The Times of India          24.08.2013

Ahmedabad Municipal Corporation taps to pour turbid water

AHMEDABAD: For the next 55 days nearly 11 lakh residents in the new west zone will have to bear with turbid water in their municipal water taps. These areas include Sarkhej, Vejalpur, Bodakdev, Kali, Satellite, Jodhpurgam, Ghatlodiya, Chandlodiya and Ranip.

The turbidity is largely because the water supply department is carrying out replacements in the filtering systems of its Gyaspur water treatment plant. Colloidal particles cause turbid water which are vegetative particles in river water, instead of mud, claim AMC officials. The officials claim that WHO has put the tolerable turbidity limits between 0 and 5 Nephelometric Turbidity Units (NTU), while the new west zone water supply has a turbidity of 3.5 to 4.2 in its water supply today. On non-monsoon days the turbidity is less than 2 NTU.

When asked whether such water is fit for consumption, AMC city engineer Tarun Lad said, "The turbid condition is because of vegetative particles that float in Narmada water, which travels 66 km before it reaches the Gyaspur plant. The water is fit for drinking and free from disease causing microorganisms. We had tried putting alum to allow the colloidal particles to settle, but there is a lot of flow in Narmada waters. Alum takes at least an hour to fasten the settlement process."

At home one could collect the water in a clear bucket or utensil and allow sediment to settle. Add alum cubes that would help hasten this process. Once the sediments settle, one could also boil the water before consumption.

The filter repair process at Gyaspur is a massive job. The AMC is replacing several layers of sand and aggregate filter along with the special Lamela filters - which are used to separate sediment particles from water. "It will take 13 days more to replace the sand media filter and few more days to replace the Lamela filters. It's been seven years since the filters were changed," said Lad.

"If the turbidity levels are higher, the risk of people developing gastrointestinal diseases is also high. One should boil such water before consumption. Contaminants like viruses or bacteria can attach themselves to mud or other solids and more time will be required for treating of water. Treating water with chlorine in large storage water tanks by residential societies will be a must. Adding alum to the water will help settle the suspended particles," said general physician Dr Dipesh Chaoudhary.