The 5 Gallon/20L Reliance Water jugs(Aquapak, waterpak, etc) are durable water storage containers. The spigots and lids, however, are rife with trouble - from being hard to turn off/on or the nozzle not quite aligning to avoid leaks when positioned for dispensing.

There are plenty of cheap USB-C pumps that attach to the more ubiquitous 5 gallon water jugs but nothing for reliance water jugs. I designed the adapter for this style pump in particular.

This print helps adapt the two, squeezing over the reliance jug threads and using a groove built into the pump.
This will probably not fit other pumps than the style pictured but you can always check or request other sizes.
It's plenty flexible as designed so no need to break out 83A or other softer filaments.
PRINT GUIDELINES:
No real print notes other than to use regular TPU 95A filament with no supports.
NOTE ON FOOD SAFETY:
The contact this will have with drinking water in incidental at best - it is not designed to touch water you are drinking while in use.
The pump has a silicone pump hose that touches the water and no part of the adapter is in direct contact with the water when the jug is upright.
Some movement of the jug MAY result in contact. If this is concerning, you can cover the small bit of exposed TPU in tape or other flexible food safe covering.
The author marked this model as their own original creation.