Rainfall
is the main source of water to man. Water source can either be surface or
underground source eg
Surface Sources: Surface water include the following
(i). Rain water collected directly from roofs
(ii).
Water from rivers, ponds and lakes
(iii).
Run – off from natural catchments into natural or artificial lakes.
Surface
sources of water usually contain micro-organisms. As such, water from these
sources must be treated before drinking.
Underground Sources: Underground sources of water include:
Wells-
both shallow wells and deep wells’
Shallow
wells are mostly used in the rural areas. They are fed by rainfall on the
surrounding ground which may carry polluting matters from the surface. Lining
such wells provides a lot of security and safety to the consumers.
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Water levels underground.
Deep
wells: These wells derive their water from below the impermeable stratum. The
water here is relatively safe having being filtered on its way downwards.
Springs:
Spring water is water that has travelled through the ground and come to the
surface as a result of geological conditions. The water flows over an
impermeable stratum onto the ground surface.
Water Quality
Water Quality
Drinking
water must not only be safe and free from dangers to health, it must also be of
good chemical and physical quality so as to be acceptable to the people. NAFDAC
is supposed to ensure the quality of water consumed nationwide.
Rural Water Supply System
Well,
using rope and bucket’
Well,
equipped with a windlass
Well,
with hand pump and motorized pump. The hand pump is the reciprocating pump or
the type used in selling kerosene.
Urban Water Supply System
In order to meet the constant demand for water
supply in towns and cities the water supply scheme embarked on generally
comprises of the following.
Collection or Intake system (Dam): In this system,
a pump house is usually located close to a dam, while purification takes place
at the treatment plant. The treated water is pumped through large diameter
pipes to reservoirs located at suitable sites for distribution. These elevated
reservoirs supply by gravity. But because of distance some booster pumps are
used to boost supply pressure so that water can reach all supply outlets.
Purification System: Before city water supply system is
distributed, the purification must take place first. This involves he following
Aeration-
to remove dissolved gases.
Clarification-
to get rid of suspended materials so that the water becomes clear.
Filtration-
to remove particulate matters.
Disinfection-
using chlorine to destroy undesirable organisms in water to control odour and
eliminate hydrogen sulphide in water.
Transmission and Distribution System: The
transmission system consists of pipelines that conveys water from he treatment
plant to the reservoir.
The
distribution system is another complex network of pipelines to distribute water
from the reservoir to city houses, offices and fire hydrants. The pipes are
usually buried at least 30cm below the ground.
The
distribution reservoir is required to store excess water during the periods of
peak demands. They must be placed at higher elevation so as to supply by
gravity.
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