Rainwater Harvesting | WGIC Bangalore 2018

Rainwater Harvesting

What is Rainwater Harvesting?

As the name suggests, Rainwater harvesting is the accumulating and storing of rainwater for reuse, before it reaches the groundwater tables. Rainwater harvesting systems channel rainwater from the roof into storage via a system of gutters and pipes. These systems are easily made from simple local materials. Rainwater may be contaminated due to pollutants like micro organisms, etc. but it can be used to flush toilets, wash clothes, water the garden, wash cars, etc. After treatment the water is considered suitable for drinking also.

Overflow from rainwater harvesting tank systems is used at times to refill aquifers for the purpose of groundwater recharge. There are various types of rainwater harvesting systems from very simple to the complex industrial systems. The first flush of rainwater after dry spell should be allowed to run waste as it will be polluted with dust, etc.

Groundwater recharge, a process where water moves downward form surface water to ground water, occurs anthropologically i.e. artificially when rainwater is harvested and routed to the subsurface. Groundwater recharge is an important process for sustainable groundwater management, since the volume-rate abstracted from an aquifer in the long term should be less than or equal to the volume-rate that is recharged.

Benefits of Rainwater Harvesting:

Environmental benefits
- Provides an effective stormwater management tool
- Recharge groundwater
- Significant reduction in reliance on water storage dams and ground water
- Reduce the use of drinking water for landscape irrigation
- Reduces off site flooding
- Reduces nutrients and sediment going into rivers and streams
- Increases local stream flows during low-flow periods
- Reduces the contamination of surface water with sediments, fertilizers, and pesticides from rainwater run-off resulting in cleaner lakes, rivers, oceans, and other receivers of stormwater and thereby improves water quality

Economic benefits
- Reduces cost for multiple occupancy buildings incurred due to high demand for toilet flushing water, washing vehicles, air conditioner coolant, fire suppression, industrial processes, landscape irrigation and water for housekeeping purposes
- Reduces the use of energy to pump out ground water
- Buildings having large roof areas are conducive for rainwater harvesting and therefore financially viable
- Saves up to 80% of the treated drinking water in a business or commercial building
- Adds life to equipment dependent on water to operate, as rainwater does not produce corrosion or scale like hard water

Property Benefits
- Gains eco-home rating for the property
- Solves drainage problems on the property
- The system can be retrofitted to an existing structure or built during new construction
- Flexible in nature allowing for expansion, reconfiguration, and relocation if need be

Social Benefits
- Supply of water is assured independently during water restrictions