What Is Roof Top Rain Water Harvesting?

What Is Roof Top Rain Water Harvesting
Rooftop Rain Water Harvesting is the technique through which rain water is captured from the roof catchments and stored in reservoirs. Harvested rain water can be stored in sub-surface ground water reservoir by adopting artificial recharge techniques to meet the household needs through storage in tanks.

Where is rooftop rainwater harvesting practiced?

Rooftop rainwater harvesting is the most common practice in Shillong, Meghalaya. It is interesting because Cherapunjee and Mawsynram situated at a distance of 55 km. from Shillong receive the highest rainfall in the world, yet the state capital Shillong faces acute shortage of water.

What are the two techniques of rooftop rainwater harvesting?

Hint: Two methods of water harvesting in India: (i) The excess water collected through rainfall can be carried to the wells, which further helps to recharge the wells and underground water. (ii) Collection of rainwater on top of the roof and directing dry tanks.

  1. Complete solution: According to experts, traditional knowledge of water conservation is the only sustainable way to combat the dangers of a national water emergency.
  2. India with its rich culture and heritage, water conservation efforts using images, rituals, traditional knowledge for water conservation, cultural practices on water knowledge and cultural images on water, ancient practices and work in a traditional way with metaphors Water warriors may conclude to confirm the value of traditional heritage on knowledge of water.

Traditional methods of water conservation – Role of women: In ancient times, women were considered as gatekeepers of water ecology and were responsible for: – Construction of world heritage sites like step wells, tanks and even ponds such as Queens step-well (Rani ki Vav) in Patan, Gujarat, and Rani and Padam Sagar in Jodhpur, Tank Nagamandala in Karnataka.

  • Cleaning and maintenance of water bodies – Performing dances and songs: – Girja Devi is singing the story of a woman to fetch water.
  • Listening to the stories of Vidyadhari Bai of Varanasi, she practised catching the friction of the rope against the wall of the well in her voice.
  • Sacred aspect: Water bodies can be used for cleaning and maintaining water bodies.

– Like Uttarakhand, it is believed that the water spirit (masan) is present in all irrigation channels and must be melted for the protection of crops. – The pre-monsoon ritual of Rajasthan, called Lassipa, ensures the aggregation, cleaning and desilting of all water bodies by all villagers.

During the breeding festivals of Gangaur and Aak Teej, women come together to clean the lakes and tanks. Note: Rainwater harvesting such as the construction of tanks. The Rajwani system where water circulates through the sand settles on the gypsum layer and is brought into use by a complex capillary system called berry.

Patali Paani which are deep aquifers which are determined by geological formation. Community Ownership is traditional, water management was a community responsibility. Neeruganti in Karnataka was a person who controlled and managed the distribution of water.

What are the advantages of rooftop rainwater harvesting?

Advantages of using rooftop rainwater harvesting Reduces the cost of pumping groundwater. Provides high-quality water that is soft and low in minerals. Improves the quality of groundwater through dilution when recharged to the ground. Reduces soil erosion in urban and rural areas.

How is rooftop rainwater filtered?

A rainwater harvesting system comprises components of various stages – transporting rainwater through pipes or drains, filtration, and storage in tanks for reuse or recharge. The common components of a rainwater harvesting system involved in these stages are illustrated here.1.

Catchments: The catchment of a water harvesting system is the surface which directly receives the rainfall and provides water to the system. It can be a paved area like a terrace or courtyard of a building, or an unpaved area like a lawn or open ground. A roof made of reinforced cement concrete (RCC), galvanised iron or corrugated sheets can also be used for water harvesting.2.

Coarse mesh at the roof to prevent the passage of debris 3. Gutters: Channels all around the edge of a sloping roof to collect and transport rainwater to the storage tank. Gutters can be semi-circular or rectangular and could be made using:

Locally available material such as plain galvanised iron sheet (20 to 22 gauge), folded to required shapes. Semi-circular gutters of PVC material can be readily prepared by cutting those pipes into two equal semi-circular channels. Bamboo or betel trunks cut vertically in half.

