Commentaries: Art. 44

Drainage water from underground buildings must be contained and channelled off in such a way that it cannot be polluted by such construction operations, in particular by exceptional events. This does not apply to small amounts of drainage water if retention measures prevent the pollution of the receiving waters.
For the discharge of drainage water from underground buildings into watercourses, the following applies:
1. the spillway construction must be such as to ensure homogeneous and rapid mixing of the water;
2. the temperature of the receiving waters must not be raised over its near as possible natural state by more than 3 °C; if the stretch belongs to a trout zone, the temperature must not be raised by more than 1.5 °C;
3. the discharge must not result in the water temperature exceeding 25 °C.
Depending on local circumstances the authorities shall specify:
1. requirements for discharge into lakes and infiltration;
2. additional requirements for discharge into watercourses if necessary.