KOCHI: Several parts of Kochi and suburbs, including Kaloor, Edappally, Paravur, and Aluva, were hit after water supply was disrupted for the past two days due to high turbidity level. The pumping was stopped on Monday early morning after the level of turbidity touched 284 Nephelometric Turbidity Unit (NTU). The unexpected disruption left the residents high and dry. Sanjitha Philip, a resident of Kaloor, said life was thrown out of gear due to water shortage.
"We managed with bottled water for kitchen purposes but we hardly had water left in our storage tank," she said. The discolouration also worried the residents. "There was no water supply for a long time and when it was restored, there was discolouration. We are apprehensive about using it," she said.
According to authorities, the heavy rain that lashed Idukki and nearby areas caused turbidity in Periyar.
"The normal turbidity level for drinking is five NTU, but last day the turbidity level increased to 284 NTU, which was non-treatable. Therefore we had to stop pumping," said Anil Kumar Augustine, assistant executive engineer. He added that the recent North East Monsoon has not increased the water level.
According to experts, the recent floods would have uprooted several trees on the banks, causing sediments and silt to be swept into the river. "The heavy monsoon in upstream areas of the river might have brought in an increased particulate matter to the river," said G Bindu, an environmental scientist.
The turbidity of the river water increases due to the rise in the content of particulate matters that includes sediment - especially clay silt, fine organic, and inorganic matter and other microscopic organisms.
In some cases, self-filtration will help solve the issue but beyond a certain level, it becomes not suitable for drinking.
"The water goes through a series of treatment before reaching the end user, but in some cases, the hidden sediments also cause water discolouration. Turbidity beyond normal levels will require more time for the sediments to dissolve. Adopting techniques of micro-filtration and ultra-filtration is a costly affair," said an expert who researches on water.
Even though the turbidity level has come down, the water supply has not been fully restored.
"Considering the grave situation, we have ensured a safe supply of almost 60 per cent. Since the turbidity has decreased to 110 NPT, supply will be restored within two days," said Anil Kumar.