Presence of coliform bacteria, an indication of faecal contamination, has been found in drinking water samples collected from bore wells and surface wells of the city.
It was during a water quality analysis that the presence of harmful organisms was detected. The analysis was carried out by the Water Institute of the School of Communication and Management Studies as part of a project for preparing water policy for the city.
Trained volunteers of the Kudumbashree collected water samples from 148 bore wells and surface wells from the city areas. Two samples each were collected form the 74 divisions of the local body for analysis, said Sunny George, Head of the Water Institute.
Water from the surface wells was rarely used for drinking. The piped water supplied by the Kerala Water Authority, water drawn from bore wells and supplied by tanker lorries were used for drinking needs. Coliform bacteria were found in all well water samples.
Since presence of coliform bacteria was reported from water samples collected from bore wells too, experts suggested use of boiled water.
Presence of iron in drinking water from bore wells, which is considered an irritant, was also confirmed in more than half of the water samples analysed. While the permissible limit of iron in drinking water is 0.3mg/litre, it was found up to 15mg/litre in some samples, he said.
Nitrates too were found in increased level. It was found in 24 per cent of the bore well water samples. While the permissible level of nitrates is 0.5 mg/litre, there were instances when nitrate was detected to 9mg/litre.
The mixing of sewage with ground water is attributed to the increased nitrate level in water samples.
Saline incursion has also been a cause of concern in the city as 20 per cent of the bore well water had excess salt. Creation of fresh water zone by rain water harvesting in open wells is one way of addressing the issue. The formation of such zones would resist saline incursion, Dr. George said.
