There are three common places for the leak to occur. The flow rate measurement, the connector assembly to the water tank and the pump assembly.

To identify which of those is leaking, simply look for water where it's not expected. All couplings should be fully dry.

Of the three common places of leaks, most stem from calcification of the connector assembly. Since the standard decalcification methods (with the satches) doesn't touch these parts, it easily gets clogged up and water leaks in between the sealings.

When one of the couplings did fail, or the flow measurement or connector assembly is cracked, replace those parts first