I have backflow preventor attached to all outside faucets for gardening use. This little backflow preventor is made with brass, attached to the faucet at one end, and the garden hose on its other end. I have used them for more than a year and work perfectly. Recently, every time after using, when I shut off the faucet, water splash out from around the backflow preventor, pressure so strong that I got wet all over. Any one know what is wrong with this backflow preventor? and how to fix it?