The size of the gutter should be according to the flow during the highest intensity rain. It is advisable to make them 10 to 15 per cent oversize. Gutters need to be supported so they do not sag or fall off when loaded with water. The way in which gutters are fixed depends on the construction of the house; it is possible to fix iron or timber brackets into the walls, but for houses having wider eaves, some method of attachment to the rafters is necessary.4.

Diameter Of pipe (mm) Average rate of rainfall in mm/h
50 75 100 125 150 200
50 13.4 8.9 6.6 5.3 4.4 3.3
65 24.1 16.0 12.0 9.6 8.0 6.0
75 40.8 27.0 20.4 16.3 13.6 10.2
100 85.4 57.0 42.7 34.2 28.5 21.3
125 80.5 64.3 53.5 40.0
150 83.6 62.7

5. First-flushing A first flush device is a valve that ensures that runoff from the first spell of rain is flushed out and does not enter the system. This needs to be done since the first spell of rain carries a relatively larger amount of pollutants from the air and catchment surface.

Source: A water harvesting manual for urban areas

6. Filter The filter is used to remove suspended pollutants from rainwater collected over roof. A filter unit is a chamber filled with filtering media such as fibre, coarse sand and gravel layers to remove debris and dirt from water before it enters the storage tank or recharge structure. Charcoal can be added for additional filtration.

i) Charcoal water filter A simple charcoal filter can be made in a drum or an earthen pot. The filter is made of gravel, sand and charcoal, all of which are easily available. (ii) Sand filters Sand filters have commonly available sand as filter media. In a simple sand filter that can be constructed domestically, the top layer comprises coarse sand followed by a 5-10 mm layer of gravel followed by another 5-25 cm layer of gravel and boulders. (ii. a) Dewas filters Most residents in Dewas, Madhya Pradesh, have wells in their houses. Formerly, all that those wells would do was extract groundwater. But then, the district administration of Dewas initiated a groundwater recharge scheme. The rooftop water was collected and allowed to pass through a filter system called the Dewas fillter, designed by Mohan Rao, district collecter of Dewas, and engineers of the rural engineering services.

The water thus filtered is put into the service tubewell. The filter consists of a polyvinyl chloride (PVC) pipe 140 mm in diameter and 1.2m long. There are three chambers. The first purification chamber has pebbles varying between 2-6 mm, the second chamber has slightly larger pebbles, between 6 and 12 mm and the third chamber has the largest – 12-20 mm pebbles.

There is a mesh at the outflow side through which clean water flows out after passing through the three chambers. The cost of this filter unit is Rs 600. Filter for large rooftops When rainwater is harvested in a large rooftop area, the filtering system should accommodate the excess flow. A system is designed with three concentric circular chambers in which the outer chamber is filled with sand, the middle one with coarse aggregate and the inner-most layer with pebbles. What Is Roof Top Rain Water Harvesting This way the area of filtration is increased for sand, in relation to coarse aggregate and pebbles. Rainwater reaches the centre core and is collected in the sump where it is treated with few tablets of chlorine and is made ready for consumption. This system was designed by R Jeyakumar ( Source: Jeyakumar; Rain water Harvest Manual P-21) Varun: S Vishwanath, a Bangalore water harvesting expert, has developed a rainwater filter “VARUN”. ‘VARUN’ is made from a 90 litre High Density Poly Ethylene (HDPE) drum. The lid is turned over and holes are puched in it. This is the first sieve which keeps out large leaves, twigs etc. Rainwater coming out of the lid sieve then passes through three layers of sponge and a 150 mm thick layer of coarse sand. ii.b. Horizontal roughing filter and slow sand filter The introducton of horizontal roughing filter and slow sand filter (HRF/SSF) to treat surface water has made safe drinking water available in coastal pockets of Orissa. The major components of this filter are described below.1) Filter channel : One square metre in cross-section and eight m in length, laid across the tank embankment, the filter channel consists of three uniform compartments, the first packed with broken bricks, the second with coarse sand, followed by fine sand in the third compartment.

