Cyclone Hudah struck the northeastern coast of Madagascar in the spring of 2000. Over a 5-month period, 11 700 relief kits consisting of bottles of water disinfectant and foldable jerry cans were distributed to the affected population. Five months after the cyclone, a survey was conducted in 12 villages to determine the impact of these relief kits on water quality. Seventy-six percent of the surveyed households reported using jerry cans, and 65% reported using the disinfectant. Stored water in households using both products had significantly less microbiological contamination than stored water in other households. To improve the prospects for a sustainable intervention, the response plan for future disasters should incorporate a transition to recovery and development, including formative research into local customs, beliefs, and water handling habits, and funding support to initiate social marketing.