Some 800,000 people have been displaced and over 350 have died in the worst flooding in a century in southern India's Kerala state, as authorities rushed to bring drinking water to the most affected areas.
At least two trains carrying about 1.5 million litres of water were moving to the flooded areas from the neighbouring states of Madhya Pradesh and Maharashtra, Indian railway official Milind Deouskar said, according to the Press Trust of India news agency.
Thousands of rescuers were continuing efforts to reach out to stranded people and get relief supplies to isolated areas by hundreds of boats and nearly two dozen helicopters, said P.H. Kurian, a top disaster management official in Kerala.
He said weather conditions had improved considerably and expected the nearly 10,000 people still stranded to be rescued by Monday.
An estimated 800,000 people were sheltered in some 4000 relief camps across Kerala, Kurian said.
Weather officials have predicted more rains across the state until Monday morning.
The downpours that started on August 8 have triggered floods and landslides and caused homes and bridges to collapse across Kerala, a picturesque state known for its quiet tropical backwaters and beautiful beaches.
Officials estimate that more than 9900km of roads have been damaged.
One of the state's major airports, in the city of Kochi, was closed on Tuesday due to the flooding and is scheduled to remain closed until August 26.
The Indian government said a naval air base in Kochi will be opened for commercial flights starting on Monday morning.
India's prime minister Narendra Modi inspected the flooded landscape from a helicopter on Saturday and met with the state's top officials, promising more than $US70 million ($A96 million) in aid.
While the central government has dispatched multiple military units to Kerala, state officials are pleading for additional help.
Officials have put initial storm damage estimates at nearly $US3 billion.
Australian Associated Press