Abstract: A water filter arrangement (10) for trapping gross pollutants flowing in a storm water system is provided in-line or at end-of-line of a storm water pipe. The arrangement comprises an inlet (14) and an inlet area (18) which directs incoming water (16) into a filter (20). The filter traps entrained gross pollutants and filtered water exits the filter via filter outlet (50). The outlet (50) and surrounding walls (58 and 57) are shaped to create a flow of filtered water which forms a water barrier which restrains the flow of water and gross pollutants from the inlet (14) to the outlet (52). The water barrier is located between the inlet (14) and the outlet (52) preferably closer to the outlet than the inlet. As the filter (20) becomes full and the flow of filtered water exiting the filter decreases the water barrier subsides.