The automatic shut-off valve (ASO) on the RO head has failed or the storage tank is waterlogged.
Fix:
- Check tank pressure. Empty the tank completely. Use a tire pressure gauge on the tank's air valve. It should read 7-8 psi when empty. If it's zero, use a bicycle pump to inflate it to 7-8 psi.
- If tank pressure is correct, the ASO valve is defective and needs replacement.
If that didn't work: Verify the drain line flow restrictor is installed and not clogged. A missing or faulty flow restrictor prevents proper system pressure from building up to trigger the ASO valve.