This issue is likely due to an airlock phenomenon between the upper and lower tanks. A minimum air gap is required between the two tanks; otherwise, the water will not flow from the tap, and the upper chamber will not be fully filtered.
- The first thing to check if water is present between the two tanks, which can be caused by overfilling the upper tank (even if it was just once!). Be sure to thoroughly dry the bottom rim of the upper tank and the inside of the top of the lower tank, and be cautious during future refills.
- If this does not resolve the issue, you should install the Berkey Stainless Steel Anti-Airlock Clip, which clips onto the edge of the lower tank. The Anti-Airlock Clip will prevent and resolve the insufficient air gap issue. Without an air gap between the two tanks, an airlock phenomenon occurs, disrupting the gravity flow of your system.