A multi-stage coalescing filter for separating coalesced liquid from an aerosol-containing gas stream, the multi-stage coalescing filter including: an end cap having a chamber formed within; and a plurality of coaxial, nested, tubular filter elements (105a, 105b, 105c) supported upright on the end cap; wherein: pairs of successive filter elements are spaced from each other such that the end cap between pairs of successive filter elements forms respective annular sumps (106, 106') for collection of coalesced liquid separated by the filter elements from the aerosol-containing gas stream as it passes radially through the nested filter elements; the chamber has one or more inlets (107, 107') in fluid communication with the or each sump for receiving the separated coalesced liquid from the sump, and further has one or more outlets (108, 108') for guiding the received coalesced liquid out of the filter; and the chamber houses a porous element (104, 104') which is configured to saturate under contact with the received coalesced liquid so as to allow the received coalesced liquid to flow through the porous element to the outlet while simultaneously preventing the aerosol-containing gas stream from passing through the chamber to bypass the nested filter elements. an end cap having a chamber formed within; and a plurality of coaxial, nested, tubular filter elements (105a, 105b, 105c) supported upright on the end cap; wherein: pairs of successive filter elements are spaced from each other such that the end cap between pairs of successive filter elements forms respective annular sumps (106, 106') for collection of coalesced liquid separated by the filter elements from the aerosol-containing gas stream as it passes radially through the nested filter elements; the chamber has one or more inlets (107, 107') in fluid communication with the or each sump for receiving the separated coalesced liquid from the sump, and further has one or more outlets (108, 108') for guiding the received coalesced liquid out of the filter; and the chamber houses a porous element (104, 104') which is configured to saturate under contact with the received coalesced liquid so as to allow the received coalesced liquid to flow through the porous element to the outlet while simultaneously preventing the aerosol-containing gas stream from passing through the chamber to bypass the nested filter elements. pairs of successive filter elements are spaced from each other such that the end cap between pairs of successive filter elements forms respective annular sumps (106, 106') for collection of coalesced liquid separated by the filter elements from the aerosol-containing gas stream as it passes radially through the nested filter elements; the chamber has one or more inlets (107, 107') in fluid communication with the or each sump for receiving the separated coalesced liquid from the sump, and further has one or more outlets (108, 108') for guiding the received coalesced liquid out of the filter; and the chamber houses a porous element (104, 104') which is configured to saturate under contact with the received coalesced liquid so as to allow the received coalesced liquid to flow through the porous element to the outlet while simultaneously preventing the aerosol-containing gas stream from passing through the chamber to bypass the nested filter elements.