How should water supply systems be designed to prevent contamination?

• A. By using larger diameter pipes
• B. By using appropriate backflow prevention devices
• C. By ensuring water pressure is always high
• D. By filtering water before it enters the system

Answer: (B)

Water supply systems must incorporate backflow prevention devices to safeguard against contamination, making the choice of appropriate devices essential. These devices are designed to prevent the reverse flow of water, which can happen if there is a change in pressure within the water system. When backflow occurs, contaminated water from non-potable sources, such as drainage systems or industrial processes, can enter the clean drinking water supply. By utilizing backflow prevention devices, the integrity of the potable water supply is maintained and the risk of contamination is significantly reduced.

While larger diameter pipes might assist in reducing resistance and improving flow rates, they do not specifically address the issue of contamination. High water pressure may help maintain flow and prevent ingress of contaminants to some extent but doesn't directly prevent backflow. Filtering water before it enters the system can enhance water quality, but it does not account for potential post-filtration contamination stemming from back pressure or siphoning effects without the protective measures offered by backflow prevention devices. Therefore, the implementation of backflow prevention devices is critical for designing a resilient and safe water supply system.