The apparatus and related method employ fluid pressure to first separate the water accumulation chamber from the filtration chamber of a filter assembly by closing fluid flow pathways that allow water to flow into the accumulation chamber. With the chambers separated, fluid pressure is applied to the accumulation chamber to open a drain valve and push water out of the accumulation chamber. The period for which pressure is applied to the accumulation chamber can be regulated by sensors detecting a low water level, or can be timed, or both. When the water removal is completed, the fluid pressure is removed and fluid communication between the filtration chamber and the water accumulation chamber is restored.