Tanka water meets WHO standards

ahmedabad: this might come as a surprise to many. in a survey conducted by khadia itihas samiti, with the help of ahmedabad municipal corporation, it has been found that the water stored in the tankas or the in-house water storage wells in the houses of the walled city meets the standards set by the world health organisation (who). the khadia itihas samiti's survey had found that between khadia gate and bala hanuman temple, there were as many as 65 tankas in 16 pols, out of which 16 were selected for the survey."water was sampled from 11 of these tankas in the amc labs and it was found that it not only matches the who standards, but is somewhat better. the water was found to be crystal clear, non-saline, soft, almost without any chemical content. as sun-light does not penetrate in the tankas, the water was found to be without bacteria and hence, there cannot be any water-borne disease after drinking this water. also, the water was highly recommended for both cooking and washing utensils," says ashutosh bhatt of the khadia itihas samiti. for instance, while according to who standards, the highest desirable level of sulphur dioxide is 20.00, the level found in some of these tankas is as low as 12.5; the desirable level upto which the colour of the water can go is rated at five by who, in the tankas surveyed, on the other hand, the water was found absolutely colourless. similarly, the ph content as prescribed by the who is seven to 8.5. the level found in the tankas was between 7.1 to 7.9. bhatt says that the samiti is planning to take to report to the state government and urge it to revive the tankas. "now with every household having taps, most of the tankas remain unused and yet, the water was found to be pure." in fact, one of the tankas hasn't been used for 70 years. technology, for us city-bred people, usually means gadgets, pipes, factories and mechanical contrivance. more often than not, we are unmindful of the fact that seemingly simple technology can be based on absolute scientific principles. and if it is traditional technology, evolved in accordance to the local conditions, it stands more chance to be effective than a modern and a mechanical one. a case in point is the tanka. the tanka is perhaps the easiest way devised to store rain water. rain water, in the old houses of the city's pols, flows through a copper drainage system, the mouth of which has a copper strainer. the water is then stored in a deep well, which is made of a particular variety of limestone. with both copper and limestone acting as purifiers, the water does not contain any impurities. the technology is more than 300-year-old and had probably originated in greece. each tanka has the capacity of storing about one lakh gallon of water, which is enough to last a year for a family of 10 members. bhatt says that there are treatise which say that while certain nakshatras like mula and jeshtha are not favourable to store rain water, there are others such as ashwini, rohini, krutika, purva phalguni and others which are favourable for water harvesting and storage. "heavy rains are the ideal time for rain-water harvesting," he says, adding that now israelis are adopting this technology. hopefully, the amdavadis will also re-adopt this age-old technology.