Thursday, March 23, 2006

Rain Water Harvesting : On the Occassion of Water Conservation Day

I'm not an expert on Rain Water Harvesting. But I have interacted with a couple of experts and listened to what they have to say. In the process, I may have missed out on some points or misunderstood a couple of them, I'm sure someone can correct me if so.

Rain Water Harvesting can be broken up into 2 categories.
1. Collecting water during monsoons in a storage device to be used later when the need arises. This would include methods of storage like overhead or underground tanks.
2. Providing a channel for the rain water to recharge the ground water levels.

Most people prefer Option 1 with the opinion that "If I am spending X amount of money on anything, I should directly benefit from it" In reality, Option 2 is better environmentally. The problem is, if you live on a higher ground then the water will accumulate at a lower level. The ground water levels will go up all around but not as dramatically at the higher levels as at the lower levels.

In a city like Bombay, it is extremely important to go in for Rain Water harvesting to recharge our Ground water levels. The shortfall of available water against necessary water is huge and will only increase as the days go by. In other cities like Hyderabad & Chennai because of constant water shortages, most people dig borewells in their back or front yards. I am not too sure of the situation in Mumbai, having just moved here.

Borewells & wells are the best conduits for rain water harvesting from a house with hardly any expense involved. All one has to do at a building that has a well or a borewell is extend the channel (PVC pipes) to direct the rain water that flows down from the terrace or a tiled roof into the existing well. If the water from the well is to be used directly for drinking and cooking purposes, a simple filtration process of channelling the rain water through a large drum with various sizes of pebbles and slightly larger stones (I'm not certain if a chemical treatment is also given, I don't think it is) should do the job.

The rain water of the first few showers is not normally acummulated because they can mix with pollutants in the atmosphere and be harmful. But after the initial showers, the concentration of pollutants decreases and then the water can be safely harvested.

One of the experts I spoke to has worked with a village in Karnataka, where nobody depends on muncipality providing amenities any more. The water they accumulate through rain water harvesting. Electricity is generated through Gobar Gas. They use only natural pesticides not chemicles. They have their own sewage management system. All the villagers participate actively in all activities. They truly live as one community where everyone celebrates every festival as one community.

The moderator of Sproutsonline said:
Usually Urban Water Harvesting is not used for drinking water, but for services cleaning, washing, watering plants, flushing toilets etc. As water health is an important issue and even small level of pesticides & pollutants can be really hazardous.

One of the important problems for Water harvesting is over concentration - like what is being done in housing colonies, the PWD (Roads) and BMC in Mumbai with a venegance - leaving little or no space for the earth to absorb / soak water. One of the first things necessary is to unconcretise some space and put in mud / earth.

Although it may seem very far fetched, reducing polythene bags, can be one of the best ways to get rain water to the soil - After the July 26th deluge, plastics choked not only the drains but also the soil & roots of trees- clearly showing their pest like role in preventing natural water harvesting.

Filling in of old wells & tanks (Mumbai has/had loads of tanks like CP & Gowalia tank, Bandra & Sion Talaos, Banganga etc in the past, which are now filled with garbage) seen in plenty in and around Mumbai is another reason for lack of success in water harvesting in the city area. We need to re-open these wells, a seemingly tough job, but not really so....

Also, at a household level, changing your washers (to ensure zero leakage), watering plants in the evening - so water evaporation is avoided (which happens when plants are wattered early in the day), using spray bottles or cotton threads to water plants trhough drip irrigation rather than mugs and buckets helps conserve water.

Will later post some links in the comments section on urban water harvesting.


ramarao said...

Dear Friend

I get very useful information regarding rainwater storage. Please kindly send me mail regading how to construct rain water storage in home. Presently I am facing sevee water problem.

Please send as early as possible.

Thanking You

Rama Rao P

rain harvesting system said...

Water Conservation is very important task for saving water resources and one of the best techniques of water conservation is rain water harvesting from this technique we can save large amount of rain water.

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