Diagnosis
That’s usually water hammer or high pressure causing the solenoid valve inside the faucet to vibrate rapidly. It’s annoying but often not a sign of immediate failure.
How to Fix It
First, try the simple fix: turn on the faucet all the way. If you only open it part-way, the water rushing past the valve can cause that chatter. Always open it fully. If it still chatters at full open, the issue might be your household water pressure. You can install a small water hammer arrestor on the cold water supply line feeding the RO system. For the RCC7AK, it’s sometimes recommended to add one if your static pressure is above 80 PSI.
If That Didn't Work
The solenoid valve in the faucet itself might be failing or have debris in it. You can try disassembling the faucet head (usually by unscrewing the aerator) and flushing it out. If the noise persists, the faucet may need to be replaced.
Heads Up
Don’t ignore super high feed pressure. The system’s max is 100 PSI. Sustained pressure above that can damage the ASO valve and membranes. Consider a pressure regulator if your house pressure is consistently high.