What is the largest contributor to organic contaminants in drinking water?

Sewage and wastewater are the largest contributors to organic contaminants in drinking water primarily due to the high concentration of organic material they contain. When sewage is released into waterways, it introduces various pathogens, nutrients, and organic compounds that can be harmful to human health if they contaminate drinking water supplies. The treatment processes for wastewater are designed to remove these contaminants, but inadequacies in treatment can lead to overflow events or untreated discharges, further impacting water quality.

One key aspect that makes sewage and wastewater a significant issue is the complexity of organic contaminants present, including pharmaceuticals, personal care products, and other organic chemicals that can resist conventional water treatment methods. These contaminants can have long-term health effects, which adds to the urgency of managing sewage properly to protect water supplies.

While agricultural runoff, industrial discharge, and urban stormwater runoff can also introduce organic contaminants into drinking water sources, they do so to a lesser extent compared to the widespread issues associated with sewage and wastewater systems. These other sources often introduce pollutants that can include pesticides and heavy metals, but the volume and diversity of organic substances found in sewage make it a more pressing concern.