  • The HRF usually consists of filter material like gravel and coarse sand that successively decreases in size from 25 mm to 4 mm.
  • The bulk of solids in the incoming water is separated by this coarse filter media or HRF.
  • At every outlet and inlet point of the channel, fine graded mesh is implanted to prevent entry of finer materials into the sump.
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The length of a channel varies according to the nature of the site selected for the sump.2) Sump: A storage provision to collect filtered water from the tank through the filter channel for storage and collection. While HRF acts as a physical filter and is applied to retain solid matter, SSF is primarily a biological filter, used to kill microbes in the water. For more details: Making Water Everybody’s Business iii. Rain PC AcquaSure, a consortium of three specialist Netherlands-based companies, has developed a system for the conversion of rainwater to drinking water in the form of a Rainwater Purification Centre (RainPC).

  • RainPC is developed by scaling down the multi-staged water treatment method (MST), which involves screening, flocculation sedimentation and filtration and incorporating existing technologies like upward flow fine filtration, absorption and ion exchange.
  • Coming in a small compact 26 kg unit, the RainPC offers an affordable solution by converting rainwater into drinking water.

RainPC is made of ultra violet resistant poly-ethylene housing and cover, stainless steel rods and bolts, a nickel-brass valve and an adapter for maintaining constant volume. Xenotex-A and activated carbon catridges along with ultra membrane filtration or micro-membrane filtration modules incorporated in the RainPC has the capacity to deal with E-coli and the potential of meeting the Dutch as well as World Health Organisations (WHO) water regulation standards.

  • The components can also be transported individually to be assembled at the site.
  • Three product types are available based on their microbial contaminant removal capacity.
  • This technology is ideally suited for virtually any situation and is a blessing particularly for those who have little or no access to regular safe drinking water.

The salient features of Rain PC are: * Simple straight-forward installation * Easy to operate and maintain * Needs no power and operates at low gravity pressure (0.1 bar upward). * The system is capable of providing a constant flow of about 40 liters of rainwater per hour, enough for a family of five for drinking, cooking and bathing purposes.

* Maintains nearly constant volume irrespective of water pressure. * The Xenotex-A and activated carbon cartridge processes up to 20,000 liters and can be regenerated up to 10 times. * Cost per 1000 litres is as low as US$ 2 to 3. (The above information is as per the manufacturers’ claims and not based on any study by CSE.) For further information Email: [email protected] iv.

Rainwater harvester EA Water Pvt Ltd has launched a unique Rainwater Harvester, which filters runoff water from roads, which generally contains oil and grease. This system has been installed in the Gymkhana club, Sector-15, Faridabad, Haryana. Rajit Malohtra, project in charge, of this company explained that the water harvesting system installed at the club has a sand filter, which filters silt from runoff harvested from roof, lawns and parking area. According to Wessels (1994), concerns over the possible negative health effects of rainwater utilisation led to some opposition. The Federal Office of Health, for example, intially objected to its use for washing clothes, personal hygiene and even for toilet flushing, due to possible risks of infection and allergic reactions.

Long-term investigations by the health offices in Hamburg and Bremen, however, have yielded positive results with respect to the use of water for washing purposes and have confirmed that rainwater sources do not present a health risk. (i) Filters developed by WISY Private companies such as WISY, based in Kefenrod in Germany, are playing an important role in promoting rainwater use by developing pumps and filter devices to improve water quality.

WISY has developed a simple filter system, which can be attached to a standard household downpipe. Under conditions in Germany (assuming a mean annual rainfall of 650mm/year), this can divert and filter 90 per cent of the runoff from a roof area of up to 200 square metre. (fig c). A floating fine suction filter for ensuring that the water pumped from the tank is extracted from the cleanest part of the tank and is free of particulates has also been developed. For details contact: WISY (Winkler system) OT Hitzkirchen, Oberdorfstrasse 26, D-63699, Kefendrod-Hitzkirchen Germany; fax:+60-54-912129 [email protected] (Source: John Gould and Erik Nissen-Petersen, 1999: Rainwater Catchment Systems for Domestic Supply – Design, Construction and Implementation, Intermediate Technology Group) (ii) Filters developed by MALLBETON Another company, MALLBETON, a manufacturer of concrete tanks and filters, based in Germany, is marketing a tank design which manages any overflows (Konig, 1998).

This is done by constructing the top half of a sub-surface tank from a porous concrete ring, which allows water to gradually seep into the ground. While this reduces the volume of water available, it does make householders eligible for waivers on their rainwater drainage fees. These fees are already applied to householders and businesses in about 25 per cent of Germany.

