Case 1 is recorded if the sewage disposal system is connected to the sewage network.
Case 2 is recorded if the sewage disposal system is a sink or other system.
Sewage in a sink is when the sink is located away from the toilet but is connected to it by a pipe or it is directly underneath of the toilet (like in some agricultural areas).
In this case, sewage directly to the sea or river is included.
If the sewage does not end to a sink or sewage network or river or sea then case 3 is recorded.