District Chief Medical Officer M.P.S. Verma confirmed this. "Diarrhoea and gastroenteritis cases have shot up. At the outpatient department of three community health centres and 18 primary health centers in Gautam Buddha Nagar district daily about 600 diarrhoea and gastro cases are being reported. At Noida district hospital, about 200 such cases are being reported daily," said Verma.

The 167 nursing homes in the district are getting five cases of diarrhoea. The nursing homes report about 800 cases each day, said Verma.

Verma said another 200 cases are being reported from big hospitals every day .

"Majority of the cases are of mild diarrhoea or gastro. They do not need hospitalisation. In only 10 per cent cases, hospitalisation was needed," said Verma.

Verma said the district health authorities have been directed to take random samples from water supply reservoirs and get them tested. Authorities have also been directed to use chlorine at water sources and clean water supply tanks.

Noida residents said the outbreak was not surprising given the fact that the area continued to get dirty and foul-smelling water.

Federation of Noida Residents Welfare Association president N.P Singh said: "Residents .

from various sectors have complained of foul smelling tap water supply for the first 15 to 20 minutes. Several residents have complained of sand and dust particles in the tap water supply .

Some even complained of small insects." Noida Authority's Chief Maintenance Engineer (water) Yadav Singh said: "Underground water reservoirs were cleaned wherever we received individual complaints. These are cleaned periodically even if there is no complaint. Water samples from reservoirs are regularly tested for E-Coli and other parameters."