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Source: A water harvesting manual for urban areas |
COMPONENTS OF A RAINWATER HARVESTING SYSTEM
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.
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.
- Locally available material such as plain galvanised iron sheet (20 to 22 gauge), folded to required shapes. Source: A water harvesting manual for urban areas
- 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. Conduits
Conduits are pipelines or drains that carry rainwater from the catchment or rooftop area to the harvesting system. Conduits can be of any material like polyvinyl chloride (PVC) or galvanized iron (GI), materials that are commonly available.
Conduits are pipelines or drains that carry rainwater from the catchment or rooftop area to the harvesting system. Conduits can be of any material like polyvinyl chloride (PVC) or galvanized iron (GI), materials that are commonly available.
The following table gives an idea about the diameter of pipe required for draining out rainwater based on rainfall intensity and roof area:
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 |
Source: National Building Code
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.
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 | |
TO BE CONTINUED.... :)
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