b) Rainwater harvesting: Introduction to rainwater

a) Water distribution system: System of water supply- Continuous and intermittent system. Different distribution systems and their components. ESR- Design of ESR capacity. Wastage of Water- Detection and Prevention. b) Rainwater harvesting: Introduction to rainwater harvesting, need of rain water, methods of rainwater harvesting, components of domestic rain water harvesting system, design of roof top rainwater harvesting system. c) Introduction to Packaged WTP in townships, big commercial plants, necessity (On-site water treatment). Introduction to process description of RO, Pressure Filters

* Water Distribution System

Purpose: To convey water from WTP to the individual consumer, in sufficient quantity and with adequate pressure

Basic requirements: Functional: Configuration of pipes Location & type of valves,

Hydraulic: Adequate residual pressure even at peak hours

Methods of distribution: governing factors? Topography: key factor; if favourable topography – gravity supply possible through tunnels / pipelines else pumping or pumping + gravity flow required

Water Distribution System

Continuous Supply

24 hrs water supply :possible when water in sufficient quantity available

Losses? May be

Intermittent water supply

Most of cities have this kind of supply

Storage @ consumer end required

Chances of contamination during Non Supply Hrs (NSH)

Special efforts required to restore supply during NSH Large no of valves required to be operated (start / shut of supply; to cutoff a particular area)

Flow of water merely by gravity

Water may be supplied to different reservoirs within the city by gravity. System is economical as no pumping is required

Mumbai – treated water from Pise Panjarapur --pumped (40 m) --- supplied to all reservoirs by gravity

* Gravity Supply

Uses mechanical – electrical energy Water is supplied to consumers and / or reservoirs under pressure Raw water mains --- Bengaluru Distribution mains --- Ahmedabad (few years back)

Combined gravity & pumped system • Storage reservoirs: used to maintain adequate pressure (elevation); filled during non-peak hours --- water supplied through them along with regular pumped water supply during peak demand

* Pumped Water Supply

Basis of classification:

* Water Supply Systems

Based on hrs of supply Based on type of flow

Continuous Gravity – Parvati WTP to old parts of Pune city

Intermittent Pumping: olden days – Ahmedabad

Combination (p + g) ; Water pumped to ESR during n p hrs

• Distribution network: Series of interconnected pipes distribution network (DN)

• Various networks possible • Network to be adopted depends on place, orientation of roads, local conditions

• Various possible types include 1. Dead end system

2. Grid iron system

3. Ring system

4. Radial system

* Water Distribution Networks

* Dead End System / Tree System / Branching System

Structure – similar to tree Trunk / main line: main source of Water Supply

service mains / sub-mains – connected to mains

Branches – connected to sub mains

Network adopted for older towns that have developed in haphazard manner, without proper planned roads (almost all cities and towns in India, except a few)

Advantages: Easy to analyze and calculations are more accurate

Less no of sluice valves are required to be provided

Pipe lengths are short & hence laying is easy

Cheap, simple and easy extension possible

* Dead End System

Bacterial growth possible at dead ends. scour valves must at dead ends

During maintenance all D /S consumers suffer as water reach to them through the same pipe During fires flow diversion is not possible and

therefore can be troublesome

Due to extensions, pressure drop may occur and its difficult to restore as no connectivity. Only solution is lay parallel pipes / mains / sub mains which is costlier

* Disadvantages of Dead End System

* Grid Iron System

Most convenient for towns with proper road networks

e.g. Chandigarh Each point gets water ( or major part of the city) from more than 1 points, hence very useful during emergencies

No dead ends no stagnation of water reduced chances of bacterial contamination / otherwise Disadvantage / challenge?

* Grid Iron System

Advantages:

• Each point gets water ( or major part of the city) from more than 1 points

• In case of repairs, very small area devoid of complete supply, as at least, some supply will be reaching at the point from other route

• Continuous circulation of water, hence not liable to pollution

• During fire more water can be diverted towards affected point

Disadvantages:

• The length of pipe required is more and number of sluice valve also increases.

• Its construction is costly

• The design calculations are difficult. Determination of size of pipes and pressure at key points is tedious job.

* Circular / Ring System

Circular / Ring System

• A closed ring, either circular or rectangular, of the main pipe is formed around the area to be served.

• This system is suitable for well planned towns and cities

• For higher demand areas the ring system is used with grid iron system

* Radial System

Radial System

All above systems are helpful during emergencies

No dead ends no stagnation of water reduced chances of bacterial contamination / otherwise; No of valves to be operated are more

Head loss (valves; pipes’ friction; bents; meters) etc.

