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While planning a water supply scheme, it is necessary to find out only the total yearly demand but also to assess the required average rate of flow and their variation.

Type of demand :

Water use varies from city to city depending upon the climatic, characteristics of environment, industrialization and other factors in the given city. Water use varies from season to season, day to day and hour to hour. Thus, planning the water supply scheme, the portable water use and its variation must be estimated as much as possible.

Following are the various types of water demand :

  1. Domestic water demand
  2. Institutional water demand
  3. Fire water demand
  4. Commercial water demand
  5. Demand for public use
  6. Compensate losses in water or waste water.

Per capita demand:

It is the annual average amount of daily water requirement by person and includes domestic use. IT is expressed in lit/day.

Per capita element= Total water requirement (litre)/365*designed population 

Factors affecting water use

  1. Dry climate
  2. Characteristics concern
  3. Environmental of population
  4. Industry and commerces
  5. Pressure in distribution system
  6. Water rates and metering

Problem no .1:

For this given information analysis the water supply situation of the given municipality also discusses the new project of meeting the demand upto 2085 B.S.

Name of municipality: Kritipur

Population= 120150( 2068 A.D.)

Population grow rate per year = 4.1%

Present situation of water supply 

S.N.Name of projectAmount of water (HCT)
1.Sundarighat ground water supply project5 million liter/day
2.Dudh pokhari water supply project5 million liter/day

After 2068 situation of water supply

S.N.Name of projectAmount of waterExpected comp
1.Melachmi water supply project10 million lit/day2075
2.Darighat ground water supply5 million lit/day2080

Capital demand = 135 lit/day/person by Kathmandu

For 2068, population = 120/50

Water demand= 120/50*135

= 16220250 lit/day

For 2071

PT= Po (1+R/100)T

      = 120/50(1+4.1/100)3

     = 135542.647

Water demand= 135543*135

= 18298305 l/day/person

For 2075

PT= PO(1+R/100)T

     = 135543(1+4.1/100)4

    = 159176.88

   = 159177

Water demand = 159177*135

    = 24488895 L/day/person

For 2080

PT= PO(1+4.1/100)T

    = 1591767(1+4.1/100)5

   = 194596.019

Water demand= 194596*135

= 226270460

For 2085

PT=PO (1+R/100)T

    = 194597(1+4.1/100)6

    = 237897

Water demand= 237897*135

= 32115960


As the population of Kritipur was increased by 4.1% each year. It is increasing at the rate of 4.1% . In the early days, the demand for water was very low compared to recent days.

Water supply is down mainly from rivers, lakes and groundwater. Water consumption varies widely from place to place. Water demand is directly proportional to the population . So, after 2068 two projects were launched to fulfill the demand for water .

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