1. Water Distribution Systems, Types & Methods
Dr. Prabha Joshi, Asst. Professor
Department: B.E. Civil Engineering
Subject: Environmental Engineering - I
Semester: VI
Teaching Aids Service by KRRC Information Section

2. Remember the Water Cycle…

3. Where is the Water? 97% water is salt water in oceans
3% is fresh water
67% of this is snow & ice
only 1% of global water is accessible
98% of accessible water is groundwater
2% of accessible water is surface water
Humid climates: 40% of PPT  groundwater
Mediterranean: 10-20%  groundwater
Arid/semi-arid: <1%  groundwater

4. Background
Groundwater: Water that occurs in saturated zones beneath the soil surface.
the water that lies beneath the ground surface, filling the pore space between grains in bodies of sediment and clastic sedimentary rock, and filling cracks and crevices in all types of rock.
source of ground water is rain and snow that falls to the ground a portion of which percolates down into the ground to become ground water

5. The Basics
Infiltration: downward movement of water into soil under the influence of gravity.
Percolation: movement of water in the saturated zone under the influence of hydrostatic head.

6. Sources of Groundwater
Meteoric water: it is the water derived from precipitation.
Connate water: this is the water preset in the rock right from the time of their deposition in an aqueous environment. It is commonly saline in nature.
Juvenile Water: It is also called magmatic water, It is the water formed in crevices or cracks or pores of rocks by condensation of the steam emanating from hot molten masses. It is of only theoretical importance.

7. Understanding the system
Zone of aeration: Soil surface  water table top
Soil water zone
Soil surface through the root zone
Vadose zone
Soil water zone  capillary fringe
Capillary fringe:
Water from saturated zone is pulled up
Zone of saturation: below the water table

8. The Water Table
Saturated zone: the subsurface zone in which all rock openings are filled with water.
Water table: the upper surface of the zone of saturation.
Vadose zone: a subsurface zone in which rock openings are generally unsaturated and filled partly with air and partly with water; above the saturated zone.
Capillary fringe: a transition zone with higher moisture content at the base of the vadose zone just above the water table.

9. The Water Table

10. The Movement of Ground Water
most ground water moves relatively slowly through rock underground
because it moves in response to differences in water pressure and elevation, water within the upper part of the saturated zone tends to move downward following the slope of the water table.
Movement of ground water beneath a sloping water table in uniformly permeable
rock. Near the surface the ground water tends to flow parallel to the sloping water table

11. Discussion Can the zone of aeration be saturated?
Yes, but only temporarily
Is the water table static (does it move)?
Yes, in response to ppt, management
What are effluent streams?
Perennial; grazing streams; fed by groundwater
What are influent streams?
Losing streams; stream  groundwater

12. Perennial Stream (effluent) (from Keller, 2000, Figure 10.5a)
Water table is higher than the water level in the stream.
Humid climate
Flows all year -- fed by groundwater base flow (1)
Discharges groundwater
S. Hughes, 2003

13. Ephemeral Stream (influent) (from Keller, 2000, Figure 10.5b)
Water table is lower than the water level in the stream.
Semiarid or arid climate
Flows only during wet periods (flashy runoff)
Recharges groundwater
S. Hughes, 2003

14. Groundwater Movement POROSITY = F or n (units - fraction or %)
= fraction of void space (empty space) in soil or rock.
Represents the path water molecules can follow in the subsurface
Primary porosity - intergranular
Secondary porosity - fractures, faults, cavities, etc.
Porosity = volume of pore space relative to the total volume (rock and/or sediment + pore space). Primary porosity (% pore space) is the initial void space present (intergranular) when the rock formed. Secondary porosity (% added by openings) develops later. It is the result of fracturing, faulting, or dissolution. Grain shape and cementation also affect porosity.
S. Hughes, 2003

15. High Low Permeability and Hydraulic Conductivity WELL SORTED
Fine (silt-clay)
WELL SORTED
Coarse (sand-gravel)
POORLY SORTED
Coarse - Fine
Permeability and Hydraulic Conductivity
High
Low
Sorting of material affects groundwater movement. Poorly sorted (well graded) material is less porous than well-sorted material.
S. Hughes, 2003

17.                                                                    
Permeability:
The rate at which water or other liquids passes through the pore spaces of a rock.

