I like the pockets on the new Mariposa rucksack but they have two weaknesses. 1) the zips aren’t waterproof, 2) there are no drain holes to let out any water ingress.
While it’s impossible to make the pocket zips watertight without either sewing a new zip or some rain flaps, it is possible to make the zip fabric less absorbent . Using a small paint brush, I applied some McNett SilNet to the zip material. This should stop water from being absorbed and give some protection.