I had the same problem, although the water I use is severely filtered!
The origin of these ‘scratches’ is mechanical, the so called pressure fog. It is due to the friction caused by rolling on the film after it was exposed, wether it be 120 roll or 35 mm film, or the film sliding over the film guiding rolls in the camera. It is typical for Foma, thus the camera is not to blame (what I thought before). The protective layer on the emulsion side is, to say at least, not one of the best.
There is an other issue that is typical for Fompan : when using plastic reels, to develop the film, there are scratches on both sides, along the film’s length, and on the image. Plastic reels are about double as large as the SS ones. A tanning developer tends to worsen that.
It is really painful to see your photo’s ruined like this!
I shoot Tri-X now and all the troubles went away…

Philippe