Which of the following would NOT typically cause issues in a filter bed?

Proper washing techniques are essential for maintaining the effectiveness of a filter bed. When washing is conducted correctly, it ensures that the filter media is cleaned effectively, removing any accumulated impurities and preventing clogging. This process helps maintain the flow of water through the filter and optimizes its performance.

In contrast, poor water preparation, filtered material adherence, and improper wash water application can create significant issues in a filter bed. Poor water preparation can lead to feed water containing high levels of contaminants, which can overwhelm the filtration capacity. Filtered material adherence might indicate that materials are sticking to the surface in ways that affect flow and filtration efficiency. Lastly, improper wash water application can result in inadequate cleaning of the filter media, leading to persistent blockages and reduced effectiveness of the filtration process. Thus, maintaining proper washing techniques is crucial and does not contribute to problems in the filter bed, making it the correct choice.