A combination of a big plastic bladder and multiple nalgenes.
First, big fan of the Platypus Water Tanks.
https://www.platy.com/bottles/platy-water-tank/platy-water-tank.htmlThe great thing about these are the big zipper for gathering the water and the simple no-spigot hole for pouring. Far fewer moving parts to break.
Second, in Philmont, we learned to have a constant rotation system for Nalgene water storage. One Nalgene being actively purified with whatever (tablets, iodine, etc). One purified Nalgene being actively drank from. One or more Nalgenes purified and stashed in the pack. Then you regularly rotate and refill as you pass new water sources.
This all assumes you are procuring a large volume of water on-site to boil for meals and dishwater for a sizable crew. When I'm car camping, I use these square nalgenes for bulk water storage in my floorboard/trunk. The flat surfaces allow them to stack easily.
https://www.amazon.com/Nalgene-Wide-Mouth-Rectangular-Bottle/dp/B004RYWXJQLastly, NEVER go for a camelback or similar tube-based hydration system. They have lots of small plastic parts that wear out or break easily (since you're chomping on the spigot). They're easy to puncture or rupture since they're sitting nested in your pack at full capacity. But the bigger problem is that they are a cleaning nightmare. Those tubes and mouthpieces are a mold fiesta and are difficult to even get clean. These things are a joke - trust the simple unbreakable Nalgene instead.
