USEFUL for MBBS students

2. Health: A state of complete physical, mental and
social well-being and not merely the absence of
disease or infirmity (WHO, 1948)
Environment: All that which is external to
individual human host. It can be divided into
physical, biological, social and cultural
components; any or all of which can influence
health status in populations.’ (WHO, 1995)

3. Disease result from complex interaction between
man, an agent and the environment.
From ecological point of view disease is defined as
“maladjustment of the human organism to the
environment”.

4. ENVIRONMENT
AGENT HOST
Health is a state of dynamic equilibrium between man and his
environment and when this equilibrium is disturbed, ill-health
(disease) occurs’.

5. PHYSICAL: air, water, soil, housing, geography, light,
noise, radiation, meteorological env etc.
BIOLOGICAL: man, viruses, microbial agents,
insects, rodents, animals and plants etc.
SOCIAL: occupation, literacy, income, religion,
standard of living, availability of health services, social
and political organizations etc.
CULTURAL: knowledge, attitudes, beliefs, practices,
cultural values, customs, habits, morals etc.

6. Biological (water, food, vector born ds)
Chemical (tobacco, pesticides, lead)
Physical (heat, humidity, radiation)
Psychological (anxiety, depression)
Sociological (overcrowding, riots)

7. WATER

8. Water is a prime natural resource, a basic human need --70%
of our body weight is due to water only.
Water is essential for drinking, cooking, washing, domestic
sanitation and industries
Environmental Hygiene Committee recommends
 minimum of 135 lit per capita per day (lpcd)
 For rural area: 40 lpcd
 for cities with piped water supply: 70 lpcd
 for megacities: 150 lpcd

9. Sources of Water
Rain water Surface water
Lake Dam
Underground Water
Water Spring Well
Sea water

10. A properly located,
well constructed and
protected vs contamination
and gives safe water
at least 50 ft away from
likely source of
contamination
2-3 ft wide cemented
platform around parapet
with sloping outwards
A cemented drain is made
around platform to drain
spilled water

11. Rainwater Harvesting
To preserve and buildup underground water reserves
1. Water harvesting tube well
2. Construction of dam and canals

12. The health hazards of water pollution may be classified as
Biological, Chemical and Radiological
Diseases related to water supply and caused by biological
agents are:
1. Water borne diseases
2. Water washed diseases
3. Water based diseases
4. Water related diseases

13. Caused by the ingestion of water contaminated by
human or animal faeces or urine containing
pathogenic microorganisms
Cholera
Typhoid
Amoebic/ Bacillary dysentery
Viral hepatitis
Leptospirosis
Giardiasis

14. Diseases due to lack of water. Poor personal
hygiene favours its spread.
Scabies
Skin sepsis & ulcers
Yaws
Trachoma
Conjunctivitis
Lice and Tick- borne diseases

15. Transmitted by insect vectors which breed in water
Malaria
Dengue fever
Filariasis
Chikungunya
Japanese encephalitis

16. Caused by parasites found in intermediate
organisms living in water.
An essential part of life cycle of agent takes place
in aquatic animal eg snails, Cyclops etc
Schistosomiasis
Dracunculiasis

17. Fluoride:
o deficency(<1mg/l): dental caries
o Excess: dental fluorosis
skeletal fluorosis
Iodine: goiter
Nitrates: excess –infantile methemoglobinemia
Salts of lead, iron, Zinc: constipation, colicky abdomen,
lead poisoning
Dissolved organic impurities (sulphates,chlorides)
:diarrhea and gastric disturbances

18. Water is defluoridated by phosphate to
reduce flourides to optimum levels.
Nalgonda Technique: addition of lime and
alum in sequence followed by flocculation,
sedimentation and filtration
Use of fluoride toothpaste in areas of
endemic fluorosis is not recommended for
children upto 6 years of age

19. If fluoride content of water is less than 0. 5
ppm then it is associated with dental caries
Flouridation is the process of supplementing
the natural fluoride content of potable
waters to the point of optimum
concentration

