10.3.2. Types of Harvesting System

Broadly rainwater can be harvested for two purposes: A. Roof top rain water harvesting (RTRWH) B. Charged into the soil for withdrawal later (groundwater recharging)

Rainwater harvesting is primarily divided into two main categories. The first is the Roof Top Rainwater Harvesting (RTRWH), which involves collecting rainwater directly from the rooftops of buildings. The second is the method of charging water into the soil, which involves allowing the collected rainwater to infiltrate into the ground, replenishing groundwater supplies for later use. This is crucial for managing water resources, especially in urban areas where ground absorption is often limited.

Imagine your roof acts like a funnel during a rainstorm, directing all the rainwater into a barrel. This method helps save water, much like how a sponge absorbs water and retains it for future use.

It is a system of catching rainwater where it falls. In rooftop harvesting, the roof becomes the catchment, and the rainwater is collected from the roof of the house/building. It can either be stored in a tank or diverted to artificial recharge system. This method is less expensive and very effective and if implemented properly helps in augmenting the ground water level of the area.

Rooftop rainwater harvesting (RTRWH) involves using the surface of roofs as catchment areas for rainwater. The rainwater that falls is either collected in storage tanks for use later or redirected to systems designed to help recharge groundwater. This system is cost-effective and can significantly contribute to increasing groundwater levels if installed and maintained properly.

Think of your roof as a giant sponge during the rain, soaking up the water. If you had a bucket underneath that sponge, all that water would collect in it. The bucket represents a storage tank where you keep the harvested rainwater, ready for watering plants or cleaning.

The system mainly constitutes the following sub components: • Catchment, • Coarse mesh, • Gutters, • Conduits or Conveyance, • Transportation, • First flush, • Filter, • Storage, • Supply unit.

The components of a roof top rainwater harvesting system are essential for efficiently collecting and storing rainwater. The catchment area is the roof itself, where rain falls. A coarse mesh helps filter out any debris, while gutters and conduits direct the water flow. The first flush system ensures that the initial dirty water is discarded, preventing contaminants from entering the storage tank. Filters purify the water before it reaches the storage tank, where it can be kept until needed. Finally, the supply unit allows the water to be accessed for various uses.

Imagine you’re straining pasta. The pot is like the roof where the rain collects; the strainer is the coarse mesh that catches bits of food, and the water you pour is similar to how rainwater travels through gutters and into your family's meal preparation. This is how each part works together to ensure you get clean water stored for future use.

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), galvanized iron or corrugated sheets can also be used for water harvesting.

The catchment area is crucial as it is where rainwater is initially collected. It can be made of various surfaces, such as rooftops, which should ideally be impermeable to prevent water loss. Using materials like reinforced concrete or corrugated sheets ensures that rainwater flows directly into the harvesting system without being absorbed by the surface, maximizing collection efficiency.

Picture a large, flat roof on a house after it rains. All the water flows directly off the roof into barrels placed at the edges. If the roof were made of sponge-like material, much of that rainwater would just seep in and be wasted. This analogy highlights the importance of having a solid, smooth catchment surface to optimize rainwater collection.

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