SUB- Ws and Wwe
Topic-Introduction to water supply
5TH SEM
BY
ER. RAGHABENDRA MOHAPATRA
(Lect In Civil Engineering Department)
AY:2021-2022
Buston's formula-
q = 5663√p
where p in thousands.
here, p =100, q = 5663√100
Raw Water Source-
The various sources of water can be classified into two categories:
1. Surface sources, such as
a. Ponds and lakes;
b. Streams and rivers;
c. Storage reservoirs; and
d. Oceans, generally not used for water supplies, at present.
2. Sub-surface sources or underground sources, such as
a. Springs;
b. Infiltration wells ; and
c. Wells and Tube-wells.
Water Quantity Estimation
The quantity of water required for municipal uses for which the water supply scheme has to be
designed requires following data:
1. Water consumption rate (Per Capita Demand in litres per day per head)
2. Population to be served.
Quantity= Per capita demand x Population
Factors affecting per capita demand:
a. Size of the city: Per capita demand for big cities is generally large as compared to that
for smaller towns as big cities have sewered houses.
b. Presence of industries.
c. Climatic conditions.
d. Habits of people and their economic status.
e. Quality of water: If water is aesthetically & medically safe, the consumption will increase
as people will not resort to private wells, etc.
f. Pressure in the distribution system.
g. Efficiency of water works administration: Leaks in water mains and services; and
unauthorised use of water can be kept to a minimum by surveys.
h. Cost of water.
i. Policy of metering and charging method: Water tax is charged in two different ways: on
the basis of meter reading and on the basis of certain fixed monthly rate
Fluctuations in Rate of Demand-
2. Maximum daily demand = 1.8 x average daily demand
3. Maximum hourly demand of maximum day i.e. Peak demand-
= 1.5 x average hourly demand
= 1.5 x Maximum daily demand/24
= 1.5 x (1.8 x average daily demand)/24
= 2.7 x average daily demand/24
= 2.7 x annual average hourly demand
4.This quantity should be worked out with due provision for the estimated requirements of the
future .The future period for which a provision is made in the water supply scheme is known as
the design period.
1. Arithmetic Increase Method
2. Geometric Increase Method
3. Incremental Increase Method
4. Decreasing Rate of Growth Method
5. Simple Graphical Method
6. Comparative Graphical Method
7. Ratio Method
8. Logistic Curve Method