DILLA UNIVERSITY

COLLEGE OF ENGINEERING AND TECHNOLOGY

Course: Water and Sewage (Arch-3232)

Section 1

By: Wubit S. (M.Sc.)

Email: wubit.seyoum@du.edu.et

March,2024
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 Contents:
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❖ Introduction

❖ Need for protected water supply

❖ Importance of water supply

❖ Sources of water

❖ Methods of Purification

✓ Preliminary water treatment (Intakes, screens, storage,

plain sedimentation, silt traps etc.)

✓ Primary water treatment (Sedimentation,

Coagulation/Flocculation, Filtration and disinfection)
 1. Introduction
3 Importance and necessity for planned water supplies

❖ Next to the air, the other important requirement for human, animals
and plants life to exists is water.

❖ Water is available in rivers, lake, streams etc.

❖ The earliest civilizations families have settled close to water sources

along banks of major river systems and required water for drinking,
domestic use, agricultural use, watering animals…

❖ In many countries people live in areas where water is scarce (E.g.

Sub-Saharan region in Africa), often woman and children carry it
over long distances, particularly during dry periods (scattered
population).
 Needs For Protected Water Supply
➢ Protected water supply means the supply of water that is treated
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to remove the impurities and made safe to public health.

➢ Water may be polluted by physical and bacterial agents

➢ It is also good carrier of disease causing germs. The causes of

outbreak of epidemics are traced to pollute water and poor
sanitation.

➢ However during the last few decades, there is improvements in

the public health protection by supplying safe water and
sanitation to all the people in the developing countries. In 1977,
united nations declare to launch a movement known as
“HEALTH FOR ALL BY THE YEAR 2000 A.D.
 Importance of water supply
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➢ It improve Hygiene and Health

➢ For meeting basic Socio-Economic development

➢ To use time and Energy savings by an improved water supply

➢ to make adequate provisions for emergencies like fire fighting,

festivals, meeting etc.

➢ to maintain the treatment units and distribution system in good

condition with adequate staff and materials

➢ to make provision for future demands due to increase in

population, increase in standard of living, storage and conveyance
etc.
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 TYPES OF WATER DEMANDS
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➢ While designing the water supply scheme for a town or city, it is
necessary to determine the total quantity of a water required for
various purposes by the city.

➢ Following are the various types of water demands of a city or town:

✓Domestic water demand

✓Industrial water demand

✓Institution and commercial demand

✓Demand for public use

✓Fire demand

✓Loses and wastes

8 As per IS: 1172-1963, water supply requirements for
the public buildings other than residences as
follows:
 FIRE DEMAND
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➢ Fire may take place due to faulty electric wires by short
circuiting, fire catching materials, explosions, bad intension of
criminal people or any other unforeseen mis happenings.

➢ If fires are not properly controlled and extinguished in

minimum possible time, it lead to serious damage and may burn
cities.

➢ Fire hydrants shall be installed at public and municipality

interest such as schools, shops, hospitals, fuel stations and at
salient points of distribution network.

➢ Empirical Formulas used to calculate FFD:

 FIRE DEMAND
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➢ Empirical Formulas used to calculate FFD:
 Factors Affecting Per Capita Demand
11 ➢ The following are the main factors affecting for capita demand of

the city or town:

➢Climatic conditions

➢Size of community/size of town

➢Living standard of the people

➢Industrial and commercial activities

➢Pressure in the distribution system

➢System of sanitation

➢Cost of water
 2. Sources of water
12 ➢ The water which goes to the atmosphere as vapor from the earth
which is then precipitated back in the form of rain, snow, hail,
dew, sleet or trust

➢ This precipitation and evaporation continues for ever. This

process is known as hydrological cycle of water
 Sources of water
13 ➢ All the sources of water can be broadly divided into
1. Surface sources
2. Sub surface sources
I. The surface water sources further divided into
1. Ponds and Lakes
2. Rivers or streams
3. Impounding Reservoirs
II. Sub Surface Sources are further divided into
1. Infiltration galleries
2. Infiltration wells
3. Springs
 Infiltration galleries

14 ❖ It is underground tunnel Which have holes on its sides, used for

tapping underground water near river, lakes or streams
 Infiltration Wells
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 Infiltration wells are the shallow wells constructed in series along
the banks of a river. In order to collect the river water seeping
through their bottoms.

 These wells are constructed of brick masonry with open joints.

They are generally covered at the top and kept open at the bottom.
 III. Types of springs
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➢ Sometimes ground water reappears at the ground surface in the
form of springs. Springs generally supply small quantity of water
and hence suitable for the hill towns. Some springs discharge hot
water due to presence of Sulphur and useful only for the curve of
certain skin disease patients
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 Water Quality Characteristics
18 Water source can be examine, the impurities present in water may
be divided into the following three categories:
1.Physical
Chemicalcharacteristics
Characteristics 2. Chemical Characteristics
 Turbidity Inter chemical analysis of water ; these tests are done that will reveal the
 Color sanitary quality of water. This involves tests for determining the total solids and
 Taste and odor suspended solids, PH value, hardness of water, chloride content etc
 Temperature, and 3. Biochemical Oxygen Demand
 Foam. If the water is contaminated with sewage , the demand of oxygen by organic
matter in sewage is known as biochemical oxygen demand
The examination of water for the presence of bacteria is important for the
water supply engineer from the view point of public health. The bacteria may be
harmless to mankind or harmful to mankind
 Methods of water treatment/Purification
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 One complete water treatment plant requires the following process starting
20 from the source of water up to the distribution zone of sequence
21 General flow chart for surface water
treatment
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Thank You For Your Attention!