This document specifies design principles and performance requirements for preliminary wastewater treatment using screens with a mesh size above 50 microns, at plants serving more than 50 PT. NOTE 1 For micro-screens with a mesh size below 50 microns see EN 12255-16. NOTE 2 The primary application of this document is for wastewater treatment plants designed for the treatment of domestic and municipal wastewater. However, it contains information that can also be useful for commercial and industrial wastewater pretreatment and for combined sewer overflows (CSO). This document applies in combination with EN 12255-1 and EN 12255-10.