The water shut off valve that is behind your toilet seat or under your sink will last for a long time but it is not immune to rusting, if you have not installed a rust proof valve. However, it is easy to remove rusts that form on the valve with some simple tools.
Step 1 - Preparing the Tool
You will have to use the slip joint pliers on the shut off valve. Wrap its jaws with masking tape to prevent it from making scratches on the valve.
Step 2 - Turning Off the Water Supply
Before opening taking the shut off valve out, turn the main water supply off and drain the pipes. Small amount of water that is left on the valve can be caught with a small container.
Step 3 - Taking the Valve Apart
In order to make a thorough cleaning, you have to take valve apart. You do not have to remove it from the line though. Just remove the valve handle screw and open the packing nut. Pull out the threaded valve stem, noting carefully the position of the washers.
Step 4 - Cleaning the Valve
Sand off any rust that are on the surface of the valve. If rust is present on the inside as well, wash it out with water and some cleaner.
Step 5 - Cleaning the Washer
Rust may adhere to the neoprene washers as well. Clean them off with a rag and work them carefully to make them flexible once again.
Step 6 - Replacing the Valve
Once you have removed all the rust and dirt on the valve you can put the valve together again by reversing the disassembly process.