My water lines were blowing air along with water at the faucet. The toilet tank (not the bowl) would bubble after the float valve in the tank shut off the water. The water volume was fine it just would blow air along with the water. I shut off the pump and drained the storage tank. The tank expelled the water along with the gushing air. I then took an air pressure reading of the storage tank. The air gauge did not move - 0 PSI. I replaced the storage tank. As I am waiting for the glue to cure (the directions specify letting the glue set for at least 2 hours before putting the system under pressure) I can hear the water line coming in from the well gurgling. The well pump is approximately 15 years old and I am wondering if the check valve in the submersible pump is going bad. I have a check valve at the beginning of the T for the storage tank (submersible pump, well pipe, check valve, T, storage tank). The well is over 350 feet deep (pump at 325 feet) and I just checked the water volume in the pipe. The static pressure has water in the well casing 60 feet down. What are your thoughts? Thanks in advance for any and all comments.