A compact water filter includes a housing, a filter and a water pump. The housing includes a bottom container and a pump casing. The bottom container has a top cavity and a water inlet communicating with the top cavity. The pump casing is mounted on the bottom container to cover the top cavity and has a water discharge port. The filter is mounted and held in the top cavity of the bottom container to remove contaminants from incoming water. The water pump is mounted in the housing to pump water into and out of the water filter through the water inlet and the water discharge port. Consequently, the water filter holds most of the pool water in the bottom container to lower the center of gravity of the water filter to keep the water filter from overturning when the water filter is operating.