To remove suspended solids, surface water must be?

To effectively remove suspended solids from surface water, filtering is the most suitable method. This process involves passing water through various types of materials that can trap and separate these contaminants, allowing for clearer water to emerge. Filters can be made of sand, gravel, or specialized membranes, and they work by physically obstructing the particles, thus clarifying the water.

In contrast, flushing water simply moves it through a system, which may not remove solids, whereas boiling water is primarily used for disinfection purposes rather than for separating solids. Chlorination also serves to disinfect water, killing pathogens, but it does not address the physical removal of suspended solids. Therefore, filtering is the process specifically designed to target and eliminate suspended particles from surface water, making it the correct choice.