The answer to 'why is my pressure regulator overflowing' is that the pressure regulator is not functioning properly, likely due to a blockage or malfunction. This can cause the regulator to lose control of the water pressure, leading to excess water flow and overflow.
Some common causes include a buildup of sediment or debris in the regulator, a worn or damaged internal component, or a problem with the water supply line. Symptoms may include high water pressure, leaks, or water spilling out of the regulator. To fix the issue, you may need to clean or replace the pressure regulator, or address any underlying problems with the plumbing system.