2. Interception ditches are generally set at the entrance of the basement, and the rainwater and sewage flowing into the interception ditches are led to the collecting wells.
3. The residual water in the domestic water tank and water pump, or in the process of equipment maintenance, is also led to the collecting well.
4. In case of fire, the fire water of automatic sprinkler system or fire hydrant should also be led to the collecting well.