1. Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720, United States
2. School of Public Health, University of California, Berkeley, California 94720, Unites States
3. Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, North Carolina 27695, United States
4. Civil and Environmental Engineering, Tufts University, Medford, Massachusetts 02153, United States
5. Infectious Disease Division, International Centre for Diarrhoeal Disease Research Bangladesh, Dhaka, 1212, Bangladesh
6. Department of Civil and Environmental Engineering, Stanford University, Stanford, California 94305, United States
7. Woods Institute for the Environment, Stanford University, Stanford, California 94305, United States