Floods muddy Yamuna, water supply to be hit in South, West ( Indian Express 13 July 2010)

The water quality in areas fed by the Haiderpur and Nangloi water treatment plants is likely to be affected due to an acute water shortage over the next four days following an increase in the Yamuna’s pollution levels. Delhi Jal Board officials said levels of turbidity, ammonia and nitrate have far exceeded the permissible limits, affecting water treatment in the two plants fed by the Western Yamuna Canal.
Officials said floods in the catchment areas during monsoons leads to soil run-off that increases the levels of mud and suspended solids in water (also known as turbidity). Solid surface pollutants and discharge from various sewage and stormwater drains flow into the river, changing the colour of the water to a dark muddy brown.
DJB’s Member (water supply) R K Garg said: “There isn’t much trouble at the moment. Due to increase in turbidity, production at two WTPs fed by the Western Yamuna Canal has gone down by 10 per cent.” The normal turbidity level maintained in Delhi is 25 ntu (Nephelometric Turbidity Units). But on Monday morning, the turbidity levels increased to 2,000 ntu. By late evening, however, the levels came down to 1,800 ntu.
Increase in turbidity, ammonia, and nitrates affects water treatment at two different levels: quality control and technical processing. To treat the quality of turbid water, large quantities of ferric alumina are added to water.
This, officials say, mixes with the solid content in water to make it heavier to settle down. At the processing level, the filters get choked with the solids present in water, which in turn slows down the process. Presence of ammonia changes the odour of water, and large quantities of chlorine then have to be used for disinfection
“The ammonia and nitrate levels in water may lead to stomach problems. Excessive chlorine treatment also makes the water smell bad and gives it a brownish colour. Hence, the residents are advised to boil water before drinking,” the DJB official said.
A DJB spokesperson said water treatment has been affected considerably at the 40 million gallons a day (MGD) Nangloi water treatment plant and 140 MGD Haiderpur plant. “Therefore, water supply in the following areas will be available at low pressure. The situation may prevail for the next three to four days,” the spokesperson said.
All of West Delhi, all Delhi Cantonment and NDMC areas and some parts of South Delhi are fed by these two plants.
Water supply would be affected in Shalimar Bagh, Pitampura, Lawrence Road, Ashok Vihar, Wazirpur, Saraswati Vihar, Rani Bagh, Peera Garhi, Bhera Enclave, Paschim Vihar, Madipur, Jwala Heri Village, Naraina, Khyala, Rohini, Rithala, Mongolpuri, Sultanpuri, Nangloi, Sunder Vihar, Meera Bagh, Vikaspuri, Major Bhupender Singh Nagar, Tilak Nagar, Subhash Nagar, Vishnu Garden, Janakpuri, RK Puram, Vasant Vihar, Moti Bagh and their adjoining area at the command of Palam Reservoir, Vasant Kunj, Munirka, Jawaharlal Nehru University campus, Mehrauli, IIT, Green Park, Safdarjung Enclave, Najafgarh, Uttam Nagar and Dwarka.