18. Porosity: total void space in rock or soil as volume
10% for glacial till
20-50% for sands and gravels
33-60% for clays
Effective porosity: ratio of void space through which water can flow to the total volume
Permeability: Degree of connectedness of the pores

19. Groundwater Movement
PERMEABILITY is the capability of a rock to allow the passage of fluids. Permeability is dependent on the size of pore spaces and to what degree the pore spaces are connected. Grain shape, grain packing, and cementation affect permeability.
SPECIFIC YIELD (Sy) The quantity of water that a unit volume of aquifer
drains by gravity.
is the ratio of the volume of water drained from a rock (due to gravity) to the total rock volume. Grain size has a definite effect on specific yield. Smaller grains have larger surface area/volume ratio, which means more surface tension. Fine-grained sediment will have a lower Sy than coarse-grained sediment.

20. SPECIFIC RETENTION (Sr) is the ratio of the volume of water a rock can retain (in spite of gravity) to the total volume of rock.
Specific yield plus specific retention equals porosity (often designated with the Greek letter phi):

21. Water Bearing Qualities of Rocks
Aquifer: water-bearing porous soil or rock strata that yield significant water to wells or through which water can move easily.
good aquifers include sandstone, conglomerate, well-jointed limestone, bodies of sand and gravel, and some fragmental or fractured volcanic rocks such as columnar basalt

22. Aquiclude: any water-bearing soil or rock that may be porous enough to hold good quantity of water but being effectively impermeable they do not allow and easy or quick flow through it.
Example: shale, slate, clays
Aquifuge: It is absolutely an impermeable formation through which there is no possibility of storage or movement of water. water-bearing soil or rock that retards flow of groundwater.
Example: compact interlocking granites, quartzites, silts, mudstones
Aquitard: It s a less common term used for an aquifuge or aquitclude that has become locally leaky due to development of joints or cracks

23. Groundwater: aquifers
What would be the properties (porosity/permeability) of conglomerate?
High porosity, high permeability

24. Groundwater: aquifers
What would be the properties (porosity/permeability) of unfractured granite?
Low porosity, low permeability

25. Summary of Groundwater Systems
NOTE: Study each term, and the associated concepts and geologic processes.
(from Keller, 2000, Figure 10.9)
S. Hughes, 2003

26. Water Supply System
Some civil engineers are responsible for designing systems that provide a reliable and clean water supply.
A water supply system begins at a water source.
Water is transported to a treatment facility where the water is treated to ensure the supply is safe.
Once treated, the water is transported to a storage facility (for example, a water tower) where it is stored for future demand.
When a water faucet is opened or a fire sprinkler is activated, water is transported through the distribution system to the consumer.

27. Water Distribution System
Water mains deliver water from treatment facilities to the end user. This work is accomplished through a well planned distribution system. A distribution system for supply of water includes-
Distribution or service reservoirs for storing treated water, stabilizing pressures and feeding into the distribution pipes.
Pipe lines of various sizes which includes main, submains, branches and laterals for carrying water.
Valves for controlling flow of water in pipes.
Control valves: located throughout the system to shut down sections.
Shut- off Valves: Used to shut off water flow to individual customers and hydrants.

28. Fire Hydrants 4. Hydrants to provide water for fire-fighting purposes.
Installed on both public and private water systems.
Consists of an upright steel casting attached to the underground distribution system.
5. Pumps for supplying water to the service reservoir or distribution pipes.
6. Meters for measuring quantity of water supplied.
Water distribution usually accounts for 40-70% of the total outlay of the water supply system.

29. Fire Hydrant

30. Definition
Head
Relates energy in an incompressible fluid (like water) to the height of an equivalent column of that fluid
In fluid dynamics, head can be measured by the height to which water rises in a column when directly open to the water.

