Which of the following factors may cause water quality degradation in water distribution systems?

Cross connections are points in a water distribution system where the potable water supply can be unintentionally contaminated with non-potable water sources. These connections pose a significant risk because they can allow harmful substances, pathogens, or contaminants to enter the drinking water supply, significantly degrading water quality. Ensuring proper separation and protection against cross connections is vital for maintaining safe drinking water standards.

While biological growth, corrosion, and dead ends can also negatively impact water quality, they do so through different mechanisms. Biological growth often results from stagnant water, which can promote the proliferation of microorganisms, leading to potential health hazards. Corrosion typically occurs in pipes due to chemical reactions between the water and materials in the pipeline, which can leach harmful substances into the water. Dead ends in a distribution system can lead to water stagnation, which can increase the risk of biological growth and water quality degradation. Each of these factors does contribute to water quality concerns, but cross connections have a unique and direct pathway for introducing contaminants, making them particularly critical to manage in a water distribution system.