Added plumbing to supply water for a sink and refrigerator for our kitchen. The kitchen is adjacent to the garage, so the new plumbing tapped into existing plumbing that supplies water to a utility sink in the garage. This sink was modified/added by the previous owner who used galvanized pipe for the sink's wall mount fixture.
When we found rusty water coming out of the kitchen sink, we hired a plumber. Starting from the utility sink fixture he proceeded to replaced a couple of feet worth of galvanized plumbing until reaching the copper supply, opening the wall has he needed.
Once the job was complete, water from the kitchen sink appeared to be clear. But we've noticed that if some time passes between uses we still get some rusty water. It's improved over the initial problem, but it doesn't seem to be getting any better.
What could be causing this, and how can we remedy this problem?