How to open a PVC ball valve with a broken handle, stuck closed?
Ok, you can do one of two things or both. Drill a 3/16&quot; hole into the black valve stem and screw a 1/4&quot; x 1&quot; lag screw into it. When the screw tightens up against the valve stem turn the screw another quarter of a turn and the valve ball could/should open. The valve stops are on the handle and valve housing and since the handle is broken off, the valve ball can be opened by turning it clockwise with the lag bolt. Once pressure is released, you can replace the valve.
Now if that's too much work, just drill a hole in the valve housing where the PVC enters the top of the valve and catch the stream in a bucket. Remember to close the valve feeding the filter and use a cordless drill when drilling into pressurized water pipes. Once pressure's released, replace the valve.