Hooking up anything that allows rainwater into the KUB sewer system can overload the sewer and cause basement backups or sewer overflows.
- Groundwater sump pumps [pumps for laundry water/other household water are okay]
- Foundation drains
- Drains from window wells, outdoor basement stairwells, driveways, etc.
Connecting one roof downspout to your sewer lateral is the equivalent of adding 33 homes to the sewer system. When it rains, the extra water can flood the pipe and cause sewer overflows both outside and inside homes.
Don't connect the examples above. Keep rainwater out of the KUB sewer. Water from driveways, etc., should go into the stormwater sewer, drainage ditches, or soak into the ground naturally.