1.1 Importance of Water:

Water is an essence of life. Human, animals, and plants require water for their survival. Seventyone percent of the surface of the earth is covered by water. Five percent of water loss in the body causes degradation of the muscle strength and endurance. 10% reduction in water leads to delirium and blurred vision and 20% reduction in water leads to death.

Functions of water in human body:

Importance of Water supply Engineering:

•Aesthetic appearance 1.2 Definition of Types of Water:

Water which does not contain any other substances except Hydrogen and Oxygen is said to be pure water. Pure water is note actually suitable for drinking as it lacks vital minerals required for human growth. Pure water is used in laboratories and medical purposes and is obtained by the special method of distillation.

Water that contains other substances as mineral salts, organisms, gases except hydrogen and oxygen is called impure water. The water that is used for drinking is impure water, but impurities should not be excessive to cause an adverse effect on human health.

1.2.2 Potable and Wholesome Water:

Water that is safe for drinking by humans and other animals is called potable water. It is also called safe water.

Water that is practically clear, colourless, odourless, palatable, sparkling and reasonably free from objectionable chemical salts in solution and from microscopic organisms in suspension is called wholesome water.

Requirements:

Physical quality: Including colour, taste and odour.

1.2.3 Polluted and Contaminated Water:

The water that contains excessive impurities as minerals, salts, gases, microorganisms is called polluted water. The polluted water is not generally clean and wholesome.

The water that contains microorganisms such as bacteria, virus, protozoa, and worms is called as contaminated water. It is non potable and must not be used for drinking purposes.

1.3 Historical Development of Water Supply System:

The process of supplying potable water from source to consumers through the network of pipes, reservoir, and other appurtenances is known as water supply system or water supply scheme. Digging of shallow wells was the earliest innovation beyond rivers, lakes, and springs.

•Use of cast iron pipes with joints started in the 19thcentury.

Rural Water Supply and Sanitation Fund Development Board (RWSSFDB) Source : PPTA No. 4972-NEP

 Functions

Water Supply Promotion

Promotion of local development and decentralization

Overall development of education in the country

Designing and construction of school infrastructures (water supply and sanitation)

 Implements the water resource policies.

Fixes water tariffs and ensures quality standards in service delivery.

Responsible for the provision of drinking water in designated municipalities.

Fund Implements projects through a system of technical support agencies.

Develops technical standards

Job:

1.6 Schematic Diagrams of Typical Water Supply System:

The layout of water supply system and its component extending from the water source to the consumer areas is called schematic diagram of a water supply system.

Intake > Sedimentation Tank > Disinfection > Distribution

Fig: Rural water supply scheme

Intake > Reservoir > Sedimentation Tank > Sedimentation with coagulation > Filtration > Disinfection > Hardening/Softening > Aeration > Storage tank > Distribution

Fig: Urban water supply scheme

1.7 Components of water supply system:

Intake: A device or a structure constructed at the water source for the purpose of drawing water from the source and conveying to the other components of the water supply system is termed as intake.

Pump: It is a device to lift the water from the source. Pumping is required when the consumer area is at the higher elevation than the source. It should be avoided as far as possible to minimize the cost.

Transmission main: It is a pipe laid to convey water from source to reservoir. It is designed for the flow equivalent to the maximum daily demand. The transmission main and all other components located in it are designed for the average flow as daily peak factor is considered to be one in Nepal.

Collection Chamber: Collection chamber is provided either at the intake or near the intake site to collect the water from one of more sources. It breaks the incoming water pressure into atmospheric pressure which prevents the backflow of water from one source to another.

Distribution Chamber: It is a tank provided at the junction of the pipeline when water has to be conveyed in more than one direction at atmospheric pressure.

Interruption Chamber: It is a tank present in the transmission main to break the excessive internal water pressure built in the pipeline.

Reservoir: It is a tank or a basin which is used to store water. It may be classified as clean water reservoir and service reservoir. Clean water reservoir stores water after treatment has been done and is used for water supply purposes. Service reservoir stores water that is used for firefighting purposes.

Distribution System: Distribution system is a network of pipeline that conveys the water from the service reservoir to the consumer. It is designed for maximum or peak flow.

Break Pressure Chamber (BPC): It is a tank that is located in the distribution system to break the excessive internal water pressure built up in the pipeline. It reduces the cost as it avoids the necessity of high-pressure rating pipes. It is provided with the float valve.

Public Stand Post (PSP): It is a structure in the pipeline (usually in the rural water supply system) from where water is distributed to the consumers.

Valves: Valves are appurtenances provided in the pipeline to control and regulate the flow of water, to prevent the flow in opposite direction, to release the excessive pressure and to conduct other functions.

Valve Chamber: The chamber in which one or more valves are located is called a valve chamber.

Fittings: Fittings are those appurtenances that allow pipes to be joined or installed in the appropriate place and closed where necessary.

Bibliography:

Kansakar B.R. (2015), Water Supply Engineering, Divine Print Support, Lagan Tole, Kathmandu.

Punmia B.C., Jain A. and JainA. (1998), Water Supply Engineering, Laxmi Publications (P) Ltd., New Delhi, India