What equipment do I need to fill a PCP?

You need one of three things: a high-pressure hand pump rated to 3,000 or 4,500 PSI, a scuba/SCBA tank with the right fill adapter, or an electric HPA compressor.

Hand pumps are the cheapest entry but are physical work and pull moisture into the gun if not filtered. Tanks are fast and convenient but need to be refilled at a dive shop or paintball store. Compressors are the most convenient and most expensive, and they need regular maintenance of filters and seals.