Good drinking water should contain minerals necessary for our body. Fluoride, for example, is one such mineral, which in small proportions is excellent especially for our teeth. The same mineral in excess starts causing harm to the body. If fluoride is in excess of 1.5 mg a litre, consuming such water can cause dental fluorosis and if it is too much in excess, the body faces the problem of skeletal fluorosis. Dental fluorosis is the first visible sign of excess fluoride co nsumption and is shown as white or brown mottled teeth. Pitting of teeth may also occur.
Since most rural habitations and many urban habitations depend on deep groundwater, some method is necessary to check the presence of fluoride. The 11th Plan document recently finalised by the Planning Commission puts the issue in perspective. It says, "there are about 2.17 lakh quality affected habitations in the country with more than half of the habitations affected with excess iron (1, 18,088). This is followed by fluoride (31,306), salinity (23,495), nitrate (13,958) and arsenic (5,029) in that order. There are about 25,000 habitations affected with multiple problems." In Karnataka alone, more than 5,838 habitations report fluoride in excess of 1.50 mg/litre."
Removing fluoride from water
Various methods of de-fluoridation of water are available. These include household-level de-fluoridation using activated alumina to community-level de-fluoridation plants. While these work well under careful supervision and ownership, many have failed to survive the test of time simply due to apathy or difficulties in maintenance.
A recent programme funded by the Government of Karnataka in 60 villages in four taluks has shown promising results.
The programme being implemented by BIRD-K, a NGO, seeks to provide rooftop rainwater harvesting in 5,000- and 6,000-litre sumps in individual households. Further, treated catchments collect water and store them in underground tanks. Efforts are also being made to recharge the shallow aquifer as well as point recharge of deeper aquifers to dilute fluoride concentration in ground water.
People have accepted rainwater and anecdotal evidence suggests that even three months of drinking fluoride-free water mitigates the impact of fluoride on the body. More than 5,300 families are likely to benefit from the implementation of the scheme.
Tap water coming from surface-water sources is generally free from excess fluoride. If, however, a borewell is the source of water used or if water is bought from private tankers, it is a safe practice to check a sample of the water for excess fluoride. A certified water testing laboratory will do a quality test for you with a sample of about two litres. If excess fluoride is detected it must be removed before use for drinking or cooking. Boiling the water does not remove fluoride. A good reverse osmosis system – R.O. system as it is called – can remove fluoride. Check such a system for performance on a regular basis.
Rooftop rainwater harvesting in sump tanks can give us enough drinking and cooking water for the whole year which is free from chemical contaminants such as fluoride, arsenic and nitrates. Taking steps to recharge groundwater through rainwater harvesting methods is also wise. This is the long run measure to reduce fluoride. Shrinking ground water levels have been reported as one cause for the sudden increase in fluoride in ground water. Sustainable use of ground water resources, keeping the aquifers clean and charged and using the dynamic ground water are measures which will go a long way in ensuring water for all in a climate changing world. Water wisdom lies in realising the true ecological value of water and taking steps to protect this precious resource.
The Hindu, December 15th 2007
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