The present invention provides a composite pressure vessel containing a distributor plate. The distributor plate comprises a thermoplastic polymeric disk having a top side, a bottom side, a perimeter edge and a central opening. The disk is provided with a plurality of radial slits, which define fluid flow passages through the disk between the central opening and the perimeter edge. The fluid flow passages through the disk are adapted to swirl fluid flowing through the disk from the bottom side to the top side such that it swirls around the central opening. The perimeter edge of the distributor plate is joined to an inner side of a thermoplastic liner during or immediately after the thermoplastic liner is formed by a blow-molding process or a rotational molding process.