We have had RO system for about 5 years now, and of late I have to open the faucet that is mounted to the counter daily to "vent" off air that is in the water line. I am not sure where the air is entering the system. There are no leaks, assuming pressure on the line would make that obvious. So I at a loss as to where the issue starts. Not familiar with how the RO works, so I am open to any thoughts.