Abstract: Mounting assemblies for filter cartridges include a sealing bolt having a threaded shank portion for being threadably engaged with one (upper) end of an interior apertured filter cartridge support post. A head portion of the bolt allows it to be turned manually by a suitable tool to assist in threadably interconnecting the shank and post. The other (lower) end of the support post is rigidly connected (e.g., via welding) to a lower external sealing cup-flange which sealingly bears against a lower end gasket associated with the filter cartridge. The sealing bolt is further provided with an upper sealing cup-flange positioned concentrically around the shank portion immediately below the head portion of the sealing bolt. An O-ring seal is embedded in the lower surface of the head portion so as to sealingly bear against the upper sealing cup-flange when the sealing bolt is threadably tightened with respect to the support post.