I just installed my first RO unit. Installation went without a hitch but my question is that this unit seem very loud, meaning I can hear water running in the adjoining room. It is not leaking, the sound is coming from the black line at the rear of RO filter that goes up to the faucet. I figured the sound right after the install would be attributed to the filling of the system possible air in system but 3 days later I still hear it. No this sound is not continous it seem only while the unit is refilling. The manual says it is normal to hear water running in the drain but this is definately coming from the drain. Any ideas apprecited.