The charges that are levied on each square metre of roof area and sealed surroundings can be substantial, such as in Bonn, so waivers often provide significant savings. (Source: John Gould and Erik Nissen-Petersen, 1999: Rainwater Catchment Systems for Domestic Supply – Design, Construction and Implementation, Intermediate Technology Group) Back to Top A storage tank made of galvanised iron sheets 7. Storage facility There are various options available for the construction of these tanks with respect to the shape, size and the material of construction. Shape: Cylindrical, rectangular and square. Material of construction: Reinforced cement concrete, (RCC), ferrocement, masonry, plastic (polyethylene) or metal (galvanised iron) sheets are commonly used.

Position of tank: Depending on space availability these tanks could be constructed above ground, partly underground or fully underground. Some maintenance measures like cleaning and disinfection are required to ensure the quality of water stored in the container.8. Recharge structures Rainwater may be charged into the groundwater aquifers through any suitable structures like dugwells, borewells, recharge trenches and recharge pits.

Various recharge structures are possible – some which promote the percolation of water through soil strata at shallower depth (e.g., recharge trenches, permeable pavements) whereas others conduct water to greater depths from where it joins the groundwater (e.g.

  1. Recharge wells).
  2. At many locations, existing structures like wells, pits and tanks can be modified as recharge structures, eliminating the need to construct any structures afresh.
  3. Here are a few commonly used recharging methods: 1.
  4. Recharging of dugwells and abandoned tubewells.
  5. In alluvial and hard rock areas, there are thousands of wells which have either gone dry or whose water levels have declined considerably.

These can be recharged directly with rooftop run-off. Rainwater that is collected on the rooftop of the building is diverted by drainpipes to a settlement or filtration tank, from which it flows into the recharge well (borewell or dugwell). If a tubewell is used for recharging, then the casing (outer pipe) should preferably be a slotted or perforated pipe so that more surface area is available for the water to percolate.

Developing a borewell would increase its recharging capacity (developing is the process where water or air is forced into the well under pressure to loosen the soil strata surrounding the bore to make it more permeable). If a dugwell is used for recharge, the well lining should have openings (weep-holes) at regular intervals to allow seepage of water through the sides.

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Dugwells should be covered to prevent mosquito breeding and entry of leaves and debris. The bottom of recharge wells should be desilted annually to maintain the intake capacity. Providing the following elements in the system can ensure the quality of water entering the recharge wells: 1. 2. Settlement tank Settlement tanks are used to remove silt and other floating impurities from rainwater. A settlement tank is like an ordinary storage container having provisions for inflow (bringing water from the catchment), outflow (carrying water to the recharge well) and overflow.

  1. A settlement tank can have an unpaved bottom surface to allow standing water to percolate into the soil.
  2. In case of excess rainfall, the rate of recharge, especially of borewells, may not match the rate of rainfall.
  3. In such situations, the desilting chamber holds the excess amount of water till it is soaked up by the recharge structure.

Thus, the settlement chamber acts like a buffer in the system. Any container, (masonry or concrete underground tanks, old unused tanks, pre-fabricated PVC or ferrocement tanks) with adequate capacity of storage can be used as a settlement tank.3. Recharging of service tubewells.

In this case the rooftop runoff is not directly led into the service tubewells, to avoid chances of contamination of groundwater. Instead rainwater is collected in a recharge well, which is a temporary storage tank (located near the service tubewell), with a borehole, which is shallower than the water table.

This borehole has to be provided with a casing pipe to prevent the caving in of soil, if the strata is loose. A filter chamber comprising of sand, gravel and boulders is provided to arrest the impurities.4. Recharge pits A recharge pit is 1.5m to 3m wide and 2m to 3m deep. 5. Soakaways / Percolation pit Percolation pits, one of the easiest and most effective means of harvesting rainwater, are generally not more than 60 x 60 x 60 cm pits, (designed on the basis of expected runoff as described for settlement tanks), filled with pebbles or brick jelly and river sand, covered with perforated concrete slabs wherever necessary.6.Recharge trenches A recharge trench is a continuous trench excavated in the ground and refilled with porous media like pebbles, boulders or broken bricks.

