The answer to 'why is my P-trap rusty water' is that a rusty P-trap is often caused by corrosion or mineral buildup in the trap. The P-trap is the curved section of pipe under your sink that is designed to hold water and prevent sewer gases from entering your home. Over time, the metal in the P-trap can corrode, leading to a rusty appearance and potentially contaminated water.
Some common causes of a rusty P-trap include hard water, high mineral content in the water supply, and age/wear of the trap. Symptoms may include discolored or smelly water, leaks, and reduced water flow. To fix a rusty P-trap, you may need to replace the trap entirely or thoroughly clean it to remove any buildup. For severe corrosion, it's best to call a professional plumber to assess and replace the trap.