What aspect of water supply does backflow prevention primarily protect?

Backflow prevention primarily protects the integrity of the water system. This is crucial because backflow can allow contaminants from non-potable sources to enter the clean drinking water supply, potentially leading to serious public health risks. The integrity of the water system refers to the maintenance of its safety and quality, ensuring that the water remains free from pollutants and hazardous substances. By preventing backflow, the system is safeguarded against cross-connections that could compromise its reliability and the health of consumers. This focus on preventing contamination underscores the importance of backflow prevention as a critical component of water supply management.