Twelve inmates of the Alipore Women’s Correctional Home complained of stomach ache and vomited on Monday, sources in the correctional services said.

All of them were admitted to the jail hospital.

Senior officials said the cause of the illness was yet to be ascertained and that majority of the inmates recovered by Tuesday.

An engineer of the water supply department of the Calcutta Municipal Corporation said on Tuesday water samples were collected from Sashi Sekhar Bose

Row in Bhowanipore, where several people allegedly fell ill last week after drinking water supplied by the corporation.

The samples have been sent for tests. The reports are expected on Wednesday.

“We have been digging soil and checking for probable leaks in the pipeline. We have not found any leaks till now. Water bowsers were sent to the locality today to ensure no one panicked and there was adequate supply of drinking water,” the engineer said.