MUMBAI, India — No large city in India offers all its residents a constant supply of water, and most provide water at unreliable times.

The wealthy manage this by paying for tanks, pumping systems and filters, as this chart by Professor Srinivas Chary, the director of urban government at the Administrative Staff College of India, shows. The poor must spend their own precious resource: time.

Among families across India and much of South Asia who receive piped water, the women spend a significant chunk of their days waiting — and waiting — for the water to arrive. They often have to delay or miss going to work or the market or performing other obligations while they wait. Once the water comes, they rush to fill every bucket and container they have.

If the women choose to leave and the water comes during their absence, they may have to wait another five or six days until they get another chance.

A group of graduate students from the University of California, Berkeley, decided to tackle this problem of unreliable water supply by creating a system that harnesses the ubiquity of mobile phones in India and dependability of crowd-sourcing to provide accurate information on water availability.

The students launched a pilot project, called NextDrop, with 200 families in six areas in Hubli, a city in southern India in July 2010. The project was initially funded with $5,000 from the Bill & Melinda Gates Foundation and has since received other grants, according to Emily Kumpel, a Berkeley PhD candidate in civil and environmental engineering who helped conceive of the project idea.

The initiative encourages each group of participating households, who all live in a particular geographic area and receive water at the same time, to send a text message to a central control board as soon as water begins flowing from the faucet.

NextDrop verifies that the water has begun flowing and then sends a message to the rest of the group, alerting them of the water supply.

NextDrop ensures that the information is as fast and accurate as possible by using a modest monetary incentive to encourage participants to be the first to send in information on the water supply.

“This is really a very interesting innovation,” said Emmanuel D’Silva, a Mumbai-based environmental scientist and former World Bank economist who has worked on water projects around the world. He said that combining the use of mobile technology and people’s participation makes for a promising project idea.

So far, the project has been working, and the families have said they no longer have to sit at home waiting for the water to begin flowing, said Hubli-based program officer Madhusudhan B.

The families have also given feedback that will alter and in some ways dramatically change the project going forward.

Women participants told NextDrop that many of them cannot read or send text messages and would prefer a system that includes a voice messaging option, Madhusudhan said.

In the next phase of the project, NextDrop will use a hybrid system that combines inexpensive text messages that blast out information to the group with an automated, interactive voice response system for all one-to-one communication, according to Thejo Kote, one of the Berkeley students who helped plan and now implement the project.

Participants also told NextDrop that they would prefer to receive the information on the water supply 30 minutes to an hour before the water begins flowing.

The students plan on addressing this by collaborating with the local water utility board, which has a schedule by which each area is supposed to receive water. The water timings often do not follow the schedule because of various external factors like electricity problems, corruption or leakage, Kote said.

“Whatever schedules people in the water board may create, it’s very difficult in practice to adhere to it, and the end result is people just don’t know when the water will arrive,” he said.

NextDrop hopes to change that.

Using new technology the group has created, NextDrop plans on collecting information on water delivery directly from the so-called valve men who turn on and off the valves that supply the water to each area. This will provide a close prediction of when the water will arrive.

To add transparency, NextDrop will then use its crowd-sourcing techniques to verify that the water has arrived.

“We can’t ensure reliable and timely water supply. We can only ensure reliable and timely information about when the water will arrive,” Kote said.

NextDrop plans on spending the next 18 months expanding its system to all of Hubli and wants to then bring the idea to other cities in India.

Hubli is one of more than 400 cities in India with populations over 100,000 that face this problem of unreliable piped water supply, according to NextDrop.

Maybe the group will even expand to other services like electricity, Kumpel said.

“I’m excited to provide a service that both helps people and helps utilities do their job better,” she said.

— Follow Hanna on Twitter: @Hanna_India