The answer to 'P-trap rusty water' is that a rusty p-trap is a common plumbing issue that can cause discolored water. The p-trap is the curved pipe under a sink that helps prevent sewer gases from entering the home. Over time, the metal in the p-trap can corrode and rust, leading to rust-colored water coming from the faucet.
Some common causes of a rusty p-trap include hard water, chemical buildup, and age. Symptoms include reddish-brown water, a metallic taste, and sometimes a foul odor. In many cases, the p-trap will need to be replaced to resolve the issue. This is generally a DIY-friendly repair, but if the pipes are difficult to access or the problem persists, it's best to call a professional plumber.