Is a common wall between a filter and unfiltered water allowed?

The presence of a common wall between filtered and unfiltered water systems is prohibited because it poses a significant risk of contamination. In water treatment systems, maintaining a clear separation between treated (filtered) water and untreated (unfiltered) water is crucial to prevent any potential backflow or leakage that could allow unfiltered water to contaminate the treated supply.

This prohibition is based on public health considerations, as any cross-connection can lead to waterborne diseases and compromise water quality. Regulations and best practices emphasize the importance of design features that ensure a physical barrier between the two, thereby safeguarding against unintended mixing. By maintaining strict separation, water treatment facilities can ensure the safety and integrity of drinking water supplies.