Getting Hard Water Scale in Plumbing, What To Do?

[Jack and Liz Pearce]

Howdy.

I just took apart the solenoid for our coach's Microphor 12 V Commode to see why it wouldn't shut off the water. Water was running into the commode's bowl constantly. The Microphor tech said,"Look for sand in the valve part of the solenoid." I did that and did NOT find any SAND but pieces of scale instead. I am too old and lazy to keep tearing that solenoid apart every two weeks. There must be an answer to solve this hard water scale problem. Ideas, suggestions would be appreciated.
A source of C4 as a permanent solution?

TIA,
Jack
Regards,
Jack and Liz Pearce
Fulltiming in a 1993 Wanderlodge WB40
D'Hanis, TX in the Winter
Buena Vista, CO in the Summer