Types of Demand of Water

Before the design of the Water Supply Scheme Daily, Monthly as well as Total yearly usage and fluctuations in this consumption throughout the year have to be determined.  But first of all we need to know what kind of water will be used.  Determining actual water consumption is not entirely possible, but based on certain empirical formulas and experience, different types of water consumption can be shown as follows:

1. Domestic Demand

2. Commercial and Industrial Demand

3. Fire Control Demand Public Loss

 4. Demand at Public Places

5. Other Losses or Wastage.

1) Domestic Demand

Domestic use of water i.e. for drinking, bathing, washing clothes, cleaning of house and toilets etc. as well as water consumption for cooking. 

Generally household consumption of water depends on the following factors:

– Personal habits of people

– Social status of individual

-Local climatic condition

-Customs of the local people

In our country India  135 liter/ day per person is considered essential water .  While in developed countries this ratio is around 350 lit / day / capita.

 The reason behind this difference is the comparatively high water consumption in modern facilities of developed nations such as air-condition equipment’s , air-coolers as well as other equipment’s.

Generally about half (50%) of the total daily amount of water is spent on household consumption.

2) Commercial and Industrial Demand:

Commercial or industrial places include private as well as public entertainment places, hotels, offices, shopping centres as well as manufacturing places like factories and factories etc.  The water supply of the water supply scheme should be designed keeping in view the consumption of about one-third of the total water consumption in this type of consumption.

Such usage depends on the structure of the city and its business development as well as the development of the population and the area.

3) Fire Fighting Demand

Fires usually occur in densely populated areas or in industrial estates or factories.  Fires cause severe damage to property and sometimes even loss of life.  There are many causes of fire such as explosion of electrical short circuit ammunition, fire in flammable substances or chemicals, intentional arson by criminal elements as well as fire as a result of an accidental mistake. 

Fire brigades or fire fighting squads are deployed in every city or municipality for fire fighting.  Therefore, special water mains as well as fire hydrants are installed on the main water lines to control the fire from where the required water is obtained.

Generally 5 to 10 percent of the main water supply is reserved for firefighters.  This quantity for firefighting is calculated using the following empirical formulas:

A)National Board of fire underwriter’s formula

 Q = 4637 P (1 -0.01 VP )

where

 Q = required amount of water in liters/minute

 P = city population in thousands

B)Kuiching Formula: 

Q = 3182 / P

C)Freeman’s Formula:

Q = 1136.51(p/10 +10 )

 (D) Buston’s Formula

Q = 5663 / P

Kuchling’s formula corresponds to the position of our country and gives satisfactory results. 

4) Public Demand

 Public use of water in public places such as hospitals, schools, colleges, town halls, places of worship, prisons, inns, etc.  as well as sprinkling of water on public roads, watering of gardens, cleaning of sewers and drains, decoration.  Includes water required for public fountains etc. 

Generally, 7 to 10% of the water supply is allocated for public consumption. 

5) Demand for Other Losses and Wastage:

 The amount of water  distributed from the water supply scheme does not reach 100%  to consumers  

 The main reasons for this are as follows

 (A) Defective pipe joints

(B) Cracks in pipe lines

 (C) Breakage in pipe lines

 (D) Faulty valves and fittings

(F)Loss due to carelessness of consumers

 (E) Water theft due to unauthentic connections

The cost is assumed to be about 15% when calculating the water supply for the above minor reasons.

Computation of Quantity of Water :

 When designing a water supply scheme for any city, that city has to calculate the amount of water required.  For this, first of all, the individual quantity is calculated based on the population of the city.

 This calculated quantity is known as “per capita water demand”.

Per Capita Demand:

Generally the required amount of water per person per day is known as “Per Capita Demand”.

 The following formula is used to calculate this:

 Daily water consumption per person

=Q/ 365 P (liters / man / day)

where

Q = Total water requirement (in liters) throughout the year

P = The population of the city

water consumption rate unit is Ipcd (liter per capita per day). 

Analysis of Rate of Demand for Water Consumption:

 The following figures are obtained from the analysis of general water consumption for small towns in our country:

Considering the approximate figure of the population of any city from this,

The daily water volume of that city

 = 270 x population figure

= 270 x P liters / day (P = Population)

and hence the amount of water required throughout the year

 Q = 270 x 365 x P liters. 

According to Indian Standard Code Is: 1172-1971, any city in our india water required is 135 liters of water per person per day. 

Fluctuation In Demand

 Water consumption is calculated in different ways.  It usually calculates the demand for the whole year based on the average daily consumption. 

