What is a primary cause of water quality deterioration in distribution systems?

Biofilm growth in pipes is a primary cause of water quality deterioration in distribution systems due to its potential to harbor pathogens and contribute to the formation of harmful chemical compounds. Biofilms are created when microorganisms adhere to the surfaces of pipes, forming a protective layer. This accumulation can obstruct water flow and create conditions where harmful bacteria can thrive.

As biofilms develop, they can release toxins and alter the chemical composition of the water, leading to taste and odor issues. Additionally, biofilms can enhance the corrosion of pipe materials, leading to the leaching of metals and other harmful substances into the water supply. This combination of factors makes biofilm growth a significant concern for maintaining safe and high-quality drinking water in distribution systems.

Other options like low water pressure, high water temperatures, and excessive chlorine usage can also impact water quality, but they do not have the same direct and persistent effect on biofilm development and the subsequent deterioration of water quality as biofilm growth does.