Leaders and storm drains connected to a combined sewer shall be trapped. Individual storm water traps shall be installed on the storm water drain branch serving each conductor, or a single trap shall be installed in the main storm drain just before its connection with the combined building sewer or the public sewer. Leaders and storm drains connected to a building storm sewer shall not be required to be trapped.
Storm water traps shall be of the same material as the piping system to which they are attached.
Traps for individual conductors shall be the same size as the horizontal drain to which they are connected.