Starting to plan for a trip next spring, where we'll probably have to carry a significant supply of drinking water. I'd say something like 10L in addition to 2x2 bottles (my wife and I). I'd prefer to have the water on my bike.

How would you go about it?

Currently leaning towards purchasing 2x6L MSR Dromedary, stored at the bottom of panniers (one bladder per bag to maintain balance). OR 1x10L secured on top of the rear rack, if it can be reasonably done.

It would also be possible to purchase bottled water and save something like 60$ on bladders that will rarely be used afterwards.