"Four major water treatment plants in the city were closed since yesterday following contamination of water with ONGC drilling waste," water and sanitation chief engineer, Bishu Debbarma said.
"We are trying hard to restore the drinking water supply to the inhabitants," he said.
Drilling waste from a site at Mandai at Baramura hill range, about 40 km from here was kept inside plastic bags near the abandoned drilling site.
Local people cut open the plastic bags to take them away and the waste materials in them were left on the ground. It later mixed with the river after heavy showers, ONGC spokesperson, Sonalee Datta told reporters.
Debbarma said, work was on war footing to remove the waste materials, purify water and restore the water supply.
"We are also consulting experts of ONGC and hope to restore the supply by tomorrow," he added.
Nineteen rivers from Tripura including Howrah flow into Bangladesh.
The Assistant High Commissioner of Bangladesh here, Mohammad Shakhwat Hussain said that the matter was informed to Dhaka for taking appropriate measures.