Rainwater collection in multistory roofs

Rainwater harvesting in small houses.

 tank used in rainwater harvesting.

Now we will talk about the rest of the process in this post.

First Flush Pipe

• Debris, dust & dirt collect on the roof during non rainy periods when the first rain arrive. 
• A first flush system arrangement is made to avoid the entering unwanted material into the Filter media & storage tank.
• This is a simple manually operated arrangement or semi-automatic system with a valve below the ‘T’ junction. --------------------------------------------------------------------------------------------------------------------

Filter Unit 

• The filter unit is a container or chamber filled with filter media such as coarse sand, charcoal, coconut fibre, pebbles & gravels to remove the debris & dirt from water that enters the tank.
• The filter unit is placed over the storage tank or separately. 
• It may be of Ferro cement filter unit, Aluminium, Cement rings or Plastic bucket etc.   

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Storage Tank

• It is used to store the water that is collected from the roof through filter.
• For small scale water storage plastic buckets, jerry cans, clay or cement jars, ceramic jars, drums may be used. 
• For larger quantities of water, the system will require a bigger tank with cylindrical or rectangular or square in shape constructed with Ferro cement or cement rings or plain cement concrete or reinforced cement concrete or brick or stone etc. 
• The storage tank is provided with a cover on the top to avoid the contamination of water from external sources. 
• The storage tank is provided with pipe fixtures at appropriate places to draw the water to clean the tank & to dispose of extra water. 

 Size of Storage Tank is based on:-

• No. of person in the House hold
• Per capita water requirement
• No. of days for which water is required

Roof catchment

• The roof of the house is used as the catchment for collecting rain water.
• The style construction and material of the roof effect its suitability as a catchment.
• Roofs made of corrugated iron sheet , asbestos sheet, Tiles or Concrete can be utilized for harvesting the rain water.

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Gutters

• Gutters are channels fixed to the edges of roof all around to collect & transport the rainwater from the roof. 
• Gutters can be made in semi-circular and rectangular shape with cement pipe, plain galvanized iron sheet, PVC pipes, bamboos etc.
• Use of locally available material reduce the overall cost of the system. 

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Down Pipe

• It is the pipe which carries the rainwater from the gutters to the filter & storage tank. 
• Down pipe is joined with the gutters at one end & the other end is connected to the filter unit of the storage tank. 
• PVC or GI pipe of 50mm to 75mm (2 to”) are commonly used for down pipe.
• Bamboo can be also used wherever available and possible.

The roof catchment are selectively cleaner when compared to the ground level catchment.

• Losses from roof catchment are minimum.
• Built & Maintained by local communities.
• No Chemical contamination & only required filtration.
• Available at door step with least cost.

Rain water harvesting system ------
The typical roof top rain water harvesting system comprises:-

• Roof catchment
• Gutters
• Down pipe & first flushing pipe
• Filter Unit
• Storage Tank 

let's talk about these one by one--

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ATTRIBUTES OF GROUNDWATER 

• There is more ground water than surface water.
• Ground water is less expensive and economic resource.
• Ground water is sustainable and reliable source of water supply.
• Ground water is relatively less vulnerable to pollution.
• Ground water has usually high bacteriological purity.
• Ground water is free of pathogenic organisms.
• Ground water needs little treatment before use.
• Ground water has no turbidity and colour.
• Ground water has distinct health advantage as alternative for lower sanitary quality surface water.
• Ground water is usually universally available.
• Ground water resource can be instantly developed and used.There is no conveyance losses in ground water based supplies.
• Ground water has low vulnerability to drought.
• Ground water is key to life in arid and semi-arid regions.
• Ground water is source of dry weather flow in rivers and streams.
  

Rainwater harvesting – Methodologies

• Roof Rain Water Harvesting
• Land based Rain Water Harvesting
• Watershed based Rain Water harvesting

 For Urban & Industrial Environment –
   Roof & Land based Rainwater harvesting.

•         Public, Private, Office & Industrial buildings
•         Pavements, Lawns, Gardens & other open  space

Rain Water Harvesting– Advantages 

1.Provides self-sufficiency to water supply.
2.Reduces the cost for pumping of ground water.
3.Provides high quality water, soft and low in minerals.
4.Improves the quality of ground water through dilution when recharged.
5.Reduces soil erosion & flooding in urban areas.
6.The rooftop rain water harvesting is less expensive & easy to construct,            operate and maintain.
7. In desert, Rainwater harvesting only relief.
8. In saline or coastal areas & Islands, rain water provides good quality water.

What is rain water harvesting ?

It is the activity of direct collection of rain water.
Rain water can be stored for direct use or can be recharged into the ground water aquifer.

Rain Water Harvesting - process of collecting, conveying & storing water from rainfall in an area – for beneficial use.

Storage – in tanks, reservoirs, underground storage- groundwater

Rainwater harvesting - yield copious amounts of water. For an average rainfall of 1,000mm, approximately four million litres of rainwater can be collected in a year in an acre of land (4,047 m2), post-evaporation.
As Rainwater harvesting- neither energy-intensive nor labour-intensive
It can be a cost-effective alternative to other water-accruing methods. With the water table falling rapidly, & concrete surfaces and landfill dumps taking the place of water bodies, Rainwater harvesting is the most reliable solution for augmenting groundwater level to attain self-sufficiency.