I usually have a problem finding decent collapsible dog bowls here - the sort of thing you can easily carry in your pack. The ones I've previously had leaked, and were a little too small to allow two muzzles in at the same time. The solution - I found a silicone rubber flan mould at the local market for the equivalent of 3 Quid. It's about 10 inches across by about 3 inches deep so wide enough for both hounds to drink at the same time. When they've finished drinking it's easy to pour the remaining water back in to the bottle (it's 33C here at present, so I never waste any on a walk). It also rolls up pretty small to tuck into a side pocket on my pack. Job jobbed!