Often times. regular toilet bowl cleaners or bleach can not entirely remove the rust streaks that drip down the sides of a toilet bowl. The best solution to remove the discoloration is with CLR product. This agent is potent. You should wear gloves or avoid CLR from touching your skin.
However it is easy to use and does not take long to work in your toilet bowl. Simply squirt CLR directly into bowl, angling it up to the top of the rim. Let it sit in bowl for 5 minutes. Then take a hand held brush that you can reach to the awkward angle of the toilet bowl rim and scrub around the rim slowly making it around and down the sides of the inside of the toilet bowl.
This cleaning method should only need to be done 2-4 times a year. As routine toilet cleaning should keep the streaks at bay.