Then a very small grain of sand that would normally have passed through the system without problems becomes caught in the organic matter. Soon a large build-up of crud forms and the flow is blocked. Each one of those objects went into the hose, so they should have made it through to the canister. But they didn't because they all got caught together. 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.