31. Definition Static Head Potential energy of the water at rest
Measured in feet of water
Change in elevation between source and discharge
Ex: What is the static head at a residential supply line if the water level in the elevated tank is 943 ft and the elevation at the supply line is 890 ft?
943 ft – 890 ft = 53 feet of water
[After animating the example, ask students to calculate the static head before clicking to show the calculation.]
EPA at

32. Definitions
Head Loss
Energy loss due to friction as water moves through the distribution system
Pipes
Fittings
Elbows, tees, reducers, etc.
Equipment (pumps, etc.)
Major losses = head loss associated with friction per length of pipe
Minor losses = head loss associated with bends, fittings, valves, etc.

33. Water Distribution System
Consists of water lines, fittings, valves, service lines, meters, and fire hydrants
Loop system more desirable than branch system
Isolation valves
Water flows in more than one direction
LOOP SYSTEM
BRANCH
SYSTEM
The water distribution system includes all of the water lines and components attached to the water lines.
There are basically two different distribution system configurations: Loop systems and branch systems.
Loop systems are more desirable because they provide redundancy. If a leak occurs in a loop system, installed isolation valves can be used to close off a small area near the leak but allow the remainder of the system to continue to provide water. In a branch system, the entire system must be shut down to repair a leak.
In addition, the loop system allows water to flow from more than one direction which can reduce the negative effect felt in a branch system when upstream demand reduces pressure and flow rate.

39. In the dead end system (also called tree system),one main pipeline runs through the centre of the populated area and sub-mains branch off from both sides. The sub-mains divide into several branch lines from which service connections are provided.

41. Advantages
The distribution network can be solved easily and it is possible to easily and accurately calculate the discharges and pressures at different points in the system.
Lesser number of cut-off valves (i.e. sluice valves) are required in this system.
Shorter pipe length are needed and the laying of pipes is easier.
It is cheap and simple and can be extended or expanded easily.

42. Disadvantages
Water can reach a particular point only through one route, any damage or repair in any pipe line will completely stop the water supply in the area being fed by that water pipe.
There are many dead ends in the system which prevent the free circulation of water and may lead to degradation in its quality.
The stale water should therefore be removed periodically at dead ends by providing scour valves. This will result in greater wastage of treated water and will necessitate careful attendance at each valve.
Since the discharge is reaching a point from only one direction the supplies during firefighting can not be increased by diverting any other supplies from any other side.

43. Scour Valve

46. Gridiron Distribution System
Description:
In this system the main supply line runs through the centre of the area and sub mains branch off in perpendicular directions.
The branch lines interconnect the sub-mains. This system is ideal for cities laid out on a rectangular plan resembling a gridiron.
The distinguishing feature of this system is that all of the pipes are interconnected and there are no dead ends.
Water can reach a given point of withdrawal from several directions, which permits more flexible operation, particularly when repairs are required.

47. Advantages
Since the water reaches at different places through more than one route, the discharge to be carried out by each pipe, the friction loss and the size of the pipe, therefore get reduced.
In case of repairs only a small area will be devoid of complete supply, as at least some supply will be reaching at the point from some other route.
Because of different interconnections the dead ends are completely eliminated, and therefore water remains in continuous circulation and hence not liable to pollution due to stagnation.
During fire, more water can be diverted towards the affected point from various directions by closing and manipulating the various cut-off valves.

48. Disadvantages
This system requires more length of pipelines, and a larger number of sluice valves.
Its construction is costlier.
The design is difficult and costlier, the calculation for determining accurately the sizes of the pipes and the pressures at various key points, is a real tedious job, and may require the services of design experts and even computers.

49. The supply main is laid all along the peripheral roads and sub mains branch out from the main.
This system also follows the grid-iron system with the flow pattern similar in character to that of dead-end system.
So determination of the size of pipes is easy.

50. Ring system
The Ring system is very suitable for towns and cities having well planned roads. Sometimes this system is used as “looped feeder” placed centrally around a high demand area along with the Grid-iron system.
This system is also sometimes called Circular System, in this system a closed ring either rectangular or circular of the main pipes is formed around the area to be served.
The distribution area is divided into rectangular or circular blocks and the main water pipes are laid on the periphery of these blocks.

52. If a city or town is having a system of radial roads emerging from different centers, the pipelines can be best laid in a radial system by placing the distribution reservoirs at these centers.

