This hub is an answer to a request from Mandybeau (Hub pages). I was asked to explain the ways in which rain water harvesting could be useful and how safe would harvested water be, for drinking and other purposes. I was, perhaps, chosen to answer this request as I (not in the forefront, though) along with my husband and a team of scientists, spent almost a decade, executing rainwater harvesting projects in India. Further details are available at the link given below. The company (Water Solutions Inc) continues to be involved in this noble cause since year 2000.

Before I delve into the subject, it’s important for me to give a passing reference to the need for having water harvesting done (in your backyard). This is a technique used, in most parts of the world, only for the purpose of recharging ground water. Whether we like it or not, it goes without saying that ‘rain’ still ‘reigns’ as the prime and natural resource of water, no matter how many scientific innovations man might have made in the field of 'water augmentation'. As we all know that due to deforestation and the consequent ecological imbalance, the water level beneath the ground is being depleted day by day. Besides, the ever rising demand of water supply, especially from the urban areas, does not match with the surface water sources; as a result, the water reserves beneath the ground level are overexploited. This consequently results in the water level depletion. Water harvesting, apart from recharging the ground water level, increases the availability of water at a given place, at a given point of time. This useful technique has helped people, especially, in the dry and arid zones, where the relentless effort and extensive research conducted in the field of Hydrogeology, has yielded significant results.

Rainwater harvesting is a very ancient technique known to have existed for over 4000 years. It is enjoying a renaissance of sorts in the world, but it traces its history to biblical times. Extensive rain water harvesting apparatus existed 4000 years ago in the Palestine and Greece. In ancient Rome, residences were built with individual cisterns and paved courtyards to capture rain water for augmenting water from city's aqueducts. As early as in third millennium BC, farming communities in Baluchistan and Kutch impounded rain water and used it for irrigation dams. 

It is a process involving collection and storage of rain water (with the help of artificially designed system) that runs off natural or man-made catchment areas e.g. roof top, compounds, rock surface or hill slopes or artificially repaired impervious/semi-pervious land surface. Undoubtedly a number of factors contribute to the amount of water harvested e.g. the frequency and the quantity of rainfall, catchments characteristics, water demands and the quantum of runoff, and above all speed and ease with which the rainwater percolates through the subsoil to recharge the ground water.  It further reduces the run off which chokes the storm water drains, reduces flooding of water on the roads, improves the quality of water and reduces the chances of soil erosion.

Rainwater Harvesting is a way to capture the rain water when it rains, stores that water underground for being used later. This happens naturally in open rural areas. But in congested, over-paved metropolitan cities, we need to create methods to capture the rain water. This technique is being revived now, to give back to Nature that we take from it.   The rainwater that falls on the surface/ roof top is guided to bore wells or pits or new/ old/ abandoned wells through small diameter pipes to recharge the underground water which can be used later, whenever required. 

Rain water harvesting’ is often mistaken for ‘water recycling’ but there is a stark difference in the two processes, in as much as, in the former case, water can be used only for domestic (washing, bathing, laundry etc) and irrigation purposes whereas in the latter, water is recycled and chemically treated so as to make it fit for drinking purpose. This clearly shows that harvested water should only be understood as the stored underground water (primarily obtained from rain) which in the first place, replenishes the ground water level and secondly, makes additional water available for domestic and agriculture usage. The entire process of installation, of technically equipped underground water harvesting structures, has been lucidly explained in the video uploaded herein. It should be able to explain the whole process of capturing the rain water and diverting it through the pipes into the storage tanks, installed beneath the earth surface.

Credit goes to all those scientists who have worked day and night for devising this simple mechanism for giving back to the Nature what we take from it. It’s high time the human race stops exploiting the Natural resources and instead, expresses its gratitude (for the bounties offered by Mother Nature) by thinking about replenishment, for a change.

I am sure a world without ‘Water’ would sound unimaginable and uninhabitable. So, we better start preserving it before we run out of it completely.