Disasters are becoming more frequent worldwide and water figures prominently in many of them. Disasters can result from a severe shortage of water (drought, famine) or too much of it (floods, tsunamis). The recent earthquake and tsunami in Japan offers an excellent example of the critical role water can play, given that the Fukushima Daiichi nuclear power plant weathered the 9.0 moment magnitude earthquake well but suffered catastrophic failure from the resulting tsunami. After disasters, water contamination can compound an already miserable situation. This article will discuss the most current literature on the public health implications of water in disasters and offer recommendations for public policy changes to improve water security. Key policy implications include: reestablishment of water and sanitation are top priorities in the immediate post-disaster period; shelters must not be overcrowded and should have adequate latrines; public health education about personal hygiene is critically important along with liquid soap and safe water to clean hands; supplies of water chlorination products and covered water storage receptacles need to be adequately stockpiled before a disaster.