Originally Posted by Ford Idaho
When the holes for fittings are cut in the tank/s it is not cleaned out.
So it gets in water lines. filters and your wallet.
I had the white crud after the first, second, and third season. Only used the fresh water tank for a couple of flushes now and then on the road. Never ran it through the water heater so don't think that it is plastic, in mine anyway. I think of the crud as 'fall out' but in reality I think it is minerals that get excised from the water by the heating element and how hot it gets. It's the same as the crud that develops in your home water heater. You are suppose to drain your water heater at home yearly to get rid of this stuff.
NOTE: Just read up on several other RV forums and "Crud" is the official name for it. Also the crud is minerals from the heat of the heating element and some recommend not leaving the element turned on all the time. For me , I'll just leave it on and flush my water heater tank.