GUWAHATI, Nov 25 � Prefer surface water to groundwater to avoid consumption of fluoride-contaminated groundwater, said noted public health engineer AB Paul. He also suggested urgent steps to activate the State Groundwater Authority, which are at the final stage.
Paul, a former chief engineer of the State�s Public Health Engineering Department (PHED), is the man who first detected fluoride in groundwater in Karbi Anglong and Nagaon districts of the State, besides Guwahati�s Matgharia, Bonda areas in the late 1990s. This was the first instance of detection of fluoride contamination of the State�s groundwater.
In 2003, Paul detected arsenic contamination of the groundwater in Barak Valley and Dhubri district. Those were the first cases of detection of arsenic contamination of the State�s groundwater.
Bed rocks: However, in an interview, Paul told this correspondent that it is unlikely that all groundwater aquifers are contaminated with excess fluoride. �We are to delineate the safe aquifers and publish the information for the benefit of the common people,� he said, suggesting that while extracting groundwater, bed rocks are to be avoided as far as possible.
Paul, along with five other scientists from RRL (now North East Institute of Science and Technology � NEIST), Jorhat,�conducted a research on this type of rocks in Karbi Anglong district and found the rocks being embedded with fluoride bearing minerals. That was in 2005.
City aquifers: On the issue of drying up of the city aquifers above the bed rocks due to excessive exploitation of groundwater, he said, �We may recharge the aquifer�through rainwater and treated grey water. This will gradually replenish the aquifer and also save the city from waterlogging to some extent.
�In cities like Guwahati, a person requires safe water at the rate of 135 litres daily, of which 75 per cent water comes out of home as grey water. Kitchens, bathrooms, floor washing, car washing etc., are the sources of grey water. It is classified as waste�water. Grey water can profitably be treated in simple ways and reused for household works, gardening, car washing, ground water recharging etc,� he said.
Remedies: While speaking on the existing fluoride removal systems, he cautioned that ultra violate ray (UV)-based household water filters, boiling, chlorination, ozonization etc., processes do not remove fluoride.
Moreover, on the now popular reverse osmosis (RO) system, he said it removes around 85-90 per cent of fluoride in water with pre-treatment units. But, it requires regular maintenance at high cost. It rejects large quantity of water with high fluoride. Along with fluoride, RO removes simultaneously many essential elements natural water contains. Many scientists term RO treated water as �hungry water.� WHO does not recommend RO-treated water for long-term use.