I recently had my bathroom renovated. I am more than satisfied with
everything that was done, but I did have some significant concerns
about the workmanship from the plumber on the job. He was consistently
late coming in and screwed up too many times to count.

That being said, I have noticed that I get a short stream of yellow
water from the cold water tap (2 seconds) when I first use it after
several hours. I have two sinks, and it only occurs at the one sink.
I also know that the they used the white 1/2" plumbing tubes to run the
plumbing during the renovation and not copper, if that makes a
difference.

The sink, faucet, EVERYTHING in the bathroom is new. 3/4" plastic
tubing was run up to the bathroom from the basement to feed the
bathroom. The only place copper was used was for the shower install.

Would anyone have an idea of what might be causing this? Is this
something the plumber may have done, is it bad materials? Could it be
the faucet?

Thanks for your response
Bill