Low pressure in just one shower (while other fixtures are fine) usually means a clogged showerhead, a partially closed shutoff valve, or a failing pressure-balancing valve in the shower cartridge. Start by removing and soaking the showerhead in vinegar to dissolve mineral deposits. If that doesn\'t help, the cartridge inside the shower valve may need replacement. This is a common issue in Southern Maryland where hard water causes rapid mineral buildup in showerheads and valves.