How do I clean wood with a flat water proof paint?

I bought water proof paint thinking it would be semi gloss because it's water proof. It says smooth decorative flat finish. How is it water proof though? All the water proof paints I know of are gloss because it keeps the water sitting on it instead of seeping in and allows you to wipe it down easily. From what I know, flat paint isn't easy to clean. It's Behr basement and masonry water proofing paint. You can use it on wood, concrete, and other surfaces.