It would be better if I get to know some detail description on exact process of implementing the same.

Rain harvesting is a process by which rainfalls are collected to a storage for future use . In this process rainwater is collected from various sources like roof surfaces , parks , roads , open grounds etc and its redircted to a closed storage rather than allowing it to run off.

mainly there are two types of rain harvesting method-

1.surface runoff harvesting 2.roof top rainwater harvesting

surface rainwater harvesting is the method of collecting rainwater flowing along the ground during the rains will be collected to a tank below the surface of the ground for irrigation and other purposes. During storage of rainwater, it is important to incorporate efficient and effective water conservation methods i.e. by reducing evaporation. It is a very easy to adopt technology and very profitable if used accordingly. The main objective of surface runoff rainwater harvesting method is to meet the ever increasing demand of water, to reduce water pollution, soil erosion and flooding of roads.

Rooftop Rain Water Harvesting is the technique through which rain water is captured from the roof catchments and stored in reservoirs so that people can use those water in different purposes.

In rainwater harvesting method we have to follow some steps for harvesting the water . the steps are as follows-

STEP 1: Determine Your Rainwater Harvesting Potential

The rainwater harvesting potential is the amount of rainfall which could be collected in the given area. It is calculated as the surface area you have available to collect the rainwater multiplied by your annual precipitation.The surface that receives rainfall directly is called the catchment of the rainwater harvesting system. It may be a terrace, courtyard, or paved or unpaved open ground. Therefore the catchment is the area, which contributes rainwater to the harvesting system.

STEP 2: Determining the Layout

The layout and the location of the tank, pipelines are determined in such a way as to maximize the use of collection surfaces.

There are several options but the major ones are:

a) Spread out tank option

b) Cluster tank option

STEP 3: Setting up the Storage

The rainwater collected from the roof of the building is diverted to a storage tank. The storage tank has to be designed according to water requirements, rainfall, and catchment availability.

Each drain pipe and collecting system should have:

A mesh filter at the mouth and first flush (also known as roof washer) device which will divert the first flow of water away from the tank. A filtration system before connecting to the storage tank. An air gap to prevent stormwater backflow. Each tank should have an excess water overflow system. Excess water could be diverted to the recharge system

STEP 4: Decide on the Features in the System

1. First Flush Diverters

The first flush is a device used to flush off the water received in the first shower. The first shower of rains needs to be flushed-off to avoid contaminating storable/rechargeable water by the probable contaminants of the atmosphere and the catchment roof. It will also help in cleaning of silt and other material deposited on the roof during dry seasons. Provisions of first rain separators should be made at the outlet of each drainpipe.

1. Filter

Filters are used for the treatment of water to effectively remove turbidity, colour, and microorganisms. After the first flushing of rainfall, water should pass through filters. Gravel, sand, and ‘netlon’ mesh filters are designed and placed on top of the storage tank It prevents silt, dust, leaves, and other organic matter from entering the storage tank. The filter media should be cleaned daily after every rainfall event. Clogged filters prevent rainwater from easily entering the storage tank and the filter may overflow.

1. Limit Sources of Contamination

Check your roof surface materials is suitable for collecting appropriate quality water and trim overhanging vegetation Install gutter mesh to prevent leaves and debris from blocking gutters and pipes 4. Additional features which could be added:

Add a UV filter in case it is to be used for drinking water Gravity feed to tanks Pumped distribution Each tank can individually be emptied for cleaning Recharging of groundwater aquifers Automated irrigation system

STEP 5: Installing the Pipes and Tank

For installing pipes:

Seek the necessary permissions ( if required ) from the authorities to lay the pipes Dig Trenches, if laid underground. It is preferable to have the pipe as a single fall to avoid sediment collecting in places that cannot be reached easily for cleaning. Lay the pipes in trenches or otherwise and connect using connectors.

For installing Tanks, Sump:

Make a tank stand suitable to the property Put the tanks on the stand and ensure that they don’t blow away when empty Connect them up so they can behave as one volume. Recommend putting a valve for each tank mostly for maintenance Install first flush diverters to keep the most contaminated rainwater out of your rainwater tank. Connect some sort of overflow arrangement. If the tanks are in a sump it would require overflow arrangement and lots of drainages. When the overflow is undersized, pumps will flood. Make the final connections between the PVC collector pipes and the tanks. Install a tank gauge to regularly monitor your water level and usage

For installing pumps and managing standing water:

Use a pump to distribute the water or pump it to an overhead tank or for watering the garden etc. The pump should be right-sized or it can be marginally oversized. Adequate pressure must be maintained by using pressure couplings. Put some water in the collectors and check the water flows into the tanks and the functioning of the entire system. For standing water, use a wet-dry valve or first flush in-ground diverter to drain your pipes in between rainfall events Install a solar shield to block sunlight and prevent algae growth