Abstract Contamination of drinking water with toxic arsenic affects more than 170 million people worldwide. Because arsenic is tasteless, colorless, and odorless when mixed with water, almost all people consume it unknowingly and suffer from health impairments (like skin-related diseases or cancer). Running a randomized controlled trial with 2,334 Indian households, we show that providing inexpensive information how to reduce exposure to arsenic contamination in drinking water has significant ef