The same thing happens in your irrigation system. Freshwater clams are very common in city water systems. Or maybe you should take a look in your cat or dog's bowl at what THEY drink without getting sick. Types of Filters Filters are broken down into different categories dependent upon the method used to filter the water. A brief description of the most common types follows.
Screen filters are excellent for removing hard particulates from water, such as sand.
These non-solid materials tend to embed themselves into the screen material where they are very difficult to remove. In other cases they simply slide through the holes in the screen by temporarily deforming their shape. Screen filters are cleaned by flushing them with a stream of water or removing the screen and cleaning it by hand. Depending on the flush method used you will probably have to periodically hand clean the screen to remove garbage not removed by flushing. Several methods of flushing are common.