This pack will end up having a slightly higher capacity than my Patagonia hybrid pack vest. Which although the hybrid is great, I’ve struggled a little bit if i need to carry an extra layer in it in addition to a rain jacket. The Zimmerbuilt will be able to do that especially if hiking in farther from where the car is parked as it frequently happened in Idaho. Fortunately the week we were there the weather was Texas-like and i had no need for extra layers. I know from living in Colorado that won’t be the case. As you, I don’t carry a bladder either. I use either the steripen, a katadyn befree or the sawyer mini.