Thanks for the question and what I will say is that I have heard that inside the gal fittings they do rust. To what extent and if it can taste in the alcohol im
not sure. I don’t actually have one but I will be making me one soon. I’ve sold a few of these.
But to answer your question brass fittings is the way to go and I would still use the top gal fitting where the bottle goes into as that part won’t affect it at all. You get them from Bunnings and they do screw into brass fittings whether you use thread tape or thread sealant.
My question to every one on this thread is what did you guys do for the inside of the fittings at the point where the alcohol goes down then 90 degree into the tap part ??
what I did was fill the bottom straight thread fitting below the tap with something like foam then I put a big dab or sylicone at that transaction for the alcohol to flow nicely like a ramp so no alcohol sits and puddles there