You can use vinegar and water to clean discolored stainless steel pots.
To clean discolored stainless steel pots with vinegar and water take some vinegar and pour some vinegar into the stainless steel pot.
Then allow the vinegar to sit for a few minutes and then use a sponge or scrub brush to clean the discoloration from the stainless steel pot.
If the discoloration is more severe and stubborn than you can use some vinegar and baking soda and allow it to sit for 10 minutes or so.
Then scrub the stainless steel pot with a sponge or scrub brush and then rinse the stainless steel pot out with water.
The discoloration should no longer be there.