I have to disagree with some of the above..sorry.
While WW is MF, they serve different purposes. My WW started to deteriorate when I use to wash them with my regular MF. Why? Because regular MF are used for so many purposes involving polymers, oils, waxes, polishes, glazes, silicone dressings, etc.
Put them all in the wash and the WW will absorb a fraction of this chemical soup. Even a minute percentage of these chemicals is enough to cause the WW to become water-resistant.
None of these chemicals suspended in water should come into contact with WW if you want perpetual water adsorbancy.
Additionally, WW don't need regular washing. They only should ever come into contact with clean water. Why are you washing them?
Eventually they'll pickup contaminants and rubber streaks from trim, requiring washing. Wash them separately, treat individual stains with a stain remover, wash in hot water with a TINY amount of detergent, rinse in HOT water with vinegar...and I'll guarantee you they will adsorb indefinitally.