The domestic wastewater and the heavily polluted rainwater from the street are collected in a common canal. From there it is directed to the sewage treatment plant.

The rainwater from the roof is led through rain gutters into infiltration shafts or infiltration troughs and infiltrated there. The rainwater can also be stored in a rain barrel for the irrigation of plants.

• Lower investment and maintenance costs than separation system (one channel only)
• Higher purification efficiency of the wastewater treatment plant due to more uniform inflow
• Clean rainwater is used for irrigation of plants or groundwater recharge
• Measure against heat island

• Maintenance (sewer and on-site systems)
• Greater space requirement for infiltration areas