What is Rainwater Harvesting Technique? – PowerPoint Presentation

Rainwater Harvesting is a technique used to collect rainwater from roofs & above surfaces of the buildings and store it for later use. Rainwater harvesting is collecting, storing, filtering & purifying of rainwater for future. It has been adapted in various parts of the world where conventional water supply systems fail to meet people’s needs. It is the best way to collect rainwater that flows off waste.  

Water is natural resource which is necessary for all the living beings to survive in the word. Even though our planet is surrounded by 3/4 parts of water, only 1% of it can be utilised for human use. Water is necessary not only for drinking but also for day to day usage, agriculture, industrial & commercial purposes. Due to the globalisation, contamination and other reasons, water scarcity is developed all over the world. Water is important for the existence of all the organisms in the world. So, it is necessary to conserve water for our self and the future to come.  

Water ratio is balanced by rainfall & evaporation by the nature. Rainwater harvesting is an effective method implemented to prevent water scarcity.

What are the benefits of rainwater harvesting ?

The best part of rainwater harvesting is that it saves time and money. It is a sustainable water management practice that can be implemented by anyone in different levels.

• It can be implemented in less cost.
• It reduce the water bill
• Prevents soil erosion
• Prevents quality & quantity of ground water
• It is easy to implement and operate
• Can get pure water that is free from chemicals

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Components of Rainwater Harvesting

1. Catchment Area

The collection area, i.e., the roof of the building is the first component to collect water.

2. Conveyance system

The gutter is referred as the conveyance system. That is the pathway of the water to flow from roof to the storage area.  

3. First flush & filter

It is used to flush out the first spell of rain to clear the dust particles in the roof and to remove the pollutants. If proper filter installation is not maintained, there is chances of ground water being contaminated. After first flush of rainfall, the water should pass through filters. Filters are used to treat water effectively without contamination and store the water clean. It filters dust, leaves and other organic matters. There are different types of filter. They are sand gravel filter, charcoal filter, PVC pipe filter, sponge filter. The basic function of the filter is to purify water and send pure water to storage system. The type of filter to be implemented depends on testing the density of the soil, cost, nature of surface and intensity of rainfall.  

4. Storage system

  It depends and varies according the building structure, size and material of construction. It can be stored in underground tanks or above tanks. The tanks should always be placed on a stable and level area to prevent it from leaking or collapsing. It can also be allowed to recharge the bore wells or dig wells as a recharge system to increase the quality & quantity of water.  

5. Delivery system

  It is the pump that required to distribute the water inside or outside the building.  

Types of Rainwater Harvesting

There are two types rainwater harvesting:

1. Surface Runoff harvesting

In urban areas water flows away unwantedly into the sea or as surface runoff. This runoff water can be collected and used for recharging system by adopting harvesting methods.

2. Rooftop Rainwater harvesting

The rainwater is collected from the buildings roof and stored to the tank or the recharge system. It is less expensive and is useful to increase the ground water level if implemented in correct manner.

There are various methods of rooftop rainwater harvesting. They are described below.

Storing for Direct use

This is the most cost effective way of rainwater harvesting. In this rainwater collected from the rooftop is stored directly in the tank. The tank is designed accordingly with first flush and filtration system before the storage tank. It is also designed with a overflow control system, so that the excess water can be diverted to the recharge system.
This method is most commonly implemented in houses and buildings. The stored water can be used for secondary purposes as house hold usages. It not only saves rainwater, but also the cost of transporting and distributing water to doorstep. It is useful to conserve ground water and collect rainwater effectively.

Recharging groundwater aquifers

Groundwater can be recharged by draining the rainwater into the borewells, dugwells, pits, trenches or percolation tanks.

Recharging of Borewells

The collected water from the rooftop is send directly to the filtration system. After filtration the water is diverted to borewells to get recharged. Abandoned borewells are also used as recharging aquifers. The first flow of rain should be flushed out to avoid contamination and to restrict clogs.

Recharging of Dugwells

Dug wells can also be used as recharging system. The collected water from the catchment pipes are directly send to the dug wells after filtration process. The filtration can be suggested as done in the bore well recharging system. The dug wells should be maintained by cleaning and desalting in regular intervals to maintain the recharged water quality.

Recharge pits

Recharge pits are smalls pits that are constructed using bricks or masonry walls. The pits can be made of any shape circle, rectangle or square. It is mostly implemented in small houses or buildings. The top of pit can be covered and the bottom is filled with filter medium. The capacity of the pit is designed depending on the catchment area, density of the soil and the usual intensity of rainfall in the area.

Recharge Trenches

The recharge trenches are made where the upper layer of the soil does not allow fluids to pass into. The recharge trenches are dig in the ground and is refilled with stones, small rocks or bricks. It is usually implemented in the surface runoff areas to enhance percolation. It is suitable in parks, playgrounds and roadside drains.

Percolation Tanks

Percolation tanks are artificial tanks that are constructed on land that is highly permeable. It is constructed by earthen materials that allows the water to pass through it. The water then collected is percolated in the ground. It allows to enhance the groundwater quality. Both surface runoff and roof top water can be diverted into percolation tanks. It can be implemented in gardens, open spaces and roadside of urban areas. The collected water can be used for gardening purposes, and other raw uses.

  As a result of harvesting rainwater, the need amount of water is obtained through many operations for industrial wide and house needs without depending on other water sources. It also reduces the soil erosion and floods. It reduces the water bills and also can be implemented in less cost. Chemical free water is obtained for irrigation and watering gardens. Can be used for several non- drinking purposes. With increase in population the water needs are continuously increasing and rainwater harvesting decreases the demand of ground water in the areas of water scarcity.  

Every Drop Counts…