Annual wastewater disposal tax not in line with the principle of causality

Facts

The heirs [A.] are co-owners of a two-unit villa connected to the municipal wastewater disposal network of the municipality of Y. The municipality invoiced the heirs [A.] an annual wastewater disposal tax calculated on the basis of the fire insurance value of the building. The heirs [A.] contested this tax on the grounds that it does not take into account the actual water consumption. The Administrative Court dismissed the appeal, considering that the maintenance costs of the disposal network are independent of the volume of wastewater. The heirs [A.] then appealed to the Federal Tribunal.

Considerations

The Federal Tribunal upheld the appeal. It considered that the annual wastewater disposal tax, which completely disregards the volume of wastewater, violates the principle of equivalence derived from Art. 8 and 9 of the Federal Constitution. Indeed, the value of the service must be proportionate to the economic benefit received by the beneficiary, which is linked to the quantity of wastewater discharged into the facilities.

Furthermore, Art. 3a and 60a of the Water Protection Act contain an incentive element that requires taking into account in the calculation of periodic wastewater disposal fees parameters related to the actual use of…