Emergency water treatment with bleach in the United States: the need to revise EPA recommendations.

During emergencies in the United States, the Environmental Protection Agency (EPA) currently recommends using bottled water, or boiling or treating water by adding 1/8 teaspoon (or 8 drops) of bleach to 1 gal of water. This bleach recommendation is internally inconsistent, a relatively high chlorine dose (5.55–8.67 mg/L), and unsupported by evidence. In this study, bleach was added in three different dosages to six waters available to emergency-affected populations in each of six states; free chlorine residual (FCR) and Escherichia coli/total coliforms were measured 1–24 h after treatment. Data were analyzed using four efficacy criteria. Results indicated the dosages in the current EPA recommendation are unnecessarily high to ensure (1) maintenance of FCR for 24 h after treatment, (2) absence of E. coli/total coliforms, and (3) establishment of a CT-factor sufficient to inactivate Giardia lamblia and enteric viruses 1 h after treatment. Additionally, emergency-prone populations did not have the materials ...