Abstract: Housings for reverse osmosis filter cartridges and methods of making the same. The housings include: (1) a hollow cylindrical liner formed of a thermoplastic polymer that is adapted to surround a reverse osmosis filter cartridge; (2) a hollow head assembly that includes a transition collar portion formed of a thermoplastic polymer that is joined to said liner and a barrel portion formed of a chopped glass fiber-filled polymer that is overmolded onto said transition collar portion; (3) an end plug that is adapted to be received within an opening in the barrel portion; and (4) an overwrap layer comprising wound glass filaments and a polymeric resin that covers the outer surfaces of the liner and head assembly.