The answer to 'why is my P-trap low water pressure' is that a clogged or obstructed P-trap is a common cause of low water pressure in a sink or drain. The P-trap is the U-shaped pipe under the sink that holds a small amount of water to prevent sewer gases from entering the home. If this trap becomes clogged with debris, hair, or other blockages, it can restrict the flow of water and reduce the water pressure.
Other potential causes of low water pressure in a P-trap include a kinked or damaged drain line, a problem with the main water supply, or issues with the faucet itself. Resolving the low water pressure often requires identifying and addressing the underlying cause.