This is a quick tip from WORKSHOP!
The washable Wet-Only Filter has a durable foam outer layer with structural resin core designed to add protection for your vac during high volume liquid pick-up.
Basically, when picking up a lot of water this is the best option.
This wet vac filter Fits: WORKSHOP 5-16 gallon vacs except the WS0500VA
Learn More: http://workshopvacs.emerson.com/shop/en/wsv/vacs-s-all/vacs-s-browse-all/wet-only-foam-filter-%285-to-16-gallon%29-wsv-ws24200f