DR. RUKHSANA KHALID

2. DR. RUKHSANA KHALID

3. DO YOU KNOW????

7. Water quality refers to the physical, chemical, biological and radiological characteristics of water. It is the measure of the condition of water relative to the requirements of one or more biotic species and or to any human need or purpose.

8. WATER QUALITY INDICES Water quality indices for drinking water may be classified as follows: Guidelines recommended by WHO in 2011 for water quality relate to: 1. Acceptability aspects. 2. Microbiological aspects. 3. Chemical aspects. 4. Radiological aspects.

9. 1. ACCEPTABILITY ASPECTS: Safe drinking water should be: - Free from colour - Free from turbidity - Free from odour - Free from disagreeable taste

10. 2. MICROBIOLOGICAL ASPECTS Ideally drinking water should not contain any micro-organisms known to be pathogenic. The primary bacterial indicator is the coliform group of organisms.

11. a. Coliform organisms: Include - all aerobes - facultative anaerobes - gram negative, non spore forming, motile & non motile rods capable of fermenting lactose.

12. b. Faecal streptococci: - It is present in faeces but in smaller amounts. - The finding of faecal streptococci in water is regarded as important confirmatory evidence of recent faecal pollution of water.

13. c. Cl. perfringens: - They are also present in faeces. - Their spores are capable of surviving in water for longer duration and resist chlorination at doses normally used in water works practice. - Their presence indicates faecal contamination at some remote time.

14. 3. CHEMICAL ASPECTS a. Chlorides: All water contains chlorides. Since the chloride content of water varies from place to place, it is necessary to know the normal range of chloride, any excess above the normal range should raise suspicion of contamination. Normal value= 200-600mg/litre.

15. b. Hardness: Total hardness should not exceed 300 mg/litre. c. Free & Saline ammonia: This is an excellent indicator of sewage contamination of recent origin. Proteinaceous matter present in faecal matter is degraded and the resulting nitrogen is converted into bacterial action.

16. d. Albuminoid ammonia: It is measure of the decomposable organic matter, yet to be oxidized. Underground water should not contain albuminoid ammonia. In potable water it should not exceed 0.1 mg/liter. e. Nitrites: It should be zero in potable water, their presence indicates recent contamination. however in deep well, it is present normally due to reduction of nitrates by ferrous salts. Water, except deep well, containing nitrites should be viewed with suspicion.

17. f. Nitrates: Nitrates tell the chemical story of past history of water. - their presence indicates old contamination, provided nitrites are absent. - levels should not exceed 1 mg/liter. g. Oxygen absorbed: The amount of oxygen absorbed by water is regarded as an approximate level of the amount of organic matter present in water. It should not be more than 1 mg/L in 3 hours at 37deg. C.

18. h. Dissolved oxygen: Should not be less than 5 mg/L. i. Toxic Substances: Their presence above prescribed limits in water supply constitute grounds for rejection. They include - arsenic, cadmium,lead, mercury, cyanide and selenium.

19. POINT TO REMEMBER: Presence of ammonia, nitrites, nitrates & increase amount of oxygen absorbed indicates contamination.

20. 4. RADIOLOGICAL ASPECTS There is evidence from both human and animal studies that radiation exposure at low to moderate doses may increase the long-term incidence of cancer. Animal studies in particular suggest that the rate of genetic malformations may be increased by radiation exposure.

21. Acute health effects of radiation, leading to reduced blood cell counts and, in very severe cases, death, occur at very high doses of exposure of the whole body or large part of the body. Due to the low levels of radionuclides typically found in drinking-water supplies, acute health effects of radiation are not a concern for drinking-water supplies.

23. WATER QUALITY STANDARDS WHO ‘ International Standards For Drinking Water’ relate to 5 water quality variables. 1. Microbiological pollutants. 2. Toxic substances. 3. Specific chemical substances that may affect health. 4. Characteristics affecting the acceptability of water. 5. Radioactive substances.

24. 1. MICROBIOLOGICAL POLLUTANTS These are the standards relating to the presence of bacteria and viruses in drinking water. • STANDARD OF BACTERIAL QUALITY - Treated water- ideally all samples taken from distribution system should be free from coliform organisms. Following standards are recommended:

25. a. Throughout any year, 95% of samples should not contain any coliform organisms in 100 ml. b. No sample should contain E.coli in 100 ml. c. No sample should contain more than 10 coliform organisms per 100 ml. d. Coliform organisms should not be detectable in 100 ml of any two consecutive samples.

