Households in Bengal affected by arsenic-laced water are likely to reap economic benefits even if they pay for clean water supply, a study by Jadavpur University has indicated. The study, described by researchers as among the first to assess the costs of arsenic-contaminated water on households, has shown that investing in safe drinking water is economically feasible. "We find that the cost of inaction in areas affected by arsenic is much higher than the investment required to maintain a steady supply of arsenic-free water,' said Joyashree Roy, professor of economics and coordinator of the global change programme at Jadavpur University. Previous surveys have shown that Murshidabad, North 24-Parganas, South 24-Parganas, Nadia, Hooghly and Howrah are among districts with unacceptably high arsenic in groundwater. The Jadavpur School of Environmental Sciences has estimated that more than 4.5 million people in the state are at risk of drinking water with arsenic levels higher than 50 microgram per litre. Roy used an econometric model to calculate that a typical household in North 24-Parganas would incur an expenditure of Rs 297 a month exclusively because of exposure to arsenic-contaminated water. She has calculated that the cost of providing clean, piped water would be about Rs 127 a month for each household. Households lose money not just on the treatment of arsenic-related diseases, she said, but they lose income when people stay home because of illness or when they spend resources to collect arsenic-free water. "This study gives us a figure for the returns that a household would get by investing in getting arsenic-free water,' Roy said. A number of technologies for arsenic removal and methods to deliver clean water to households have been tested in recent years as part of research projects supported by various funding agencies. "But the technologies couldn't be maintained because of lack of sustained investment. And for sustained investment, we need to work out the economics,' Roy said. Her model and calculations have been published this week in the journal, Science of the Total Environment. Roy said that ideally, households should themselves bear a part of the expenses. "A system in which the beneficiary pays even a small part of the investment is sustainable.'