Yeah, I was thinking of using milk crates, but a carrier that doubles as a wash tub might be nice.
The plastic buckets I carry them in just happen to be sized so 4 2 liter bottles sit EXACTLY in place, with no play, or space for anything other than what you can slip in the middle (bottle brush / scrub brush) and in the area near the top of the bucket. It was one of those lucky finds I suppose.
7 Gallons is a bit heavy. I just keep them filled in my basement as an extra store of water.
The reason I use 2 liter bottles was because I used to have a water cooler for the 5-gallon jugs. I used to HATE carrying those jugs around — especially since I would return and exchange them 10 at a time. I hated just carrying one up from the basement to load onto the cooler — and could not imagine carrying them around on camp trips.
I was going to get a spigot system for them to bring camping (along with re-usable caps etc) — and just got rid of the whole setup, cooler and all once I started filling 2 liter bottles with my Berkey filter.
I remember reading posts by reviewers on Amazon who said that trimming off the flashing on the threads and spigots can stop the leaks, have you tried doing some trimming with a razor blade? I'd be curious if it helps.
Just a thought — have you tried using thread tape on them to keep the threads from leaking? Probably more of a pain than it is worth, but there might me some sort of solution there.