 Experience has shown that water consumption rates are not the same throughout the year.  But according to time, day, mass and seasons this consumption varies. 

 The fluctuations of water consumption are classified according to time into three types as follows:

 (i) Hourly fluctuation in demand at different times of the day

 (ii) Daily fluctuation in different days

 (iii) Seasonal fluctuations (water consumption according to different seasons)

(i) Fluctuations in water consumption at different times of the day:

 Observing the daily consumption of water reveals that the consumption is not the same all the time throughout the day. 

From 7.30 am to about 10 am, maximum water is used for bathing, washing clothes and cooking.

Consumption is then very low from 12 noon to 4 pm.  This is followed by a slight increase in re-consumption in the evening and is usually stopped from 11 pm to 4 am.

In this way the fluctuations in water consumption throughout the day can be seen from the graph shown below.

Pick hours are usually 1.5 times more than average consumption.

(ii) Daily Fluctuation:

The rate of water consumption is not always the same i.e. every day.

 It depend on Climate variation, holidays as well as certain festivals or fairs, public celebrations, etc.

During the days of any city or area water consumption is high.  Water consumption is higher on dry days than on rainy days.

 In the same way, people use more water for bathing and washing clothes on Sundays or holidays than on other days.

 In addition, fire as well as whirlwind days consume more water. 

Observations It can be said from above that the consumption of the days with maximum consumption than normal days is assumed to be about 200% i.e. twice.

(iii) Seasonal Fluctuation:

The rate of water consumption varies from season to season and from month to month.

 The summer season uses much more waterfor bathing, drinking, washing clothes and cleaning houses than other seasons.

  In the same way water consumption is very low on very cold days.  Consumption rates vary from season to season.

 As the average daily consumption in normal days is 120 liters which goes up to about 100 to 180 liters in summer season while in winter it drops drastically to 70 to 80 liters. 

Thus the weather and temperature of each season have an effect on water consumption.  Therefore water supply pipelines and mains are designed keeping in view the maximum consumption rate.

Factors Affecting Water Demand

Their are Many  factors affect the rate of water supply or water demand, some of the major factors can be shown as follows

 (1) Climate  Or climatic condition

 (2) Habits and living standard of people

(3) Water supply arrangement

 (4) Sanitation system

 (5) Population of the city

 (6)  Developmental pattern of the town

(7) Metering system

 (8) Pressure in distribution system

 (9) Quality of water

(10) Industrialization 

(11) Cost of water

(1) Climate Condition

In hotter and drier climates, the demand for water for air conditioning as well as bathing and other cleaning is higherthan in colder regions.

 (2) Habits and living standard of people / consumers:

The type of standard of living of the consumer class has a great impact on water consumption.  As resource availability increases, water consumption increases.

 (3) Water supply arrangement:

Water supply arrangement i.e. if water is supplied at fixed times or at certain intervals during certain days instead of continuous distribution of water for the whole day, water consumption will be done properly and economically depending on the amount of consumption Can be controlled. 

(4) Sanitation system:

 The type of sewerage system of any city or town has a great influence on the demand for water.  As the sanitation system develops, the rate of water consumption for its devices increases. 

(5) Population of the City / Town:

Generally small towns have low water consumption rate.  While in big cities the rate of water consumption is high due to the development of sanitation system and industries.  The rate of population directly affects the rate of water consumption. 

(6)Developmental pattern of the town

 Water consumption also depends on how the city is located.  Different patterns of city habitation affect its pipeline system.  The water-distribution system of a city inhabited with a tangled pattern also has a lot of confusion and expense.  Consumption is controlled in low-cost cities due to lower costs. 

(7) Metering system:

Water charge is determined by the water supply department in each city.  In cities where water consumption charges are levied at a flat rate, the rate is higher by both the people and the distribution system.

 But if the meter system is adopted for this charge, the unnecessary expenditure of water by the citizens is very less.  In addition, leaking water can also be controlled.

 (8)Pressure in distribution system:

The pressure of water distribution system has a direct effect on water consumption.  As the pressure increases, the rate of distribution increases and so does the consumption. 

(9)Quality of Water:

 If the water supplied to the people is of high quality then the interest of the people towards it increases and its consumption also increases.  If water quality is poor, people are reluctant to consume it and it reduces overall consumption.

(10) Industrialization :

 In cities where industrial development is high, the demand for water also increases due to industrial purpose and as a result water consumption also increases. 

