Moderator if I have crossed over on to something already dealt with please delete
I normally repair our dry suits myself. I found lots of information on the net for seal replacement tears etc, however my fabric dry suit suddenly went porous this season and the only information I could find was on this forum from about 2 years ago which had lots of useful posts but no final solution. So I experimented.
Suit is the cheaper fabric type which is made of the same sort of material as your breathable waterproof mountain jacket. I didn't want to use the soap solution test as that might destroy even more water proofing. So I hung it up, inside out in a dark room with a powerful torch inside. The problem area the legs looked like a starry night! lots of sewing needle pricks of light on the seams. The fabric on the legs also let a fine mist of light through on the panels but the still water proof areas did not.
For the pin pricks on the seam I got a tube of some butyl rubber repair solution for boats wetsuits general watersports etc for reference the brand I used was Black Witch which is the standard over here but I guess they are all very similar. squeezed half a tube in to a jar and diluted it with Toluene. It takes quite a bit of working with a brush to dissolve the rubber paste fully into the toluene in order to get a smooth lump free paint. Now Toluene is a benzene derived solvent also called methyl benzene and has a safety data sheet a mile long so read that before playing with it, it is also highly flammable part way between petrol and benzene. My pin pricks were small so I made a solution similar in consistency to auto paint, if they were larger I would have made it thicker, smaller thinner. Reason I wanted the solution to penetrate but still plug the holes but not sit on the surface. With the suit still hung upside down with its light in it and only just enough light to work with I painted out all the stars. Left several days to ensure it had fully dried, in reality most of the Toluene would be gone in minutes. Gone where? this stuff loves pilot lights, sparking light switches and static electric on your clothes and if it finds one of those ignition sources your hard work and dry suit will be gone in spectacular fashion in seconds, you have been warned, find a safe place to do this! Checked suit when dry no stars, looking hopeful.
The faint misting light through the main material panels was progressively worse going down the legs, I figured the water spray had just washed off the waterproofing so I bought a water soluble water proofed for breathable mountain jackets. The manufacturers instructions should be followed, most are the same and advice to wet the cloth first then spray the solution on, allow to fully dry then test. I made the mistake of having the suit two wet the first time and the stuff dripped off. Second time I hung the suit in the shower wet it with the shower and left it for half an hour, then sprayed it. For reference the brand I used was Grangers XT proofer but I don't see why one should be any different to the other brands.
Light test first, then lake. I have used 3 times since I completed a few weeks back and suit is like brand new Total use 22 slalom runs plus some general messing about around lake since undertaking the above repair, zero leakage.
Hope this helps some one save a few dollars.