Water running continuously nonstop drain when tank is full:

The drain should stop when the tank is full and you're not using water.

If the water keeps draining, then there are 2 possibilities:

1. the auto-shut-off valve is not functioning correctly, need to replace the valve. This is the device that has 4 tubing connected to it. It looks like a square block or disc shape

2. the check valve is not working correctly.

Both are wearable parts that need to be changed every 2 to 3 years along with the membrane flow restrictor.

Here's the part you need: RO Maintenance Kit Please make sure to select the corresponding maintenance kit for your RO system model. Any questions please feel free to email us.