20. Hardness of water : soap destroying power
caused mainly by four dissolved compounds
1. Calcium bicarbonate
2. Magnesium bicarbonate
3. Calcium sulphate
4. Magnesium sulphate
Hardness is expressed in terms of mEq/L. One
mEq/L of hardness producing ion is equal to 50
mg CaCO3 in one litre of water

21. Grades of Hardness
1. Soft water : <1 mEq / L
2. Moderately Hard : 1-3 mEq / L
3. Hard Water : 3-6 mEq / L
4. Very Hard Water : >6 mEq / L
Impact :
 encrustation of the water carrying system, heating
utensils resulting (fuel wastage),
 Vegetables cooked in very hard water may be less
digestible
 reduces the life of fabrics.

22. Temporary Hardness : This can be removed by
boiling, addition of lime, addition of sodium
carbonate or by permutit process.
Permanent Hardness : This can be removed by
addition of sodium carbonate or by base exchange
process

23. It is used in treatment of large water
supplies
Sodium permutit is a complex compound of
sodium, aluminium and silica.
It has the property of exchanging the
sodium for the calcium and magnesium.
By this process, water can be softened to
zero hardness.

24. This occurs due to pollution of water supplies by
radioactive substances
Malignant diseases are the most important delayed
somatic effect.
The WHO has proposed the following limits of
radioactivity as acceptable :
● Gross alpha activity 3 pCi/l.
● Gross beta activity 30 pCi/l.

25. To protect water from being
contaminated, Parliament in
1974 passed
the water (Prevention and
control of pollution) act.
It provides legal deterrent
against the spread of
water pollution.
It also recommends the
constitution of Central and
State Water Boards endowed
with wide powers for
controlling pollution.

26. Guidelines for quality of drinking water on
various parameters
1. Acceptability Aspects
2. Microbiological Aspects
3. Chemical Aspects
4. Radiological Aspects

27. Acceptability Aspects

28. • Turbidity: should be less than 5 NTU (Nephelometric
Turbidity Unit)
• Colour: may be due to presence of organic matter or
minerals. Limit is 15 TCU
• Taste and Odour: may be due to minerals, presence of
organic matter or due to excessive residual chlorine in
treated waters
• Total Dissolved Solids: The guideline value for TDS is to
be below 1000 mg/litre
• pH: Guideline value for of water is 6.5 to 8.5
Acceptability Aspects

29. Bacterial Aspect
Coliforms: as indicators of faecal pollution in water
Faecal Streptococci: evidence of recent faecal
pollution of water
Clostridium perfringes:
 survive longer time and resist chlorination at the
doses normally used for disinfection.
 indicates remote time faecal contamination

30. Ideally, all samples taken from the distribution
system should be free from coliform organisms.
95 percent of samples should not contain E Coli
organisms in 100 ml water sample taken during 12
months period
No consecutive samples should contain coliform
organisms in 100 ml of water samples
In the case of waters from wells and springs, the
coliform count should be less than 10 per 100 ml

31. Viral Aspect
• Enteroviruses, reoviruses and adeno-virus
• As per WHO standards not more than one plaque
forming unit per liter of water is considered potable.
• There should also be complete absence of
enteropathogenic viruses and faecal bacteriophages.

32. Organic Constituents
Guidelines for Chlorinated
Hydrocarbons for Humans
(microgram/lit)
Dieldrin 0.03
Chlordane 0.2
DDT 2
Hexachlorobenzene 1
Lindane 2
Methoxychlor 20
Pentachlorophenol 9
Inorganic chemicals of health
significance in drinking water
maximum limit (mg/lit)
Antimony 0.005
Arsenic 0.01
Barium 0.7
Copper 2
Fluoride 1.5
Lead 0.01
Mangenese 0.5
Nitrate 50

33. Purification of Water
• Purification of Water on
a Small Scale
• Purification of Water on
a Large Scale

34. 1. Boiling:
kills all bacteria, viruses, spores, cysts and ova when the
water is boiled for 5 to 10 min of “rolling boil”
removes temporary hardness
The taste of water is, however, altered.
no residual protection against subsequent
contamination.
2. Chemical Disinfection
chlorine solution, bleaching powder, chlorine tablets or
iodine solution.

