Rain water harvesting structure


Rain water harvesting structure


How can we learn from governments around the world?.

Many states and municipalities have started to require rainwater harvesting or incentivise it. Santa Fe County, New Mexico, requires passive rainwater catchment for smaller homes and active rainwater harvesting systems for larger homes. The state of Arizona offers tax incentives to individuals and corporate entities for water conservation systems. The state of Texas has enacted a state sales tax exemption on the purchasing of water conservation equipment. The community that stands out as the leader in rainwater harvesting regulations is Tuscon, Arizona, where “all new commercial development shall include a rainwater harvesting system” and “50% of the estimated yearly landscape water budget shall be provided by rainwater harvested on-site”


Save the silver drops

Rain Water and It’s Harvesting

Water is the basic need
For all, irrespective of type or creed
Animals and plants of any breed
Thrive on this essential liquid feed

Bhagirath, our mythology says
Sits on a penance and prays
For Ganges to set her grace
On earth to make it a heavenly place

Ganges water descends for common good
The human race gets enough food
All other needs of a livelihood
And all living things plunge into a merry mood

Similar is the situation when it rains
This heavenly nectar cures all our pains
For each raindrop, which is for our gains
There is a Bhagirath among us on penance

Rain is indeed a hard earned wealth
Shows righteousness to be in good health
We will be fair and do way with matters of filth
So that it rains for days in a year one fifth

We need to create means to harvest
This natural gift, even if to invest
As its storage will prove its best
When sun turns harsh and the rains resist

Rain water harvesting shows our wisdom
We will face water shortage seldom
And it paves way for freedom
From wars waged on water in the kingdom


Structures for rain water harvesting that can be used in Delhi

Simple roof top Systems

Roofs made of corrugated iron sheet, asbestos sheet or tiles can be utilised for harvesting the rainwater. Gutters and channels can be fixed on the edges of roof all around to collect and transport the rain water from the roof to the storage tank. Gutters can be prepared in semi-circular and rectangular shapes. Locally available material such as plain Galvanized Iron sheets can be easily folded to required shapes to prepare semi-circular and rectangular gutters. Semi-circular gutters of PVC material can be readily prepared by cutting the PVC pipes into two equal semi-circular channels. Bamboo poles can also be used for making gutters if they are locally available in sufficient quantity. Use of such locally available materials reduce the overall cost of the system.

For Thatched Roofs : Step by step approach

* * *

If the roof is thatched, polythene sheets can be used for collecting the rainwater

The collected rainwater is filtered through a filter filled with pebbles in the bottom and coarse sand on the top

The filtered water is collected either in storage tank of existing sump and the overflow water may be diverted to percolation pit nearby.

For Sloping / Tiled Roofs : Step by step approach :

* * *

In a slopped/tiled house the rainwater from the roof is collected through the gutter in the roof.

The collected water is filtered through a filter filled with pebbles in the bottom and coarse sand on the top.

The filtered water is collected either in a storage tank or existing sump. Over flow water may be diverted to an existing open well / bore well or percolation pit.

For common houses with RCC roof : Step by Step approach

* * *

In houses with sloping roofs the rain water may be collected to the half cut PVC pipes fitted along the sloping sides and it may be directed to either sump/open well/bore well or recharge well.

Check the weather the rain water drain pipes extend up to the bottom of the building.

Interconnect the rainwater drainpipes if there exist more than one.

* * *

To collect rainwater in a sump construct a filter champer of size 2/1/2′ * 2/1/2′ * 2/1/2′

The bottom half of the filter chamber has to be filled either with broken bricks/bluemetal/pebbles and followed by one feet of coarse river sand. A nylon mesh has to be provided in between the two layers. The top portion of the filter chamber should be convered with RCC slab.

The inlet rainwater drain pipe should be on the top of the filter chamber and the outlet pipe connecting the filter chamber to the sump should be at the bottom.

* * *

Surplus spill over water from the sump may be connected with the existing open well/borewell or to the recharge well.

In the absense of sump,filter champer may be connected to the existing open well / borewell.

In the absense of sump,open well and bore well the rain water may be recharged through percolation pits and the bottom of bit should be in the sandy formation.

Individual houses Existing Open well

Rainwater from the terrace is diverted to the existing open well using PVC pipes through a filter chamber

The minimum size of the filter chamber is 2.5′ x 2.5′ x 2.5′ filled with broken bricks/ blue metal / pebbles and sand on the top.

The chamber may be covered with RCC slab


Ferro cement tanks Or Rain Barrels

The Structural Engineering Research Centre (SERC), Ghaziabad, has done research and development on a large number of low-cost structures and implements like water/grain storage containers, irrigation channels, biogas digesters and septic tanks, primarily using ferro cement. SERC scientists are imparting training in Ferro cement technology to rural artisans under the National Drinking Water Mission.

Ferro cement containers can be used to store grain and seed, apart from water. Tanks of 1000-2000 litre capacity can be constructed with ease, which are much cheaper than masonry, RCC or plastic tanks. These are easy to repair, and can be easily transported because of their sturdy nature. Such containers have been used on a wide scale since about the past 25 years in Thailand, Malaysia and some African countries. Ferro cement containers with capacity as much as 5000 litres have been constructed in Thailand.

Ground Water Dams

Groundwater dams are structures that intercept or obstruct the natural flow of groundwater and provide storage for water underground. They have been used in several parts of the world, notably India, Africa and Brazil. Their use is in areas where flows of groundwater vary considerably during the course of the year, from very high flows following rain to negligible flows during the dry season.

The basic principle of the groundwater dam is that instead of storing the water in surface reservoirs, water is stored underground. The main advantages of water storage in groundwater dams is that evaporation losses are much less for water stored underground. Further, risk of contamination of the stored water from the surface is reduced because as parasites cannot breed in underground water. The problem of submergence of land which is normally associated with surface dams is not present with sub-surface dams.


Rain Water Harvesting- Introduction

It isn’t easy to come up with ‘one size fits all’ instructions for building rainwater harvesting

systems because of variations in styles of roofs, downspouts, storage tanks, and garden layouts.

You have to use a combination of research, common sense, ingenuity, and dumb luck to design

and build your system.”

-Lenny Librizzi, Assistant Director of Open Space Greening at GrowNYC

Rain water harvesting (RWH) is the means of collecting and storing rain water in large, durable

containers, usually, collecting from rooftop gutters. RWH systems come in a variety of shapes

and sizes. Rain water harvesting systems are fairly easy to construct.