Review on 2-Pack Quickun PVDF Plastic Inline Check Valves With 3/8" Barb Hose Fitting For Non-Return Flow Control In Fuel, Oil, Water, And Gas Pump Systems by John Souza

As a check valve these work great. However, for a gravity fed water application keep a water at a certain level from a float valve and to just prevent back flow these won't work well. The water has to be much higher on the supply side to get the valve to open. The height differential needed to open the valve is not always consistent. Therefore, you cant get consistent reliable results. I don't redcomend trying to use it for this type of application.