Two of the major considerations on any long multi day walk are the weight on your back and hydration on route.
I realise that utilising any container to carry fluids will add considerable weight to my pack so have looked at ways to avoid this where possible.
In the main the Grand Traverse of the Alps passes through a landscape that will provide plentiful opportunities to re hydrate. It is only in the last few days in the Southern Alps where there is a need to carry sufficient water to last the whole day.
Given the geography of the route I have decided to use a LifeStraw for water on the majority of the walk as it is both light compared to a full flask or bladder and more compact.
The size is 212mm x 28mm dia including solid sealed caps at either end that protect both the entry and exit of the water.
The only difficulty I have in using it is my own physic! You do need to get close and personal to the water source from which you attempting to drink!
One other aspect of using the LifeStraw that only became apparent on first use is that the water you are drinking can be very cold when it hits the back of your throat.
I will be taking an empty flask or bladder to use on the last section because of the rarity of natural running water there.