I've had a CamelBak backpack for years (a Rim Runner that I bought in 2005), and for Christmas treated myself to a new MilTac H.A.W.G. as one of the zips on the old Rim Runner was starting to break and, well, I wanted something new.
I'm very pleased with the backpack, but one old issue persists; the 3l of water just isn't enough on 4+ hour hikes in hot weather (I'm in Australia, so it's summer here).
Has anyone had any success adding a second hydration reservoir to a pack? Is there typically space in the main reservoir pocket?