A recharge trench can be 0.5 m to 1 m wide and 1 m to 1.5 m deep. The length of the recharge trench is decided as per the amount of runoff expected. The recharge trench should be periodically cleaned of accumulated debris to maintain the intake capacity. In terms of recharge rates, recharge trenches are relatively less effective since the soil strata at depth of about 1.5 metres is generally less permeable.

For recharging through recharge trenches, fewer precautions have to be taken to maintain the quality of the rainfall runoff. Runoff from both paved and unpaved catchments can be tapped.7.Recharge troughs To collect the runoff from paved or unpaved areas draining out of a compound, recharge troughs are commonly placed at the entrance of a residential/institutional complex.These structures are similar to recharge trenches except for the fact that the excavated portion is not filled with filter materials.

  1. In order to facilitate speedy recharge, boreholes are drilled at regular intervals in this trench.
  2. In design part, there is no need of incorporating the influence of filter materials.
  3. This structure is capable of harvesting only a limited amount of runoff because of the limitation with regard to size.

Book Detail 8. Modified injection well In this method water is not pumped into the aquifer but allowed to percolate through a filter bed, which comprises sand and gravel. A modified injection well is generally a borehole, 500 mm diameter, which is drilled to the desired depth depending upon the geological conditions, preferably 2 to 3 m below the water table in the area.

How many methods of rainwater harvesting are?

There are three main types of rainwater harvesting system: direct pumped, indirect pumped, and indirect gravity.

Is rainwater safe to drink?

Germs and other contaminants are found in rainwater. – While useful for many things, rainwater is not as pure as you might think, so you cannot assume it is safe to drink. Rain can wash different types of contaminants into the water you collect (for example, bird poop on your roof could end up in your water barrel or tank).

  • Rainwater can carry bacteria, parasites, viruses, and chemicals that could make you sick, and it has been linked to disease outbreaks.
  • The risk of getting sick from rainwater may be different depending on your location, how frequently it rains, the season, and how you collect and store the rainwater.

Dust, smoke, and particles from the air can contaminate rainwater before it lands on your roof. Roofing materials, gutters, piping, and storage materials can introduce harmful substances such as asbestos, lead, and copper into the water. Dirt and germs can be washed into collected rainwater from the roof, especially when rain follows several days of dry weather. What Is Roof Top Rain Water Harvesting To lower your risk of getting sick, consider using rainwater only for uses such as watering plants that you don’t eat or washing items that are not used for cooking or eating. Avoid using rainwater for drinking, cooking, brushing your teeth, or rinsing or watering plants that you intend to eat. Instead, use municipal tap water if it is available, or purchase bottled water for these purposes. If you have a weakened immune system, you should be especially careful when choosing your drinking water source. Discuss this with your healthcare provider. Before using collected rainwater for drinking, bathing, or cooking, consider whether treatment is needed to make it safe. Testing the water can determine if there are harmful germs, chemicals, or toxins in it. include filtration, chemical disinfection, or boiling. Filtration can remove some germs and chemicals. Treating water with chlorine or iodine kills some germs but does not remove chemicals or toxins. Boiling the water will kill germs but will not remove chemicals. Using a simple device called a “first flush diverter” to remove the first water that comes into the system may help avoid some of these contaminants. The amount of water that should be removed by a first flush diverter depends on the size of the roof feeding into the collection system. Consider adding a screen to the water inlet or emptying the rain barrel at least every 10 days to prevent mosquitoes from using the rain barrel as a breeding site. Some people add purchased, treated water to the rainwater they collect in their cistern. This may make the treated water less safe. If you collect and store rainwater for drinking, you have an and are responsible for ensuring that your water is safe. You should have your water and your system tested regularly and maintain the properly. When rainwater is used as a supplemental water source, homeowners should ensure that rainwater cannot enter pipes containing safe drinking water. Contact your for more information. Your local health authorities might provide additional guidance on safely collecting rainwater. Rainwater collection is not allowed in all places. Some states consider rainwater the property of the state and regulate its collection, so you should consult with your local government (for example, your or ) before proceeding. : Rainwater Collection

What is the purpose of rainwater harvesting?