(11) Cost of water:

The cost of water has a direct effect on its consumers.  This means that as water becomes more expensive, its consumption decreases.  Conversely, where the cost of obtaining water is lower, its consumption increases.

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We all know that water or fluid are supplied from one location to the another location using pipeline networks.So we will see in detail how pipeline construction is carried out.

After designing the pipelines required to supply water to the public for various purposes, the process of pipeline construction for water distribution is known as “Laying of pipe lines”.

 Pipelines are usually laid underground  But it can also be laid on the ground when the pipeline passing through an open area is not obstructing anyone and there is no possibility of any damage to the pipeline. 

Procedure for laying of pipes :

pipeline construction is done in the following different stages:

1) Preparation of Detailed map

2) Setting out the center line Excavation of trenches

3) Laying and connecting pipes

4) Lowering and jointing of pipes

5) Testing for leakage and pressure

6) Back filling & cleaning of site

7)Testing of pipeline

1) Preparation of detailed map:

After conducting an engineering survey of the pipeline, as per its detailed proposal, a map showing the space or area through which the pipeline is to pass may be prepared along the roads, streets and lanes etc. 

The proposed pipeline is shown on this map along with its size (length, diameter, etc.).  In addition to this, other details like existing pipelines, sewer lines and telephone lines in the area are also shown on this map.  In addition to these details, things like valves, stand posts applicable to the proposed pipeline are also marked so that the work can be done easily without any difficulty when the execution of the pipeline is carried out.

2) Setting out the center line: 

After preparing a detailed map for the pipeline plan, the center line of the pipeline is printed on the actual locations.  Pegs or stakes are placed every 30 meters to mark the center line.  This distance is kept from 5 m to 15 m in the diagram of the pipeline where curvatures occur.  Where roads or streets have curbs, the centre line of the pipe is measured from the curb.

Site Cleaning

Making Center Line of Pipe

 3) Excavation of trenches:

After the center line of the pipeline is marked on the ground, digging of trenches is started.  The width of the trench is usually 30 cm to 45 cm or more than the diameter of the pipe.  The width of the trench is about 15 to 30 cm more than pipe diameter where joints are comes.

The trench is dug in such a way that the both ends of  pipe hang freely while the rest of the pipe touches the bottom of the trench.

The pipe is usually kept at a depth of about 90 cm below the ground level so that the pipes do not break due to heavy traffic above it. 

Timbering to the trench should be provided on both sides of the trench if the pipe is to be dug deep in soft or slippery soil. 

4) Lowering and jointing of pipes:

After the excavation of the trench is completed, the laying of pipes is started.  There are usually two things to keep in mind when laying pipes and connecting them.  On the one hand, the pipes are placed on the opposite side of the trench to make the work easier. 

And work is started from its lower level.  In which the pipes should be connected in such a way that the socketed end of the pipe is facing towards the higher side.  As well as aligning the pipe, jointing is also done.

 5) Testing for leakage and pressure:

 Pipes are tested in a standardized manner for leakage and pressure after they are lowered and aligned.

6) Back filling and site cleaning:

After proper testing of pipes is completed, backfilling is done by the soil removed during excavation.  When filling the trench, the soil is carefully filled by pressing the soil on the rotating side of the pipe, after filling the trench, the surplus soil is removed and the site is cleaned.

Specification for laying of pipes

 (1) Unloading of Pipes:

Two men should be used for unloading pipes weighing up to 60 kg when mechanical equipment is unavailable for unloading pipes from transport equipment.

 Heavy pipes from trucks or wagons should be tied with ropes and then slides off the planks with a slope of no more than 45. 

 Only one pipe should be lowered at a time. Under no circumstances should the pipe be thrown down from the carrier and should not be pulled or rolled in such a way as to rub against a hard surface.

(2) Storage of pipes:

Handling and storage should be done very carefully to prevent damage to pipes and their fittings.

 The pipes should be arranged in a row on one side of the trench parallel to the midline of the trench.  The socketed ends of the pipes held in this way should be kept towards the upstream side of the flow. 

Pipes of the same type and diameter should be stacked.

(3) Cutting of the pipe:

When a pipe is to be cut to a certain length, a line should be drawn with a chalk on the side of the pipe at the place where it is to be cut. 

This line should be marked in such a way that it is perpendicular to the mid line of the pipe. 

The pipe should be held firmly on two parallel wooden rafters nailed with cross beams in such a way that the marking of the part to be cut is between these two beams.

The pipe should be cut very precisely from the spot marked with the help of a carpenter’s saw or a long bladed hex.

