Letter to the Editor Response to Wang and Hunter: A Systematic Review and Meta-Analysis of the Association between Self-Reported Diarrheal Disease and Distance from Home to Water Source

1we support their choice of distance to water source as a risk factor to study. It has been neglected lately, in the enthusiasm for studies of water quality. 2 A number of studies of time to water source (TTWS) and quantity of water used at the household level have found that when round trip TTWS is within 30 minutes, which is equivalent to 1 km each way if the average person walks at 4 km/hour, water use is relatively inelastic. However, for sources greater than 30 minutes or 1 km away, water consumption decreases. 3– 5 The studies included in this review involve comparison points much less than 30 minutes or 1 km, which may be insufficient to cause a true difference in diarrheal morbidity. One study that was not included in this review compared groups that have to walk farther than 1,000 meters and less than 100 meters to their water source, and found that diarrheal risk increased with distance to source (unadjusted odds ratio = 3.80, 95% confidence interval = 1.89–4.21). 6