Sure you do! You just have to wash the item with the proper stuff to make sure it stays waterproof/breathable. I've got some Nikwax junk that I wash my outerwear with because after a certian period of time the waterproof/breathable coating on the outside of the garment will kind of de-tune. Wash it with the reccomended treatment and your jacket/pants will bead water again.
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Mark Cushman