A water crisis in India's capital will take up to two weeks to fix, authorities warned Tuesday as taps ran dry, days after protesters sabotaged a canal to demand better treatment for their caste.

Jat caste groups called off their protests on Monday after the government in the northern state of Haryana accepted their demands following days of riots, arson and looting that saw thousands of troops deployed.

New Delhi's water board was battling to restore full supplies to the city of 17 million people which relies heavily on the canal running through neighbouring Haryana.

Water trucks fanned out across the teeming city, with many households without a regular water supply four days after the canal was badly damaged.

Delhi Water Minister Kapil Mishra tweeted that tap water was being restored in parts of north, central and Old Delhi on Monday evening.

"Tomorrow morning (Wednesday) most areas to get piped supply...supply limited till canal repaired," Mishra said.

"Delhi Jal Board (Delhi Water Board) team already at site of damaged canal. Two heavy earth moving machines (of the board) at site along with senior engineers," he added.

But with just four of the city's nine water treatment plants operating, rationing of supplies to many areas was continuing.

"We are hoping to restore partial services in the next two to three days and 100 percent supply within next 15 days," said senior water board official Neeraj Semwal.

"North, west and south Delhi districts were severely affected by the water shortage with thousands of households not getting regular water supplies."

India sent troops to secure the canal after protesters, demanding a quota for their Jat caste in public service jobs and higher education, seized it on Saturday and diverted the water flow away from the capital.

Although schools and many businesses reopened Tuesday as supplies were partially restored, many were still suffering after the water board said it had been forced to limit supplies.

- 'Never imagined such problems' -

Retired journalist K. Jagannadha Rao said he and his neighbours scrambled to fill as many buckets and drums as they could after waiting 24 hours for a tanker to arrive.

"We have been having a lot of problems with the piped supply for the last three days. There are 110 flats in our complex and everyone has been facing problems," the 73-year-old told AFP.

"We never imagined we would have to face such problems."

About 400 million gallons were being produced after the attack compared to the usual 820 million gallons a day, according to local media.

Many neighbourhoods have supplies piped to their homes, while others still rely solely on tankers to deliver water for cooking and washing.

The crisis has underscored the vulnerability of the Indian capital, which receives little rain for much of the year and has long struggled to provide enough water for its rapidly growing population.

Thousands of troops were deployed to Haryana on Saturday with orders to shoot on sight after week-long protests by members of the caste turned violent, with rioters setting fire to homes and railway stations and blocking highways.

The protests eased on Sunday, after Haryana's government agreed to the Jats' demand for preferential access to sought-after government jobs and university places under India's caste-based quota system.

Curfews have now been lifted in most areas, but some areas remain under a security lockdown.

The Jat caste is the single biggest community in Haryana state, with nearly eight million members.

Many are farmers who have suffered in recent years from falling crop prices and drought, and say their children are facing bleak futures.

India's centuries-old caste system, which divides people into four main classes, has been officially abolished but it still prevails and it remains a hugely contentious issue.

The relatively well-off Patel caste of traders and farmers staged violent protests last year in the western state of Gujarat, with similar demands.