Why in news? IISc team reported  RO units in Karnataka villages waste more water and pollute source

Highlights:

• RO water purification were mainly Installed to get rid of fluoride and uranium contamination from ground water
• These units generate three times more waste water heavily loaded with the Flouride and uranium that go back to the source that pollute environment
• Many villages in Chikkaballapur, Chitradurga, Kolar and Tumkuru wastewater carry a higher percentage of the same two contaminants
• Waste water is discharged in open channels or drains and seeps into the ground, ultimately recharging the groundwater and further contaminating
• There are also instances where the rejected water is being used for recharging the groundwater
• Key problem was some of the RO units produced purified water with a very low concentration of fluoride, could lead to dental caries upon extended periods of consumption of such water.
• According to WHO and Bureau of Indian standards fluoride, permissible limit in drinking water is in the range 5 to 1.5 mg/l.
• Fluoride concentration below 0.5 mg/l (generated by some of the RO units) leads to dental caries.

Why are this units installed ?

• There are more than 14,000 villages in eastern Karnataka with 80 per cent of them relying on ground water for drinking.
• Water is not only heavily contaminated with fluoride, in 2020 occurrences of uranium in high concentration were found at many sites.
• There is also high arsenic content in part of east Karnataka.

Way Forward

• Government should consider the use of harvesting roof water and sourcing water from perennial lakes (tanks) in the vicinity of affected villages.
• The other possibility is to condense water from the atmosphere, feasibility of the interior parts of the mainland needs to be studied.
• Better maintenance of RO units would improve their performance