Once the emission device is chosen, a system of filters, chemical injectors, pipes, valves and fittings must be constructed to deliver water reliably, safely and efficiently to each outlet, and to facilitate system maintenance.  The following are the major distribution system component categories: Filters Filters are used to remove organic and inorganic debris from the water that could potentially clog the emission devices. In agriculture, sand media filters, screen filters or disk type filters are commonly used, and may be cleansed manually, semi-automatically or automatically.  Even where potable water is used, which is typical of landscaping applications, disc or screen filters should be installed since scale and chemical precipitants may occur which present a potential clogging hazard. Depending on the emission device chosen, the degree of filtration should be 80-200 mesh. Chemical Injectors Chemical Injectors are typically installed in drip irrigation system in order to facilitate system maintenance with chlorine