Photo shows the cap of a USGI water can. The small cap is an air vent, the medium one is an opening for pouring, and the larger one (which the other two are on top of) is for filling.
To tighten the large/main cap enough that it does not leak, I have to turn it far enough that the small and medium openings are not lined up anymore, which makes pouring out of the medium opening difficult. Loosening the large/main cap to line up the smaller ones means that it leaks. Either way I end up with water all over the place. This is for filling water bottles, cooking pots, etc.
This is obviously a “first world problem”, but with so many of these things in use for so long, I figure other people have already figured out ways to optimize their use, and I’d like to hear about it. So, what are your tips and tricks?