35. 3. Filtration
It is done through ceramic filters such as Pasteur
Chamberland, Berkefeld and Katadyn filters. Now
a days, UV radiation and RO system.

36. Chlorination with bleaching powder is the most
effective and cheapest method for this purpose.
1. Estimate quantity of water(by volume of well)
2. Estimate amount of bleaching powder required by
Horrock’s test.
3. make thin paste of bleaching powder in a bucket
and fill it three-fourth with water.
4. Transfer Supernatant clear solution another
bucket.
5. Lower This bucket into the well.
6. Leave for half an hour’s contact,
7. Do orthotoluidine test for adequacy of
chlorination

37. The components of a typical water
purification system comprise one or all of
the following measures:
Pretreatment
Filtration
Disinfection

38. The sub-steps included in pre-treatment are
1. Storage
2. Coagulation
3. Rapid Mixing
4. Flocculation
5. Sedimentation

39. Removes 98-99 per cent of bacteria
Slow sand filter: Biological
Rapid sand filter: Mechanical
Gravity & Pressure type

40. Slow Sand Filter

41. Rapid Sand Filter

42. Disinfection of water means making it fit for
drinking by destroying all pathogenic organisms
that may be present in it.
1. Physical methods : thermal treatment and
ultrasonic waves
2. Chemical: oxidising chemicals such as chlorine and
its compounds, bromine, iodine, ozone, metals like
silver
The disinfection action of chlorine is mainly by
hypochlorous acid and partly by hypochlorite ion.
Cl2 + H2O ↔ HOCl + H+ +Cl-

43. Break Point Chlorination

44. The International Drinking Water Supply and Sanitation
Decade 1981-1990
In India, under this program the laid down target was
100 percent safe water supply
1972-73: Accelerated Rural Water Supply Programme
1986: Technology Mission on Drinking Water
1992: Rajiv Gandhi National Drinking Water Mission
1999: Department of Drinking Water Supply was
formed under the Ministry of Rural Development
2003: Swajaldhara programme

45. Thank
you

46. Q. Which of the following is considered an
adequate water supply/capita/day in urban
areas
(a) 50-100 L
(b) 100-150 L
(c) 150-200 L
(d) 200-250 L

47. Q. Which one of the following is not a
waterborne disease :
(a) Kala azar
(b) Poliomyelitis
(c) Giardiasis
(d) Cholera

48. Q. Hardess of drinking water should be
a) <1 mEq / L
b) 1-3 mEq / L
c) 3-6 mEq / L
d) >6 mEq / L

49. Q. Which of the following compound gives
permanent hardness to water
a) Magnesium bicarbonate
b) Calcium sulphate
c) Calcium bicarbonate
d) Magnesium chloride

50. Q. Purest water in nature is from
(a) Lakes
(b) Springs
(c) Rains
(d) Ponds

51. The vital layer of the slow sand filter is also
known as :
(a) Superficial layer
(b) Sand bed layer
(c) Biological layer
(d) Chemical layer

52. The disinfecting action of chlorine is mainly
due to
(a) Chloride atom
(b) Hypochlrous acid
(c) Chloride ion
(d) Hypochlorite ion

53. Action of chlorine is maximum when water
pH is around
(a) 3
(b) 5
(c) 7
(d) 9

54. Chlorination does not affect in normal doses
(a) Salmonella
(b) Polio
(c) Shigella
(d) Vibrio

55. Minimum recommended concentration of
free residual chlorine is
(a) 0.1 mg/L
(b) 0.5 mg/L
(c) 1 mg/L
(d) 1.5 mg/L

56. ‘Problem Village’ is all except
(a) no safe water is available within
distance of 1.6 Km
(b) no safe water is available up to depth of
15 m
(c) no water harvestation is available
(d) drinking water contains toxic elements