There are two drain systems.
Sanitize sewer and storm drain.
Sanitize sewer connects to city sewer treament plant.
Storm drain directly connect to rivers.
Sanitize sewer connects to city sewer treament plant.
Storm drain directly connect to rivers.
Your toilet connect to sanitize sewer, which should not back up during storm.
sub pump can be connected to storm drain system, but most old home basement does't have storm drain connection.
sub pump can be connected to storm drain system, but most old home basement does't have storm drain connection.
