This document discusses sources and characteristics of safe drinking water. It outlines various water sources including rain, surface, and ground water. Surface water sources include rivers, reservoirs, and tanks, which often require treatment due to potential contamination. Ground water from deep wells tends to be cleaner than other sources. The document emphasizes the importance of providing communities with water that is free from contamination, adequate in quantity, and accessible throughout the year to support health and prevent water-related diseases. It also describes best practices for constructing sanitary wells to access ground water safely.

1. V.Lokeesan, BSN
T.Assistant lecturer
FHCS,EUSL.

2. Objectives
• Water
–Sources and characteristics
–Purpose of water, types of wells

3. Introduction
• Health care to a community cannot be provided
without ample and safe drinking water
• Health which affects humanity especially in
developing countries is due to lack of safe and
wholesome water
• Water that is easily accessible, adequate in quantity,
should be free from contamination, safe and readily
available throughout the year.

4. Safe and wholesome water
 Free from pathogenic agents
 Free from harmful chemical substances.
 Pleasant to taste i.e., free from colour and odour
and
 Usable for domestic purposes
Water is said to be polluted or contaminated
when it does not fulfill the above criteria.

5. Water requirement
• The basic physiological requirements for drinking
water has been estimated at about 2 liters per head
per day.
• A daily supply of 150 – 200 liters per capita is
considered as an adequate supply to meet the needs
for all urban domestic purposes.
• Water should be made available in adequate volume
to reduce the incidence of water related diseases.

6. Uses of water
The uses of water include:
1. Domestic use: Drinking, cooking, washing, bathing,
flushing of toilets, gardening etc.
2. Public Purposes: Cleaning streets, purposes like
swimming pools, public fountains, ornamental ponds,
fire protect and public parks.
3. Industrial Purpose: Processing and Cooling.
4. Agriculture Purpose: Irrigation
5. Power Production: from hydropower and steam
power
6. Carrying of waste: through drainage.

7. Sources of water supply
There are three main sources of water
1. Rain water
2. Surface water
– Impounding reservoir
– Rivers and streams
– Tanks, ponds and takes
3. Ground water
– Shallow wells
– Deep wells
– Springs

8. Rain water
Rain is the prime source of all water.
Rain water is the purest in nature:
– Physically - it is clear, bright and sparkling.
– Chemically - it is very soft containing traces of dissolved
solids.
– Bacteriologicaly – it is clean and free from pathogenic
agents.
The amount of rain water collected will depend
upon the rainfall. 1 cm of rainfall over, 1 sq.m will
yield 10 liters of water.
Rain water needs to boiled or disinfected if used for
drinking.

9. WATER CYCLE

10. Surface water
• Surface water originates from rain water. It is the
main source of water supply in many areas.
• Examples of surface water include rivers, tanks,
lakes, man – made reservoirs and sea water.
• Surface water is prone to contamination from
human and animal sources.
• Surface water needs purification before use for
drinking and cooking purposes.

11. Impounding reservoirs
• These are artificial lakes constructed usually of
earthwork or masonry in which large quantities of
surface water is stored.
• Dams built across rivers and mountain streams also
provide large reserves of surface water.
• The area draining into the reservoir is called
“catchment area”.
• The disadvantage of storing water is the growth of
algae and other microscopic organisms, which impart
bad tastes and odors to water.

12. IMPOUNDING RESERVOIRS [cont...]
Characteristics
• Impounding reservoirs usually furnish a fairly good
quality of water.
• The water is usually clear, palatable and ranks next to
rain water in purity.
• The water is usually soft and considered tobe free of
pathogenic organisms.
Impurities
• The upland surface water derives its impurities from the
catchment area, the sources being human habitations
and animal keepig or grazing.

13. Rivers
Characteristics
• River water is turbid during rainy season; it may be
clear in other seasons.
• Clarity of water is no guarantee that river waer is
safe for drinking.
• It contains dissolved and suspended impurities of all
kinds.
Impurities
• The impurities of river water are derived from
surface washings, sewage and sullage water,
industrial and trade wastes, and drainage from
agricultural areas.

14. Tanks
• Tanks are large excavations in which surface water
is stored.
• They are an important source of water supply in
some parts of the country.
• Tanks are recipients of contamination of all sorts.
They are full of silt and colloidal matter, especially
after the rains.
• Older tanks may be full of aquatic vegetation.

15. Ground water
• Rain water percolating into ground water constitutes
ground water.
• Ground water is the cheapest and most practical
means of providing water to small communities.
• Ground water is superior to surface water, because
the ground itself provides an effective filtering
medium.

16. Ground water [cont...]
ADVANTAGES DISADVANTAGES
It is likely to be free from
pathogenic agents
It is usually requires no
treatment
The supply is likely to be
certain even during dry
season
It is less subject to
contamination than
surface water.
It is high in mineral
content .
It requires pumping or
some arrangement to lift
the water.

17. Wells
• Traditionally wells are the common and main source
of water supply in most areas.
• Technically wells are of two;
i. Shallow wells- tap subsoil water
ii. Deep wells- taps water from the water bearing
stratum

18. Shallow well Deep well
Definition Taps the water from
above the first
impervious layer
Taps the water from
below the first
impervious layer
Chemical quality Water is moderately
hard
Much harder
Bacteriological
quality
Often grossly
contaminated
pure water
Yield Dry in summer Constant supply

19. Classified according to method of
construction
• Dug wells
• Tube wells

20. Sanitary well
• This is a well that is properly located, suitably
constructed and well protected from contamination,
thus supplying safe water.
• The following important points are to be taken into
consideration in constructing safe wells:
i. Location
ii. Lining
iii. Parapet
iv. Platform
v. Drain
vi. Covering
vii. Hand-pump

21. Sanitary well [cont…]
• Location
– Should be away not less than 15m from sources of
contamination
– Distant between well and the house (<100m)
• Lining
– Lining should be built of bricks or stones set in cement up
to 6 m deep, to allow the water to enter from the bottom
and not from the sides of the well.
– Lining should be curried 60-90cm above the ground

22. Sanitary well [cont…]
• Parapet wall
– A parapet wall around the well up to the height of at least
(70-75 cm) should be provided above the ground.
• Platform
– Along with the parapet wall the platform should be made
with cement concrete extending at least 1m in all
directions.
– It should have gentle slope outward leading to a drain
built along its edges.

23. Sanitary well [cont…]
• Drain
– A pucca drain should be built to collect the spilt and dirty
water from the platform of the well and this should be
channeled to a drain or soak pit that is away from the
well.
• Covering
– The top of the well should be covered well by a cement
concrete cover to avoid direct contamination.

24. Sanitary well [cont…]
• Hand-pump
– A good sanitary well should be equipped with a hand
pump to lift the water in a clean manner.
– When such a facility is not available, it is desirable to
attach a chain and a bucket to the well for the common
use.

25. Springs
• Ground water comes to the surface and flows
freely under natural pressure
• Two types
– Shallow springs
– Deep springs

26. REFERENCES
Park,K.(2010). “ Park’s Textbook of Preventive
and Social Medicine”. Ed 20. Bhanarsidoss
Bhanot Publishers, Jabalpur, India.
Rao, K.S. (2004). “An Introduction to
Community Health Nursing”. Ed 4. B.I.
Publications Pvt. Ltd, Chennai, India.