Quantity of water
While designing the water supply plan, it is necessary to determine the total quantity of water required for various purposes according to the city or town. The amount of water required depends on the following two factors:
1. Estimated potential population at the end of the design period.
2. Rate of water consumption per person per day.
The period for which water supply projects are designed is known as the design period. The design period for water supply project is taken as 20 to 30 years which is required for the design purposes and gives very good results.
As per Indian Standards (IS: 1172-1963), the consumption of water for domestic purposes under normal circumstances is 135 liters per person per day. This is about 50% of the total consumption per person per day. The requirement of water for commercial and industrial purposes can be up to 50 liters per person per day which is about 20 to 25% of the total consumption of the city. Water consumption for nursing homes, schools and hostels is 135 liters per person per day.
The quantity of water are required to extinguish the fire should not exceed 5 to 10% of the total demand of the city. The following empirical formula relations are used to determine the demand (Q) of fire in liters per minute:
(a) National board of fire under writers formula : According to this formula,
𝑄 = 4637√𝑃[1 − 0.01√𝑃⦐
where P = Population in thousands.
(b) Freeman’s formula : According to this formula,
(c) Kuichling’s formula : According to this formula,
𝑄 = 3182√𝑃
(d) Burton’s formula : According to this formula,
𝑄 = 900√𝑃
(e) Buston’s formula : According to this formula,
𝑄 = 5663√P
Quantity of Water supply
requirements(According IS1172:1993)
Water supply for residences
In addition to non-domestic needs such as flushing requirements, a minimum of 70 to 100 liters per person per day may be considered sufficient for the domestic needs of urban communities.
The following rates per person quantity of water per day for a normal household and non-domestic needs may be considered as minimum:
(a) 40 lphd (minimum) water supply for communities up to 20,000 and without flushing systems.
(b) Water supply from 70 to 100 lphd (Litre per person per hour per day) through house service connection.
(c) Complete flushing system 100 to 150 lphd simultaneously for communities with population of 20,000 to 100,000.
(d) Full simultaneous flushing system 150 to 200 lphd for communities with a population of more than 100,000.
Note- The cost of supply of quantity of water a day from 150 to 200 liters per person per day for households for Low Income Group (LIG) and Economically Weaker Section (EWS) of the society will be reduced to 135 liters per person per day depending on the prevailing circumstances. can go.
Out of 150 to 200 liters per head per day, 45 liters per head per day can be taken for flushing needs and the remaining quantity can be taken for other domestic purposes.
Individual facility accommodations should have at least the following fitments:
(a) a shower room provided with a tap,
(b) a water closet, and
(c) Raised from a shower or sink or 1 floor.
Water Requirements for buildings other than houses Type of consumption Per day, in liters :
(i) Factories which require bath room are required to be provided 45 per person
(ii) The factories which do not require bathroom, need to provide 30 per person
(ii) Hospital (including laundry):
a) 340 per head if the number of beds does not exceed 100
b) 450 per head if the number of beds is more than 100
(iv) 135 per person in nurses' home and medical quarters
(v) Hostel 135 per person
(vi) Hotel 180 per person
(vii) Office 45 per person
(viii) Restaurant 70 per seat
(ix) Cinemas, Concert Halls and Theaters 15 per seat
(x) School:
a) day school 45 per person
b) Boarding school 135 per person
Note- See IS 9668: 1981 for fire requirements in buildings.
Where only one cistern is provided in a dwelling, the bath and cistern shall be kept separately.
Note- The water-closet, unless otherwise indicated, shall be of Indian style (squatting type).
water supply
Requirements for water supply as per the following
Nature of station where bathing facilities are provided litres/per person:
(a) railways, bus stations and ports
i) Intermediate Stations (Except Mail and Express Stops) 45
ii) Junction station and intermediate station where mail or express stoppage is provided 70
iii) Terminal Station 45
(b) airport
international and domestic airports 70
Nature of station where bathing facilities are not provided litre/per person:
(a) railways, bus stations and ports
i) Intermediate Stations (Except Mail and Express Stops) 25
ii) Junction station and intermediate station where mail or express stoppage is provided 45
iii) Terminal Station 45
(b) airport
international and domestic airports 70
Notes :
1. The number of persons shall be determined by the average number of passengers operated by the station per day; Due consideration may be given to the employees and vendors likely to use the facilities
2. Seasonal average peak requirements should be considered.
Quantity of water volume estimation
The following data is required while preparing a plan to give the quantity of water required for water supply:
Water consumption rate (per capita demand in liters per person per day)
served to the population.
Quantity of water formula
Quantity = Per capita demand x Population
Factors Affecting Per Capita Demand of water:
(a) Size of the city: The per capita demand of larger cities is usually larger than that of smaller cities as larger cities tend to have homes with sewerage.
(b) presence of industries.
(c) Habits of the people and their economic condition.
(d) Climatic conditions.
(e) Water quality: If water is aesthetically medically safe, consumption will increase as people will not resort to private water sources etc.
(f) pressure in the distribution system.
(g) Efficiency of Water Works Administration: Leakage in waterways and services; And unauthorized use of water can be kept to a minimum by survey.
(h) water cost.
(i) Policy of metering and method of charging: Water tax is levied in two different ways: on the basis of meter reading and on the basis of fixed monthly rate.
Fluctuations in the rate of water demand
Average daily water consumption per capita demand
= Quantity required in 12 months/ (365 x population)
If this average water demand is made at all times, it will not be enough to meet the fluctuations.
- Seasonal Variations: Demand is at its peak during the summer. The incidence of fires is usually higher in summer, which increases the demand. So, there is seasonal variation. quantity of water depends on seasons.
- Daily variation: The daily variation depends on the activity. People use more water during holidays and festival days, thus increasing the demand for water these days.
- Hour variations are very important because they have a wide range. The bulk of the daily requirement is taken during the active domestic work hours, ie from 6 to 10 in the morning and from 4 to 8 in the evening. During other hours the requirement is negligible. In addition, if a fire does occur, a large amount of water is required to be supplied during short periods, necessitating a maximum rate of supply per hour.
Therefore, sufficient quantity of water or amount of water should be available to meet the peak demand. To meet all the fluctuations, the supply pipeline, serving reservoir and distribution pipes must be in proper proportion. Water is supplied directly from the pump and the pump and distribution system must be designed to meet peak demand. Monthly variation affects the design of storage reservoirs and hourly variation affects the design of pumps and service reservoirs. As the population decreases, the rate of fluctuation increases.
Maximum Daily Demand of Water
= 1.8 x Average Daily Demand
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 of water
Quantity of water in 1 cubic meter
The quantity of water is 1000 liters in 1 cubic meter.
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