I happened to visit the Rain Center, Chennai (Mandavelipakkam) where passionate individuals are creating awareness about Rain Water Harvesting & enabling people to implement the same in their premises.
What is Rain Water Harvesting?
Our cities are expanding quickly and the density of population per sq. KM is increasing drastically due to high-rise buildings/apartments coming up almost everywhere. This will put a lot of pressure on the water table in that region as people draw more and more water from the well/deep bore. Corporation water/tank lorries maybe available at some places but only a certain amount of water can be supplied by them, and the cost of water supply is often steep.
Rain Water Harvesting consists of various techniques that can be implemented by individual house owners and apartment complex owners to catch the rainwater falling in their premises and either use it (or) send it back to the ground, thereby replenishing the water table of that region. This will save rainwater from going to the sea (through stormwater drains) or evaporating.
Why harvest Rain Water?
Basically, rainwater is harvested to -
- To replenish the ground water table to make sure that you have enough water to draw from the wells, throughout the year.
- To dilute iron salts in brackish water (if your ground water happens to be brackish) and provide clear water.
- To avoid flooding of low-lying areas, as rain water in and around the house is diverted to the ground.
How to harvest Rain Water?
The Rain Center, Chennai has many educational posters that convey the importance of RWH and how to conserve rain water. They have published a small booklet on the topic, ‘Rainwater harvesting in urban areas’. More than all that, people here are eager to consult/explain how people can implement rainwater harvesting in their homes/offices.
How are they harvesting rain water in their own premises?
Look at the above photo. A pipe drains the rainwater from the terrace. But since the initial few minutes of rainwater maybe impure, water from initial rains is held in the left side pipe (Named ‘First Flush’) and can be drained out later on. When this pipe is filled with water, the rainwater enters the neighboring pipe (they are interconnected on the top) which is then allowed to pass through a filter (which contains some gravel/river sand).
This water is then allowed to pass through a sump (the above photo shows just a model, not a real sump), where some water can be stored and drawn directly for usage. This is optional, and rainwater from the terrace can directly be allowed to fall into the well too.
Rainwater can also be harvested from the area around the house, near the gate, and even outside the gate. Have a look at the rainwater drain they have constructed just inside the gate -
So, rainwater, instead of running outside, rushes into the holes shown above from where they are directed into a recharge well (shown below). Rainwater from just outside the street is also diverted into this recharge well.
You may not be able to see inside the recharge well (from this photo) – it is similar to a normal well (with cement rings around the edges), but the depth is lesser. In this case, it is 10 feet deep but the depth varies based on the region. It seems, this well should extend just beyond the clay soil in the ground (as clay soil can hold/prevent water from percolating down). You can also construct a recharge bore pit, to send the rainwater to greater depths. But recharge wells are preferable.
I would like to thank Dr. Sekhar Raghavan and Dr. Indukanth S. Ragade for spending a considerable amount of time educating me on this subject and showing me around their premises.
Contact/Address/Further Info: The Rain Center website.
Edited to add after receiving a mail from the Rain Center officials: Our advice comes free, and people can contact us through email: sekar1479[at]yahoo.co.in or mobile 96770 43869.
So, have you implemented rain water harvesting in your house/apartments?