53. In this system water is therefore, taken from the water mains and pumped into the distribution reservoirs placed at different centers.
The water is then supplied through radially laid distribution pipes.
The calculations for design of sizes are also simple.
Advantages and disadvantages of this system are same as that of the Grid-iron system.

59. Pompeii
Pompeii was an ancient Roman town-city near modern Naples, in the Campania region of Italy, in the territory of the comune of Pompeii. Pompeii, along with Herculaneum and many villas in the surrounding area, was mostly destroyed and buried under 4 to 6 m (13 to 20 ft) of volcanic ash and pumice in the eruption of Mount Vesuvius in 79 AD.
The famous eruption of 79 CE buried Roman cities in a time capsule

60. Mediterranean Volcanoes

61. Water Distribution system of Rome
Water flowed to the city by the force of gravity alone and usually went through a series of distribution tanks within the city.
Generally water was not stored, and the excess was used to flush out sewers. Rome's famous fountains were also supplied in this way.

66. Once in or near Rome, water from the aqueducts passed into large, covered catch-basins. Here waters were supposed to deposit their sediment. Waters from the catch-basins were distributed through free-flowing canals, lead pipes, and terra-cotta pipes to storage reservoirs and then through lead pipes (called fistulae) to users.

68. STREETS IN POMPEII
The streets were angled so that water flowed into the drains.
They were also equipped with stepping stones so that people did not have to walk in the water and filth that was on the streets.

70. PIPES
Because of the series on natural disasters Pompeii had, their water system was not as extensive as when the city was at its height.
However, several lead pipes have been found still in position.
Also, water storing stations that were still operational when Mt Vesuvius erupted have been found.

73. Vesuvius and Monte Somma

74. Street Scene in Pompeii

75. Roman Fast Food

76. Roman Plumbing

77. Victim of Vesuvius

78. Victims of Vesuvius

92. Gravitational System
In this system the water from the high levelled source is distributed to the consumer at lower levels by the mere action of gravity without any pumping.
For proper functioning of the system the difference of the head available between the source and the localities must be sufficient enough as to maintain adequate pressure at the consumer’s door step after allowing frictional and other losses in the pipes.
** greater is the head loss lesser dia is required to pass a given discharge.

93. This system is designed so as to leave only the minimum permitted available head to the consumers. This will keep the leakages and the wastages to the minimum and will also reduce the required sizes of the pipes.
In Mumbai the water which is brought from the high lakes situated in the hills is distributed to the consumers by this method.

94. Pumping System

95. Treated water is directly pumped in to the Distribution main without storing.
Also called pumping without storage system.
High lift pumps are required.
It requires constant attendance as the pumps are to be kept in working condition all the time and sudden failure of the pumps would lead to great hardship.
If power supply fails there will be complete stoppage of water supply. The method is not generally used.
The only advantage of this method is that during fire it can force large volumes of water under high pressure in the required direction.

96. Combined Gravity and Pumping system

97. Combined Gravity and Pumping system

100. Advantages
This system is adopted in most of the cases as it has following advantages.
In case of fire, pumps can be used to develop high pressure, or a fire demand can be directly satisfied from the pump house by closing the inlet valve for the elevated reservoir.
In this system since the pumps work at usually uniform rate, they suffer less wear and tear.
This system of distribution is economical.
The system is fairly reliable in the sense that some quantity of water is available from the elevated reservoir even during breakdown of pumps.

105. The coefficient of lateral earth pressure, K, is defined as the ratio of the horizontal effective stress, σ'h, to the vertical effective stress, σ'v.

108. This garden is known to be constructed in 1881 over a main reservoir
This garden is known to be constructed in 1881 over a main reservoir. The primary purpose of which was to secure the water from the nearby activities. This stone placard reads this “The reservoirs beneath this garden were constructed in 1880 and extended to hold 90 million gallons in 1921.
This garden is known to be constructed in 1881 over a main reservoir. The primary purpose of which was to secure the water from the nearby activities. The reservoirs beneath this garden were constructed in 1880 and extended to hold 90 million gallons in 1921.