Collection Process:

Rainwater is typically collected from roof-like surfaces (such as rooftops) and redirected to storage containers.

The collected water can be stored in tanks, cisterns, deep pits (wells, shafts, or boreholes), aquifers, or reservoirs.

Dew and fog can also be collected using nets or other tools.

Applications:

Domestic Use: Rooftop rainwater harvesting provides drinking water, water for domestic purposes, livestock, and small-scale irrigation.

Agriculture: In urban areas, rainwater harvesting reduces runoff impact and flooding. Combining “green” rooftops with rainwater catchments can help achieve sustainable cities and food security goals.

Industry: Rainwater can be used for industrial processes after proper treatment.

Groundwater Recharge: Harvested rainwater can replenish groundwater levels.

Advantages:

Independent Water Supply: Rainwater harvesting provides an alternative water source, especially in areas with unreliable municipal water supply.

Supplemental During Droughts: Stored rainwater can supplement water availability during dry periods.

Cost-Effective: Initial setup costs are relatively low, and maintenance is straightforward.

Environmental Benefits: Reduces runoff, prevents soil erosion, and helps maintain groundwater levels.

Energy Savings: No energy required for pumping water from distant sources.

Limitations:

Quality of Water: Rainwater quality depends on the roof material and atmospheric conditions. Proper filtration and treatment are essential.

Storage Space: Adequate storage capacity is necessary to meet water demands during dry spells.

Initial Investment: While setup costs are low, there’s still an initial investment.

Climate Dependency: Rainwater availability depends on local climate patterns.

Historical Significance:

Rainwater harvesting has been practiced for centuries in South Asia and other regions.

Installations can be designed for households, neighbourhood's, communities, schools, hospitals, and public facilities.