What is required for troughs to prevent short-circuiting during backwash?

To effectively prevent short-circuiting during backwash, having troughs that are spaced and level is essential. When troughs are level, they ensure that the flow of water is uniform across the entire surface, which minimizes the potential for channels of faster flow that can disrupt the filtration process. This uniform flow prevents scenarios where water might take a shortcut through the system, bypassing the filtering media and reducing overall efficiency.

Additionally, spacing the troughs properly is crucial. Adequate spacing allows for the even distribution of water during the backwashing process, ensuring that all areas of the filter are adequately cleaned. This spacing and leveling work together to create a more stable and effective operation, thereby enhancing the backwashing efficiency and maintaining the overall performance of the surface water treatment system.