The answer to 'P-trap rusty water' is that a rusty P-trap is a common plumbing issue that can cause discolored water. This is usually caused by corrosion or mineral buildup in the P-trap, which is the curved pipe under a sink or tub that prevents sewer gases from entering the home.
The main symptoms of a rusty P-trap are reddish-brown or yellowish water coming from the tap. This can be caused by iron oxide or other mineral deposits reacting with the water. In some cases, the P-trap itself may be visibly rusted or corroded. If the issue is caught early, you may be able to clean or replace just the P-trap. However, if the problem is more widespread, it could indicate a larger issue with your plumbing system that would require a professional inspection.