26. STANDARD OF VIRAL QUALITY The WHO standards fix the limit for viruses at one plaque forming unit (PFU). A Plaque Forming Unit (PFU) is a measure of the particles capable of forming plaques per unit volume such as virus particles.

27. 2. TOXIC SUBSTANCES The presence of following substances in excess of amount should constitute grounds for rejection of water as a public supply for domestic use:

29. 3. SPECIFIC SUBSTANCES THAT MAY AFFECT HEALTH A. FLUORIDES: Fluoride is essential constituent of drinking water. It should be more than 0.5mg/L. • DEFICIENCY: - deficiency causes dental caries • EXCESSIVENESS: - Excessive of fluorides in drinking water may give rise to dental fluorosis in children.

30. - When present in much higher amounts, it causes endemic cumulative fluorosis with resultant skeletal damage in both children and adults. B. NITRATES: Nitrates are dangerous to human health only in infants. - Excess amount can causes infantile methemoglobinemia.

31. C. AROMATIC HYDROCARBONS: Some polynuclear aromatic hydrocarbons (PAH) are known to be carcinogenic. • Concentration should not exceed 0.2 microgram/L

32. 4. SUBSTANCE AFFECTING ACCEPTABILITY OF WATER The following criteria have been suggested by WHO in assessing the potability of water:

34. 5. RADIOACTIVE SUBSTANCES Pollution of water supplies by radioactive substances represents an increasing hazards with regard to water quality. - Radioactivity is expressed as picocuries per litre (pCi/L) WHO has proposed the following limits of radioactivity as acceptable: • Gross alpha activity 3 pCi/L • Gross beta activity 30 pCi/L

36. SURVEILLANCE OF DRINKING WATER QUALITY

38. Surveillance of drinking water is essentially a health measure. It is intended to protect the public from waterborne diseases. The elements of surveillance programme are: 1. Sanitary Survey 2. Sampling 3. Bacteriological surveillance 4. Biological examination 5. Chemical surveillance

39. 1. SANITARY SURVEY: The sanitary survey is an on-the-spot inspection and evaluation of entire water supply system by a qualified person. PURPOSE: - To detect faults and correction of deficiencies.

40. 2. SAMPLING: Proper water sampling is very important step in surveillance of water quality. It should be done thoroughly and carefully according to standards of WHO. Sampling should be done for: a. Physical & Chemical Examination b. Bacteriological Examination

41. a. SAMPLING FOR PHYSICAL & CHEMICAL EXAMINATION: • Sample should be collected in CLEAN GLASS STOPPERED BOTTLE made of neutral glass. • Capacity of the bottle should not be less than 2 litres. • Stoppered glass bottle technically known as “Winchester Quart Bottle” are suitable.

42. WINCHESTER QUART BOTTLE

43. Before collecting the sample rinse the bottle well three times with the water filling it each time about ⅓ full. • Then fill it with water. • Tie the stopper tightly down with a piece of cloth over it. • Seal the string

44. b. SAMPLING FOR BACTERIOLOGICAL EXAMINATION: • It should be collected in clean sterilized bottle made of neutral glass of capacity 200-250 ml and provided with a glass stopper having an overlapping rim. • The stopper must be relaxed by an intervening strip of paper to prevent breakage of bottle during sterlization or jamming of bottle.

45. The stopper and neck of the bottle should be protected by a paper cover. • If the water to be sampled contains or is likely to contain chlorine, a small quantity of sodium thiosulphate (0.1ml of 3.0 % solution) should be added to the bottle before sterilization. • Sterile sample bottles should be obtained from the laboratory which is to carry out the analysis. • The sampling bottle should not be opened until the moment at which it is required for filling.

46. 1. COLLECTION OF WATER FROM A TAP: • When a sample is to taken from as tap in regular use, the tap should be opened fully. • Water should be run to waste at least for 2 minutes in order to flush the interior of nozzle and to discharge the stagnant water in the service pipe.

47. In case of the samples to be collected from taps which are not in regular use, tap should be sterilized by heating it either with a blow lamp or with an ignited piece of cotton soaked in methylated spirit, until it is unbearably hot to touch. • Then the tap should be cooled by allowing water to run to waste before the sample is collected.

48. The bottle should be held near the base with one hand and the stopper and paper cover over it removed together and held in the fingers. • The sample bottle should be filled from a gentle stream of water from the tap.

49. THINGS NOT TO DO • Avoid splashing. • The collection of samples from taps which are leaky should be avoided because the water might run down the outside of tap and enter the bottle causing contamination. • If this cannot be avoided special precautions should be taken to clean the outside of tap and to flame it sufficiently to ensure sterility.