 Cutting the pipe should be avoided as long as possible by keeping the end part hanging, as the weight of this hanging end is likely to cause the pipe to be cut before it is fully cut.

 (4) Excavation of trenches:

Excavation of trenches should be done in such a way that the pipe stays in its fixed alignment and at a certain depth.

 If the soil at the bottom of the trench is soft or has a made up bottom, the soil should be well soaked and rammed and if there are any depressions in the bottom of the trench, it should be filled in layers with a thickness of 20 cm with sand.

When the bottom of the trench is extremely hard or rocky or gravelly, the trench should be excavated at least 15 cm below its designed grade, followed by stone, gravel or sand. 

 The trench should be filled to its required grade (Fine moorum can be used instead if fine soil or sand is not available nearby).

 A flat surface should be prepared by compacting the clay thus filled.  If blasting is required to dig a trench in any case, it should be removed to a safe place if there are pipes or other damaged material around the blasting site as well as already covered pipeline near the site to prevent damage to such material due to blasting.

After digging the trench, instead of inserting sockets in the pipe, cavities are prepared.  This excavation is done in such a way that there is enough space at the bottom of the pipe to connect the pipe joints and the rest of the pipe can be adjacent to the bottom of the trench. 

Once the pipe is connected, these socket holes or hollows should be filled with sand.  Necessary timbering work should be done during excavation and if water enters the trench, the trench should be dug by proper dewatering.

(5) Laying of pipes:

Pully block, shear legs, chains are suitable for laying pipes in the trench.  Ropes as well as other erection equipments should be used.  Never push the pipe into the ditch by rolling or dropping. 

One end of each rope should be tied to an iron or wooden peg dug into the ground and the other end should be held in a man’s hand and the pipe should be lowered slowly.

 The trench pipes should be arranged in such a way that the spigot of one pipe is exactly centered in the socket of the other pipe and then it should be pushed carefully and fitted to the full depth. 

Pipeline should be laid with proper connection of pipes and at proper level.  Each pipe should be fairly flat so that it touches the bottom of the trench.

Soils with a texture similar to black cotton soil, when saturated or dry, tend to soften or crack, respectively.

An sand layer of at least 10 cm thickness should be made on the rotating side of the pipe in the trench of pipes passing through such clay area.

 Formation of thrust blocks to protect the structure of the pipe against hydraulic thrust in front of each section where the direction or size of the pipeline changes or where the dead ends occur. 

(6) Backfilling of trenches:

Backfilling must be required to prevent damage from falling stones in the trench or movement in the position of the pipe in the open trench.

 In addition to this, in case of flood or discharge of water in the open trench, the work of filling the trench should be done immediately to avoid the possibility of lifting the pipeline. 

The soil around the pipe as well as the bottom should be packed by crushing and grooving so that the pipeline has a uniform and continuous support.

 The tamping bar should be used for tamping the soil and water should be used to fill the trench soil evenly.

The clay used in filling the trench should not initially contain lumps or stones.  When filling the soil, it should be filled with proper consolidation in layers about 10 cm thick without filling it all at once and the soil should be pounded till a cushion of about 30 cm is formed on the pipe.

 Normally after the entire trench is filled, about 10 cm more soil should be raised from the surface of the trench and it should be compacted properly.  By doing so the soil inside the trench becomes natural.  Excess clay from the top is properly incorporated into the trench.

(7) Hydrostatic Test:

 After construction of any new pipeline, its proper connection and after completion of trench refilling, the following tests are performed:

(i) Double the working pressure at which the pipe water is to be carried or  The pipe is tested by applying high pressure. 

Each joint must prove to be completely hydrated during the effect of this pressure.

(ii) After completion of pressure test, leakage test is done for a period of at least two hours with the pressure as prescribed by the local authority.

 Hydrostatic testing of each section of about 500 m length is usually done during the ongoing work of the pipeline.  By doing this test, if there is any error in the workmanship during the ongoing work, rectification can be done immediately at low cost. 

(8) Leakage test:

Water is filled in the section to be tested to find out how much water is leaking from the newly laid pipeline.  And care is taken that no air remains anywhere in the entire section.  After observation for about two hours, water leakage is calculated using the following formula:

Q=ND √P/3.3

Where,

 Q = Allowable leakage Cm³ / hr

N = Number of joints in the section

 P = Average test pressure kg / cm²

 D =  Dia. Of pipe in mm

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3)ADVANTAGES

4)DISADVANTAGES

5)METHODS

6)COMPONENTS

7)MODELS

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