An apparatus for use in a multi-purpose piping system that provides water to both domestic uses and to fire sprinklers, the apparatus comprising: piping having an inlet and an outlet; a detector, located between the inlet and outlet, that distinguishes between a fire sprinkler water flow and a domestic use water flow; and a drain connection located between the inlet and the outlet. A multipurpose piping system using the apparatus in a system incorporating at least one fire sprinkler, the piping system also supplying at least one other use in the structure.