Supply of drinking water to lakhs of people in Tripura — disrupted for the last two days after drilling waste polluted the Howrah river — was restored to normal on Thursday, an official said.

"There is no cause for panic now. Normal water supply has been restored in Agartala Municipal Corporation, adjoining Ranirbazar Municipal Council and Jirania Nagar panchayat areas," Drinking Water and Sanitation Department Chief Engineer Bishu Debbarma told reporters here.

"We have taken remedial measures. The river water was tested before we resumed supply of drinking water through our four major water treatment plants in Agartala and adjoining areas," he said.

The Water Resource Department and Pollution Control Board experts are regularly testing the river water before supply.

He said potable drinking water was supplied to affected areas on Wednesday and Thursday through water tankers.

According to officials, drilling waste containing chemicals and oils from the ONGC's (Oil and Natural Gas Corporation) abandoned drilling site at Mandai (in Baramura hill ranges) had spilled into Howrah river since Tuesday, leading to river pollution.

Tripura Chief Secretary Sanjeev Ranjan held a meeting with ONGC's Tripura operation chief S C Soni and asked him to take precautionary measures to prevent recurrence of such incidents.

An ONGC spokesperson said the company had finished drilling works at Mandai around a week ago and carried out effluent treatment before covering the waste with high-quality plastic sheets.

"Locals, however, cut plastic sheets in order to take away the waste, leading to spillover into the nearby Howrah. Recent rain might may have further worsened the situation," the spokesperson added.

Meanwhile, as the Howrah, like other Tripura rivers, flows into Bangladesh, officials of the Assistant High Commission of Bangladesh here informed their government about the development and are monitoring the situation.

"We have informed about the spillover to the Water Resources Department in Dhaka for suitable action," said Assistant High Commissioner Mohammad Shakhawat Hossain.