This document provides an overview of water supply and waste water management. It discusses the components of a water work scheme, including collection works like dams and tube wells, treatment works, transmission works, and distribution works. It also defines design period as the number of years in the future that a water supply facility is designed to meet demand. Factors that affect design period include the useful life of structures, population growth rate, ease of extension, lead time, economy of scale, and performance time.

1. CE-345 water supply and waste water Management
Lecture# 01
(6th semester civil)
By: Engr. Hayat Hussain
Lecturer Saidu polytechnic institute saidu sharif Swat

2. Contents
Water supply
Components of water work scheme
Design period
Factors affecting design period

3. Water supply
THE PROCESS OF SUPPLYING WATER TO A COMMUNITY IN ADEQUATE
QUANTITY AND QUALITY.

4. Components of water work scheme
• Collection works
• Treatment works
• Transmission works
• Distribution works

5. • Collection works
In collection works, water is collected from the source. There are two
major source of water. Surface water and ground water. In order to
collect surface water, dams and barrages are constructed whereas to
collect ground water, tube wells are used.

6. • Treatment works
In treatment works, water obtained through the source is treated. Most
of the surface water need treatment as it is contaminated by suspended
particles. Ground water may or may not need treatment. One of the
problems with ground water is high salt concentration. It is more
expensive to treat this. In such case surface water is used, when ground
water contains high salt concentration. Ground water may also contain
elements like iron, magnesium.

7. • Transmission works
If source of water is away from the community, transmission work is
required to transport water the treatment plant and then the treated water
from treatment plant to the community. In some cases, transmission
work may be eliminated

8. • Distribution works
In Distribution works, treated water is supplied to the consumers at the
point of use from overhead tanks.
Following two requirements should be fulfilled while distribute water to
the community
1. Quantity of water must be sufficient according to demand.
2. Pressure should be sufficient.

9. Design period
It is the number of years in future for which the proposed facility would
meet the demand of the community.
OR
The number of years in future for which supply will be more than
demand.

10. Factors affecting Design period
• Useful Life of the structure
• Rate of population growth
• Ease or difficulty in extension
• Lead time
• Economy of scale
• Performance time

11. • Useful Life of the structure
Life of structure is the number of years in future for which the design
period is physically suitable to provide the intended facility. So it
should be less than life of structure.

12. • Rate of population growth
If the rate of population growth is higher, then for that region shorter
design period is required.

13. • Ease or difficulty in extension
For the projects whose extension is easily possible, it is kept low. For
example we can install new tube wells at any time, so we do not need to
install all tube wells which would be required after 20 years. But for the
projects whose extension is difficult, their design period is kept greater.
For example dams and reservoirs cannot be extended easily.

14. • Lead time
it is the time from the commencement of a project to its completion.
Design period should be greater than lead time.

15. • Economy of scale
The decrease in average cost as the size of facility increase is known as
economy of scale. If the economy of scale is small, smaller design
period will be used. It is economical to build a large structure, for longer
design period.

16. • Performance time
Structures are checked under working condition for sometime, which
should not be considered in design period. During this time it is not
providing facility to community.

17. Questions & Answers

18. THANKS