After trying many different alternatives over the years, I’ve settled on using several 2 litre Platypus Platy Bottles. They’re really bags, not bottles, completely collapsible when empty and easily molded to fit into tight spaces unless they’re completely full. Although the nominal size is 2 litres, they actually hold closer to 3 when full. They don’t impart any taste to the water and are quite sturdy. I’ve gotten well over 100 days out of use out of each of the ones I now have and probably more than 200 days for the two I bought first. Over that time there’ve only been a couple of small punctures and those have been easily fixed with a bit of duct tape, which adheres well enough to make a “permanent” repair. They’re available at MEC and many other places.
I like using multiple smaller containers for several reasons. First, I can bring more or fewer depending on the length of the trip. Second, it’s easier to fit several small containers into my boat than one or two larger ones. And, third, if one springs a leak or I don’t quite close the cap properly, I don’t lose all of my water supply. Once, before I used these, one of the two larger bags I was using was dropped as gear was being loaded at the beginning of the trip and burst. Before we had even gotten on the water I had lost eight litres of water in an instant, half of what I was planning to use for the whole trip.