Which of these is a common indicator of water quality issues?

The presence of contaminants is a key indicator of water quality issues because contaminants can directly affect the safety and health of the water supply. These contaminants may include various substances such as bacteria, viruses, chemicals, heavy metals, and sediments, which can impact human health and the environment. Monitoring for contaminants is crucial for ensuring the water meets safety standards set by regulatory agencies and for protecting public health. Detecting these substances early can help in taking corrective measures to address any potential issues.

In contrast, high water pressure, stable temperature, and low oxygen levels may not necessarily indicate water quality problems. High water pressure typically relates to system infrastructure rather than water purity. A stable temperature may suggest consistent environmental conditions, and while low oxygen levels can indicate issues in some contexts, they might not always correlate with overall water quality concerns unless coupled with other indicators.