Global water aid projects have significantly expanded access to clean water in underserved regions. The recent $40 million TeamWater campaign built hundreds of wells in more than 20 countries, including Bangladesh, Colombia, and Nigeria (1, 2). These gains are impressive, but the wells can tap into shallow aquifers that are easily polluted by agricultural runoff, septic tank leaks, industrial waste, and seawater intrusion. Today, at least 1.7 billion people use drinking water sources contaminated by fecal matter, which can include groundwater sources (3). Without protective measures, wells intended to improve health could instead cause harm.
