I have a similar RO external, (2000?) but I think the last owner may have used vinegar to clean it as it was starting to craze when I picked it up and it looks horrible now, but it still skims like a tornado in a trailer park.
Once acrylic starts crazing it just keeps growing /spreading through out the piece. I have heard that heating and bending acrylic can cause crazing and this could be the source of crazing, perhaps? I presume they heat these to make the cones and flares in the plastic. Still holds water.