I have a 6 gall wet dry shop vac bye rigid . do i need a foam wet filter on the inside or will it work properly without the filter on i need it for water only. people in the store said the paper filter was for both ? impossible so i keep burning them up and exchanging them anyone have insight ??? home depot said go to sears so basically F U they said.!!!

James the attached link/video shows filter just pulls off. I also put a link to the manual and it show the filter held on with large plastic nut, which would have to be removed first.
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4 Gallon Portable Wet Dry Vac
http://www.ridgidparts.com/pdf/WD40500.pdf

Rigid WD4070 Wet Dry Shopvac Unboxing and Overview
RIDGID Shop Vac Review must have tool 2

The foam filter is for use when using the vac. to pick up water. Now you should have a paper filter for picking up dry material.If possible you may want to look inside of one at the store. Hope this helps.

Keep it on. The purpose is to give you something to clean, a time or two, rather than have to replace the more expensive filter. I know it seems redundant, but all of the pieces filter better than just a bag. Also, if the bag gets any damp or wet material, it breaks and your next filters are the foam and paper filter.

to use for 'wet' use --- just remove the foam and paper filter from the inside of the unit. it is now ready for wet use.
make sure you let the unit dry out before you reinstall the filters and use it for dry use.

c...

Unscrew the 'tab/nut' at the BOTTOM of the filter and pull off the filter cartridge

when picking up dry materials use the foam sleeve that slips on and the blue cloth (assuming there all blue) over it, there should be a ring that slides over blue cloth to hold it in place over the foam sleeve, for wet pick up u can use the foam sleeve minus the blue cloth but let it dry out before picking up dry stuff, you can pick up both wet and dry with a cartrige filter that looks simular to a car air filter and it slips over the foam sleeve, but let it dry out after picking up water before picking up dry cause itll just clog it up

all you have to do is open it up and take the paper filter off and then it's a wet vac. If it has a foam over filter you leave that on

yes, the foam filter is what you should use, also make sure you remove any bag, or paper filter, the water would make it fall apart.

can I run my sears shop vac without the paper bag, for dry pickup?

Just be sure to remove the paper filter bag that fits over the foam filter before vacuuming liquids. It's easy to get it wet and they don't work very well when that happens.