Of the 11,437 water samples tested during the week from April 18 to 24, two were found to contain nil residual chlorine. The Water Board has sent these samples for bacteriological examination.

The residual chlorine nil sample were detected in the 359 samples tested by the Institute of Preventive Medicine. The 2,838 water samples tested by the Institute of Health System and the 8,240 samples by the Water Board were found to be wholesome.

A HMWSSB press release said rectification work would be undertaken on the unwholesome samples. During the week the Metro Customer Care section of the Board received 78 complaints of water pollution of which 72 were rectified. Samples collected from houses in Moosabowli, Gazibanda, Umda Bazaar and Shibligunj were found wholesome and the parameters within permissible limits, the release said.