For water I use collapsible, very light 1 and 2 litre containers like those made by Platypus, Source etc. I find they last a couple of years of abuse. Light and fold up when not in use. PET water bottles you buy in supermarkets with mineral water are also are very light and last remarkably well even when squished. Both will easily last the duration of the AAWT. If I put water into a drop, eg Rumpff Saddle, I buy cheap bottled water to ensure there is no growth of stuff while it is awaiting collection. If you do this keep one or two of the empty bottles for the Barries. Ortleibs are pretty bomber but cost and weigh a lot. I reserve wine bladders for times I may need a lot of extra capacity for a day or so such as this situation. Just emptying one now for the trip
but do make sure the tap is easily removable for filling.
I normally carry a 1 and a 2 litre container as an overnight camp uses about 2-2.5 litres leaving a bit to move on with in the morning. During the day I usually just carry the 1 litre filled unless it is very hot or the distance to the next available water is more than 1/2 a day.
As for digging for water, only ever resorted to it in a sandy river bed, If you come across a clay bank weeping water (quite likely) then there are a couple of techniques that can make accessing that water easier.
1. Push a small stick into the point where the water is expressing angled downward. The water will run down the stick and into your pot.
2. Concentrate the water by scoring sloping channels into the bank just below the water source. Lead these to you stick and thus your pot.
3. if the ground is suitable dig a small pit where the water will collect. It will be muddy at first but soon clear. Very gentle scooping will allow you to harvest the water.
"Perfection is attained not when there is nothing more to add, but when there is nothing more to remove".