If you ever pull into a RV park that has hard water with lime and rust, go to Dollar Tree and buy a product called "The Works". Cost us $1.30. Just squirt it in the toilet bowel or in and around the sinks and it immediately illiminates the rust without any scrubbing. Just be sure to not get it on your skin and eyes, turn on the vent fan,and wash it down with water after it does its thing. Amazing stuff!