Latest seemingly water/air tight print still leaks under pressure sadly enough. The material itself seems to porous. To clarity, leaking didn't come from between the tube and the connector, but somewhere in a free part.

Ow and we try to use it on a water cooling system, so there is quite some pressure, maybe for other purposes it does work.

But even then it might require some luck, the orientation (z rotation seemed to matter), probably because of the support). In the end I made the walls a bit thicker (a phi of 1.9 instead of 1.61803399). and I increased the fill density from 20% to 30%.

I'll add the latest Cura profile. We use Cura:

http://daid.github.com/Cura/

You still need hose clamps and you probably need to sandpaper the model a bit.

Print at 240C, with 1 shell, and 100% infill, and overextrude by putting in a 2.7mm diameter of filament. This will make this part water tight (we had to try 3 times before it worked)