Yesterday, I was in this public restroom, and I went to wash my hands. When I first turned on the faucet the water had a yellowish brownish tint to it. Then the water went back to clear. What was this? EWWWWW!
If there was work done recently on the plumbing, rust sediment may have been dislodged, not unlike the tint seen in water when the water authority is flushing hydrants. Essentially harmless.
That is pretty common. I took a bath in a hotel a little while ago and the same thing happened. I drained it after a little while and there was light sludge. A little while later it cleared up. It was from construction.
Usually it’s due to the magnesium bar in the water heater being completely disolved. It’s there to precipitate free ions that damage the pipe. Actually, all pipes have some residue when they sit. In copper pipes it’s a blue-green tinge. The one you don’t see is lead, present in nearly every faucet, due to a strong lobby in Washington. It’s a known problem that saves the manufacturers less that a dollar per faucet, but that’s how D.C. works.
You should always run water until it’s clear. And you should only use the cold water for anything you will eat or drink.