This adapter attaches directly to the pour-spout of a Scepter water container. The other end connects to an inexpensive water pump (like this one: https://www.amazon.com/dp/B07KW4TPNG?ref=ppx_yo2ov_dt_b_fed_asin_title). It should work with any water pump that is designed to connect to a standard 5-gallon water jug.

Through trial-and-error, I figured out that the threading for the Scepter pour-spout is an ACME 1 ¼ screw thread (Class = 2G). The other end of the adapter is a simple 20.4 mm hole.

Part prints just fine using PETG, thread side down, with no supports.