Rooftop rainwater harvesting system.

Rooftop rainwater harvesting system in India.

1. Rooftop rainwater harvesting ( rrwh ) By Abhishek Roll no. 2106950000005

2. Introduction :- Rooftop Rainwater Harvesting (RRWH) is a technique that collects rainwater from a building’s roof. The roof acts as a catchment, and the rainwater is stored in tanks or diverted to an artificial recharge system.
RRWH is a water conservation technique. It can help recharge groundwater levels and provide a source of potable water, especially during dry seasons.

3. Why do we need Rain Water Harvesting ? Water is the reason why life exists on planet earth, without it life is unimaginable. Reports of several global agencies including united nations indicate that if the current situation of water does not change and preventive measures are not taken, then the world will start to run out of fresh water by 2050. Rainwater harvesting is a sustainable process that helps in preserving rainwater for different purposes and for future needs as well.

4. Components of rooftop rainwater harvesting Catchment
Conduits
First flush
Filters
Storage tanks, and
Recharge structures

5. 1. Catchments :- The surface that receives the rainfall directly and transfers water to the system is called catchment area. It can be a paved area such as a building’s terrace . Often usable for water harvesting is a roof made of reinforced cement concrete ( rcc ) , galvanized iron or corrugated sheets.

6. 2. Conduits :- The conduits are pipelines or drains that bring rainwater to the irrigation system from the catchment or rooftop area. Conduits may be of any type , such as polyvinyl chloride ( pvc ) or galvanised iron ( gi ).

7. 3. First-flushing :- A first flush device is a valve which ensures that the runoff from the first rain spell is flushed out and is not entering the system. This needs to be achieved , as the first rain spell brings a comparatively greater volume of air and catchment surface contaminants.

8. 4. Filters :- Sand filters have commonly available sand as filter media. Sand filters are easy to set up and are inexpensive. These filters can be used to treat water to efficiently reduce turbidity (suspended particles such as silt and clay), colour, and microorganisms. The top layer contains coarse sand followed by a 5-10 mm layer of gravel followed by another 5-25 cm layer of gravel and boulders in a basic sand filter that can be built domestically.

9. 5. Storage tanks :- There are different options available for the construction of these tanks in terms of form, height, construction material and tank location and they are: – shape : cylindrical, square and rectangular. Material of construction : Reinforced cement concrete, ( rcc ), ferro cement, 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 .

10. Methods of Roof Top Rainwater Harvesting Storage of direct use. Recharging structure .

11. 6. Storage of direct use :- In this method rain water collected from the roof of the building is diverted to a storage tank. The storage tank has to be designed according to the water requirements , rainfall and catchment availability. It is advisable that each tank should have excess water over flow system. Excess water could be diverted to recharge system. Water from storage tank can be used for secondary purposes such as washing and gardening etc.

12. 7. Recharging structure :- Ground water table can be recharged by various kinds of structures to ensure percolation of rainwater in the ground instead of draining away from the surface. Commonly used recharging methods are :- 1). Recharging of bore wells. 2). Recharging of dug wells. 3). Percolation tank.

13. Advantages of rooftop Rainwater Harvesting Helps in reducing the water bill. Decreases the demand for water. Promotes both water and energy conservation. This technology is relatively simple, easy to install and operate. Reduces the need for imported water. Improves the quality and quantity of groundwater .

14. Regular maintenance is required. Requires some technical skills for installation. Limited and no rainfall can limit the supply of rainwater. If not installed correctly , it may attract mosquitoes and other waterborne diseases. One of the significant drawbacks of the rainwater harvesting system is storage limits. Disadvantages of rooftop rainwater harvesting