoride 1.5mg/l Lead 0.01mg/l Mercury 0.01 mg/l Nitrate 50mg/l Nitrate 3mg/l Selenium 0.01mg/l

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Cadmium- accumulate in kidney, long T1/2- 10-35y Flouride- >5 mg/l dental & skeletal flurosis Lead – placental transfer -12 th week and continues, interfere with Ca2+ metabolism, renal tumors subencephalopathic neurological &behavioural effects Nitrate & nitrite – nitrate - 50 mg/l nitrite – 3 mg/l conc: of nitrate + conc:of nitrite = < 1 G.value of nitrate G.value of nitrite

ORGANIC CONSTITUENTS:

ORGANIC CONSTITUENTS ORGANIC CONSTITUENTS UPPER LIMIT OF CONC(mcg/l) CHLORINATED ALKANES CCl4 2 dichloromethane 20 CHLORINATED ETHENES Vinyl chloride 55 1.1-dichloroethene 30 1.2-dichloroethene 50 AROMATIC HYDROCARBONS benzene 10 toluene 700 xylene 500 Ethyl benzene 300 styrene 20

Drinking water consumption & bodyweight:

Drinking water consumption & bodyweight Adult- 2L/d Child of 10 kg-1L/d Infant of 5kg-.75L/d Health risk assessment Tolerable daily intake(TDI) Amount of a substance in food or drinking water expressed on a body weight basis that can be ingested daily over a lifetime without appreciable health risk Acceptable daily intake(ADI) For food additives & pesticides

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No-Observed-Adverse –Effect-Level(NOAEL) Highest dose or concentration of a chemical in a single study,found by experiment or observation that causes no detectable adverse health effects Lowest-Observed-Advers-Effect-Level(LOAEL) Lowest observed dose or concentration of a substance at which there is a detectable adverse health effects Uncertainity factor (UF) sources inter species variation,intra species variation adequacy of studies, nature &severity of effect

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UF do not exceed 10000 TDI = NOAEL/LOAEL UF GV = TDI *bw*P C Bw- body weight P-fraction of the TDI allocated to drinking water C-daily drinking water cosumption

Radiological aspects:

Radiological aspects Somatic ; exposed individuals Hereditary ;affect descendants DW- safe limits + reasonably low Becquerel - 1 disintegration/sec GV- gross alpha activity 0.1 Bq/L gross beta activity 1 Bq/L

Surveillance of drinking water quality:

Surveillance of drinking water quality

Activities in surveillance function:

Activities in surveillance function Approval of new sources Watershed protection Approval-construction & operating procedures of warer works disinfection of the plant & distribution system periodic flushing programmes & cleaning of water storage facilities certification of operators regulation of chemical substances Cross-connection control ,back flow prevention,leak detection control Sanitary surveys Monitoring programmes

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Development of codes of practice for well construction ,pump installation and plumbing Inspection quality control in bottled water

Elements of surveillance programme :

Elements of surveillance programme S ANITARY SURVEY SAMPLING BACTERIOLOGICAL SURVEILLANCE 1)Presumptive Coliform test - MULTIPLE TUBE METHOD MEMBRANE FILTRN TECHNIQUE 2)Detection of faecal strep & cl.perfringes 3)Colony count BIOLOGICAL EXAMINATION CHEMICAL SURVEILLANCE

Membrane filteration technique:

Membrane filteration technique

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Thank u 

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