Exposure evaluation is an indispensable step for the risk assessment of chronic arsenic toxicity. The amount of water intake, which consists of the base of exposure calculation, has been lacking for the arsenic-affected populations in the developing countries. Thus, the purposes of the present study were (1) to estimate the water intake in such population, and (2) to estimate the relative importance of water versus food as the source of arsenic exposure. Adult males and females (n = 19 for each) were selected from two rural Bangladeshi communities that entirely depended on tubewells for their water supply. Their water intake was measured by two methods, a 24-h self-report and an interview with frequent visits. Results of the two methods generally agreed with each other in terms of correlation and the absolute intakes. Mean water intake obtained by the self-report method was found to be around 3 l/day with substantial individual variation (the maximum = 6 l/day), no sex difference, and a significant between-community difference. The calculation for total arsenic exposure demonstrated that there was no sex difference in arsenic exposure except when the exposure was mainly from food and thus relatively low. Although these results need to be further confirmed under various environmental settings, these results suggested that (1) the sex difference in the manifestation of arsenic toxicity previously observed in this area should be related with factors other than exposure level and that (2) the risks associated with low arsenic concentrations of groundwater should be carefully interpreted because food may be providing additional burden of arsenic.