A gurgle is normal when the system is producing water and sending concentrate to the drain. It's just water flowing through the drain saddle into your pipe.
But, listen for the pattern:
- Normal: Intermittent gurgling only when the system is actively filtering (tank refilling).
- Problem: Constant gurgling or sucking air sounds. This often means the drain line isn't secured properly or the drain saddle is leaking air.
To fix a problematic gurgle: Check the 1/4" black drain tube connection at the drain saddle. Make sure it's pushed all the way in and the saddle clamp is tight on the drain pipe. The saddle should be installed vertically on a straight section of pipe, not on a bend or horizontal run.
If that didn't work: The drain saddle itself might be cracked or the needle valve inside might be loose. Inspect it.
Heads up: The drain line must have an air gap (via the air-gap faucet or a separate device) as required by your local code to prevent contaminated drain water from back-siphoning into your RO unit.