Clean Your Plastic Shower Curtain Liner: I have a plastic shower curtain liner that was really dirty with soap scum and mildew. I had read that you could throw these in the washing machine, but I was hesitant since mine was a heavy-duty liner. Well, I should not have been concerned because it really works! I put the liner in the washing machine with some white towels, regular detergent, and 1 cup of vinegar. I had read that the vinegar will remove the soap scum, and it sure did! I ran it through a cycle with warm water. When it was done, I hung it back up on the shower curtain rod to dry. Good as new!