1. Energy & Resources Group, University of California, Berkeley, Berkeley, California 94305, United States
2. Division of Epidemiology and Biostatistics, University of California, Berkeley, Berkeley, California 94305, United States
3. Department of Environmental Science and Engineering, Kathmandu University, Dhulikhel 45200, Nepal
4. Helvetas Nepal, Lalitpur 44700, Nepal
5. Eawag, Swiss Federal Institute of Aquatic Science and Technology, Duebendorf 8600, Switzerland