A self contained battery operated pump assembly to be installed in fluid communication between a shower arm and a shower head includes a pump; a pump motor connected with the pump for, when energized, driving the pump; and a battery that is electrically connected with the pump motor for energizing the pump motor. An inlet fitting is in fluid communication with the pump for directing water from the shower arm to the pump, the inlet fitting being configured for connection with the shower arm. An outlet fitting is in fluid communication with the pump for directing water under pressure from the pump to the shower head, the outlet fitting being configured for connection with the shower head.