The main purpose of rainwater harvesting is to save and conserve water for future use.

What is rainwater harvesting 10 points?

Basic configuration of domestic rainwater harvesting system in Uganda. Rainwater harvesting ( RWH ) is the collection and storage of rain, rather than allowing it to run off. Rainwater is collected from a roof-like surface and redirected to a tank, cistern, deep pit (well, shaft, or borehole), aquifer, or a reservoir with percolation, so that it seeps down and restores the ground water.

Dew and fog can also be collected with nets or other tools. Rainwater harvesting differs from stormwater harvesting as the runoff is typically collected from roofs and other surfaces for storage and subsequent reuse. : 10  Its uses include watering gardens, livestock, irrigation, domestic use with proper treatment, and domestic heating.

The harvested water can also be committed to longer-term storage or groundwater recharge, Rainwater harvesting is one of the simplest and oldest methods of self-supply of water for households, having been used in South Asia and other countries for many thousands of years.

What is the advantage of rooftop?

1. Happiness – Imagine you’re at work and for your lunch break you decide to leave the office. You take the lift up to the highest floor only to emerge in a beautiful park with incredibly privileged views. Doesn’t sound too bad, does it? Rooftop gardens provide contact with nature in places where that has become a bit of a luxury, such as in big crowded cities.

According to a study by the University of Exeter Medical School, having regular contact with nature and green spaces in urban areas can help to keep you mentally healthy and aid with your overall happiness. In addition, because of the decreased pollution levels and the increase in water and air quality provided by rooftops, demands for health care and stress could be reduced.

Less stress levels also mean happier and more productive employees and therefore easier employee recruitment for companies.

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Which pipes are used to collect rooftop rainwater?

20 Dec, 2008,4 mins read Gutters are pipes around the edge of the roof (usually sloped roofs) that collect and transport rainwater from the roof. Downtake pipes are cylindrical pipes that transport the water down, directly from the roof or from the gutters, until the storage tank. Gutter shapes and materials Gutters implemented for sloped roofs can be of different shapes semi circular ‘U’ Shape Rectangular Trapezoidal ‘V’ Shape The semicircular and trapezoidal shaped gutters offer least resistance and result in optimum flow. Their wider mouth reduces wastage of water by splashing. Semi circular gutters are usually preferred since other shapes are not easily available and this one can be easily created by slicing a PVC cylindrical pipe in half.

  • Rectangular, trapezoidal and V shape gutters are usually made from Zinc sheets.
  • Common material for downtake pipes are ultra-violet treated Poly Vinyl Chloride (PVC), Galvanized Iron (GI), Cast Iron and asbestos cement.
  • Downtake pipes will be present in most buildings, leading rainwater to the ground.

Older constructions would have asbestos cement pipes but more recent ones would have PVC, and in a few cases GI downtake pipes. PVC pipes are preferred since they are

lightweight cost effective do not rust are easy to procure, install and repair and allow for increased flow rates because they are smoother than their metal counterparts

It is advised to use IS Quality pipes. Figure 4.1: Different methods of fixing gutters to walls Installation of gutters and downpipes Installation of gutters and downtake pipes is very important.

At the inlet to a downtake pipe from the roof surface, a wire mesh screen or grating may be present to keep out leaves and other debris. It is recommended that these screens and gratings be installed only if the rooftop is cleaned regularly. Otherwise there are chances of leaves and other debris clogging the grating and water stagnation on the rooftop. If grating is not present, the filter must be able to handle the debris that comes down from the rooftop.

Figure 4.2: A gutter clogged with leaves and other debris

Gutters must slope towards the downtake pipe, so that there is no water stagnation. A slope of 1/16 inch per foot to 1/8 inch per foot in the direction of the nearest vertical downtake pipe is recommended,

Figure 4.3: Different ways of fixing gutters to downtake pipes

Gutters need to be well supported so that they do not sag or get dislodged during heavy rains. Good quality U or L clamps must be used for the same and the gutters should be clamped to the wall every two to three feet to prevent damage during heavy rains. Improperly fixed clamps can cause sagging gutters leading to water stagnation and leakages. Water leaks can then spread to the building walls as well.

