What is the main purpose of testing water for bacteria?

The main purpose of testing water for bacteria is to identify potential health risks. The presence of bacteria in water can indicate contamination that may lead to disease and health issues, making it a crucial aspect of water quality monitoring. Testing for bacteria helps to ensure that the water is safe for consumption and meets public health standards. This is particularly important in protecting vulnerable populations and preventing outbreaks of waterborne illnesses.

While the other options involve important aspects of water quality testing, they do not directly relate to the health implications that bacteria presence signifies. Mineral content, chemical changes, and pH levels are essential for understanding the overall composition of the water, but they do not specifically address the immediate health concerns that bacteria presence can indicate.