“Effective head available” imp. Factor for “design”

Normally in design: 7 m residual pressure. Considered @ consumer end for single storied; 12 m -2 s, 17 m – 3 s

Distribution reservoirs Balancing reservoirs: quantity for balancing variations in

demand & supply, buffers, mass curve to be used

Break down: pumps may fail / power failure; main source of w s may get damaged

Fire reservoirs: quantity to be kept reserved for fire fighting --- fire demand formulae Fire reserve = (f – c) t --- f = fire demand; c = fire pumping

capacity; t = duration of fire;

* Pressure In Distribution System

Reservoirs that store treated water for supplying water during emergencies (fire, power failure, repairs)

To cater for fluctuations in hourly demand as well as to maintain adequate pressure Types: Based on material: steel / RCC / masonry

Location : surface / elevated

Surface reservoirs either circular or rectangular constructed at G L or below G L; generally constructed @ highest pt in the city --- Malabar Hills in Mumbai If city area is undulating: more than one reservoirs are provided & zoning pattern is followed;

From G S R: water is sent to d/s in case of gravity flow

* Distribution Reservoir / Service Reservoir

Shape: rectangular / circular / oval

Constructed above g l @ some ht & is supported on supporting structure suitable for areas where combined gravity + pumped supply is made

Material: R C C , Steel Different sizes & shapes are possible (especially in RCC); also its cheap & requires less maintenance. hence RCC ESR are more common these days

Intz type, egg shaped, spherical / bulb, semi – spherical etc.

Stand pipe

* E S Rs (ELEVATED STORAGE RESERVOIRS)

* Stand Pipe

• Either G S R / E S Rs without Support Structure • Height 15 to 30 m,dia.-10 to 15 m • Were common in older days

* Determining Storage Capacity Of A Reservoir

Total storage capacity = ς (balancing storage + breakdown storage + fire storage)

Balancing storage: main function of distribution reservoir: to satisfy fluctuations in demand by acting as a buffer thereby ensuring constant supply Quantity required to be stored in the reservoir for equalizing variable demand balancing storage / balancing reserve / storage capacity of a balancing reservoir

Breakdown storage: emergency repairs / power failures Fire storage: uncertain, general consideration @

01 lpcd is 9668: 1980

* Methods to Determine Storage Capacity of A Reservoir

Mass curve method (diagram on board) A mass diagram: plot of accumulated inflow (i.e. Supply)

or outflow (i.e. Demand) v/s time. The mass curve of supply (i.e. Supply line) is, therefore, first drawn and is superimposed by the demand curve. The procedure to construct such diagram is as follows: From the past records, determine the hourly demand for all

24 hours for typical days (maximum, average and minimum). Calculate and plot the cumulative demand against time, and

thus plot the mass curve of demand. Read the storage required as “the sum of the two maximum

ordinates between demand and supply line as shown in fig.” Repeat the procedure for all the typical days (maximum,

average and minimum), and determine the maximum storage required for the worst day.

Hydrographs – refer your hydrology & irrigation (~ for water) Analytical method --- thr’ numericals

b) Rainwater harvesting: Introduction to rainwater harvesting, need of rain water, methods of rainwater harvesting, components of domestic rain water harvesting system, design of roof top rainwater harvesting system.

Necessity of Rain Water Harvesting

1) In areas where there is inadequate groundwater supply, rainwater harvesting offers an ideal solution.

2) It helps in utilizing the primary source of water and prevents the runoff from going into sewer or storm drains.

3) It reduces urban flooding.

4) Recharging water into the aquifers help in improving the quality of existing groundwater through dilution.

Harvesting System

Broadly rainwater can be harvested for two purposes

1)Storing rainwater for ready use in containers above or below ground

Harvesting System

2)Charged into the soil for withdrawal later (groundwater recharging)

Where to harvest rain

Rooftops

Paved & unpaved areas

Water bodies

Storm water drains

Whether to store rainwater or use it for recharge

Rain Water Harvesting

a) Individual House Rain Water Harvesting

Recharge Trench with Bore Method

Borewell with Settlement tank

Open well method with filter bed

Bore well with settling tank

b) Group Houses

ROOF TOP RAIN WATER HARVESTING

Component Parts

1) Catchment

2) Coarse Mesh

3) Gutters

Steel

Wood

Plastic Gutter

Aluminium Gutter

4) Down Pipe and First Flush Pipe

5) Filter Units

Charcoal Filter

Sand Filter

Dewas Filter

Rainwater Harvesting1

Rainwater Harvesting2

c) Introduction to Packaged WTP in townships, big commercial plants,

necessity (On-site water treatment)

Introduction to process description of RO, Pressure Filters

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