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Introduction to Water Supply

Importance of Water
Water is an essence of life. Human, animals, and plants require water for their survival. Seventy-one 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
    • It moisturizes the air in lungs and joints
    • It helps in metabolism
    • It protects our vital organs
    • It transports oxygen and nutrients into cells
    • It regulates human body temperature
    • It helps to absorb nutrients
  • Importance of Water supply Engineering:
    • Necessity of life
    • Prevention of land pollution
    • Aesthetic appearance

Definition of Types of Water

  • Pure and Impure 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.
  • 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 are:
    • Biological Quality
      Including the levels of bacteria and viruses.
    • Chemical Quality
      Including the levels of metals, pesticides, solvents and hydrocarbons.
    • Physical Quality
      Including colour, taste and odour.
  • 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.

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.
  • Brick lined wells were built by city dwellers in the Indus River basin as early as 2500 BC and wells almost 500m deep are known to have been used in ancient China.
  • Use of cast iron pipes with joints started in the 19th century.
  • Stone spouts were introduced to the Kathmandu valley during the Lichhavi period, in the fifth to seventh centuries.
  • There are 118 stone spouts in Kathmandu, 103 in Bhaktapur and 48 in Patan.
  • Bir Dhara System was commissioned in 1895 A.D.
  • Pani Goshowara Adda was established.
  • Department of Water Supply and Sewerage (DWSS) were formally established in 1972.

Water Supply Sector Institutions in Nepal

Ministries Urban Development (MoUD)
Local Development (MLD)
Water Resources (MWR)
Education and Sports (MoES)
Health and Population (MoHP)
Government Departments Department of Water Supply and Sewerage (DWSS)
Department of Urban Development and Building Construction (DUDBC)
Department of Local Infrastructure Development and Agriculture Roads (DoLIDAR)
Government Bodies Water Supply Tariff Fixation Commission (WSTFC)
Town Development Fund (TDF)
Nepal Water Supply Corporation (NWSC)
Kathmandu Upatyaka Khanepani Limited (KUKL)
Local Government District Development Committees (DDC)
Municipalities
Village Development Committees (VDC)
NGOs Nepal Water for Health (NEWAH)
Water Aid Nepal
Environment and Public Health Organization (ENPHO)
Federation of Drinking Water and Sanitation Users Nepal (FEDWASUN)
Others Urban Development through Local Efforts
Urban Environment Improvement Project
Public Private Partnership for Urban Environment
UN-Habitat-Nepal
World Health Organization (WHO)
United Nations International Children Education Fund (UNICEF)
Rural Water Supply and Sanitation Fund Development Board (RWSSFDB)

Source : PPTA No. 4972-NEP

Sectors Functions
Ministry of Urban Development (MoUD)  Water Supply Promotion
Ministry of Local Development (MLD) Promotion of local development and decentralization
Ministry of Education and Sports (MoES) Overall development of education in the country
Designing and construction of school infrastructures (water supply and sanitation)
Ministry of Water Resources (MWR) Implements the water resource policies.
Water supply Tariff Fixation commission (WSTFC) Fixes water tariffs and ensures quality standards in service delivery.
Nepal Water Supply Corporation (NWSC) Responsible for the provision of drinking water in designated municipalities.
Rural Water Supply and Sanitation Fund Development Board (RWSSFDB) Implements projects through a system of technical support agencies.
Department of Water Supply and Sewerage (DWSS) Develops technical standards
Construction of sanitation facilities
Coordination of health and hygiene education
Designs and constructs activities for water supply and sanitation

Objectives of Water Supply System

  • Qualitative water supply (safe, wholesome and potable water)
  • Quantitative water supply
  • Efficient water supplies scheme
  • Affordable water supply
  • Accessible water supply
  • Continuation
  • Reliable water supply
  • Water supply for industrial, commercial and domestic purposes.

Job

  • Collection of water
  • Transmission of water
  • Treatment of water
  • Distribution of water

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.

  • Rural Water Supply Scheme
    Intake > Sedimentation Tank > Disinfection > Distribution
  • Urban Water Supply Scheme
    Intake > Reservoir > Sedimentation Tank > Sedimentation with coagulation > Filtration > Disinfection > Hardening/Softening > Aeration > Storage tank > Distribution

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.

 


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