if you can find a source for the MRE hot beverage pouches they make a good water transport bag if you are using micro pure or ClO2, and fold flat

a DIY version is to use a vacuum food saver bag... I cut mine to match the length of the sealing bar...double seamed it... depending on volume you want (probably a liter to use the pills) you may not be able to get two per bag section (I used about an 8" section)

I use a 4"x7" heavy duty zip pouch (folds in half, easily fits unobtrusively in cargo pocket) that will hold 350ml liquid to carry some OTC meds, povodine wipes,hemostatic gauze, ClO2 tabs, cloth knuckle bandages,water pouch, along with the signal mirror from an AMK

I used some heavy duty clear packing tape to attach the AMK mini compass to the bottom of a full size Bic lighter

I have an inexpensive ChiCom head light on my bicycle, powered by 3 AAAs...that has a reasonably bright strobe cycle... also the rear red blinking warning light might be considered