What is the primary risk associated with untreated surface water?

The primary risk associated with untreated surface water is pathogen contamination. Surface water, such as rivers, lakes, and streams, can easily be contaminated by various sources including industrial runoff, animal waste, and human activity. This makes it a breeding ground for various microorganisms, including bacteria, viruses, and protozoa, which can pose serious health risks if ingested.

Pathogen contamination is critical for water treatment processes because untreated water can lead to waterborne diseases, which are often associated with gastrointestinal illnesses, cholera, and other serious infections. Because these pathogens are typically invisible to the naked eye, they present a significant and insidious threat, making it essential to utilize proper disinfection techniques such as chlorination, filtration, and UV treatment before the water can be considered safe for consumption.

While factors such as mineral content, hardness, and temperature can affect water quality and usability, they do not present the immediate health risks that pathogens do. Therefore, pathogen contamination stands out as the most pressing concern when dealing with untreated surface water.