Chlorination of drinking water in emergencies: a review of knowledge to develop recommendations for implementation and research needed

Clean water provision is a critical component of emergency response, and chlorination is widely used in emergencies to treat water. To provide responders with practical, evidence-based recommendations for implementing chlorination programmes and recommend areas for future research, we conducted a literature review of chlorination in emergencies, supplemented with a literature review on chlorination in general. We identified 106 total documents, including 7 with information on technical efficacy, 26 on chlorine dosage, 22 on technical challenges, 21 on product options, 8 on user acceptability, 33 on programmes for emergencies, and 8 on monitoring. We found that: 1) international chlorine dosage recommendations in emergencies are highly inconsistent; 2) high-quality information from the general chlorination literature on challenges of chlorination can be adapted for emergencies; 3) many chlorine products are available for use in point-of-delivery, point-of-source, and point-of-use emergency-response programmes; 4) information on the effectiveness of different chlorination programmes in emergencies varies, ranging from little data available to high-quality data that can inform programming; 5) information on user acceptability of chlorination in emergencies is lacking; and 6) monitoring data on chlorine programme effectiveness in emergencies are lacking. In this manuscript, we provide a summary of knowledge on chlorination in emergencies, recommendations for programme implementation, and recommendations for future research needed to assist communities and agencies responding to the increasing number of natural disasters and outbreaks worldwide.