Figure 4.4: Inadequate support leading to dislodged gutter

To save on piping costs, flat roof catchment discharge points can be linked by a horizontal downtake pipe running just below the roof, instead of bringing downtake pipes from the roof to the ground at each discharge point and linking them at the bottom. A vertical downtake pipe common to three or four discharge points can be led downwards. A similar slope and clamping as recommended for gutters should be implemented in this case as well.

Figure 4.5: Fixing of downtake pipes just below the roof level

Vertical downtake pipes need to be clamped to the wall using U clamps / brackets. For long sloped roofs, splash guards on gutters are useful to prevent wastage of water. A gutter or downtake pipe should not be run horizontally for more than 60 ft. without a vertical downtake pipe. Many buildings may have grooves and extensions for architectural aesthetics. Since it is not advisable to introduce a large number of bends to lead the pipes along these grooves and extensions, L angles may be used to clamp the pipes at a distance from the wall.

Figure 4.6: Use of L angles to fix gutters and downtake pipes

It is advised that lead based sealants not be used to join gutters and downtake pipes. All metal components used to fix the gutters and downtake pipes (clamps, angles etc.) should be properly painted after a protective coat of primer. This will ensure that they do not rust and give way.

Figure 4.7: Clamping and painting of angles and other metal fixtures Sizing of rainwater downtake pipes for roof drainage

The diameter of the downtake pipes varies depending on the roof area to be drained and the peak intensity of rainfall. A bell mouth inlet at the roof surface is found to give a better drainage effect. Gutters should preferably be smaller or the same size as the downtake pipes, depending on the number of gutters that lead into one downtake pipe.

Source: Rainwater Harvesting – Trainers’ Manual published by Karnataka Urban Infrastructure Development and Finance Corporation Chapter 5

Which states use rooftop water?

Tamil Nadu is the first and the only state in India which has made roof top rainwater harvesting structure compulsory to all the houses across the state.

Is roof rainwater good for plants?

Other Uses for Roof Runoff –

Roof runoff has many outdoor uses. Unless the zinc content is particularly high, it is safe to use on lawns and ornamental gardens. Use it to wash cars and outdoor equipment and to rinse patios, sidewalks and decks. You can also use it to saturate the soil that surrounds your vegetable garden. This keeps dry soil around the garden from wicking water away from the vegetables when you irrigate.

Where is rainwater harvesting used in India?

Rainwater harvesting (RWH) is a simple method by which rainfall is collected for future usage. The collected rainwater may be stored, utilised in different ways or directly used for recharge purposes. With depleting groundwater levels and fluctuating climate conditions, RWH can go a long way to help mitigate these effects.

  1. Capturing the rainwater can help recharge local aquifers, reduce urban flooding and most importantly ensure water availability in water-scarce zones.
  2. Though the term seems to have picked up greater visibility in the last few years, it was, and is even today, a traditional practice followed in rural India.

Some ancient rainwater harvesting methods followed in India include madakas, ahar pynes, surangas, taankas and many more. This water conservation method can be easily practiced in individual homes, apartments, parks, offices and temples too, across the world,

  1. Farmers have recharged their dry borewells, created water banks in drought areas, greened their farms, increased sustainability of their water resources and even created a river,
  2. Technical know how for the rooftop RWH with direct storage can be availed for better implementation.
  3. RWH An effective method in water scarce times, it is also an easily doable practice.

Practical advice is available in books written by Indukanth Ragade & Shree Padre, talks by Anupam Mishra and other easy to follow fun ways, Read our FAQ on Rainwater Harvesting and have many basic questions answered.

Which village households have adopted the rooftop rainwater harvesting?

In Gendathur, a remote backward village in Mysore, Karnataka, villagers have installed rainwater harvesting system to meet their water needs. Nearly 200 households have installed this system and the village has earned the rare distinction of being rich in rainwater.

Which city in India is doing rainwater harvesting?

Ahmedabad (Gujarat) – The Ahmedabad Urban Development Authority made rainwater mandatory for all buildings spanning over 1500 meter squares to construct percolation wells, to store the harvested rainwater, and one well for every additional 4000 m sq. covered in 2002.