If your septic system is a holding tank and a dispersion field, I would make sure that what you have can handle the volume that you are going to introduce. It's not just the liquids that have to be dealt with. These systems are designed to deal with a flush at a time. Is there a pump or is it gravity......?
If you are connecting to a municipal sewer system, you should have no problems. You probably have a
4" PVC pipe with gravity flow to the main in the street. Find the end of the pipe and install a cleanout if you plan to extend it later. Make sure the pipe is capped upstream of the cleanout. If not, just install a 4" sweep (not an elbow) and extend it to the surface. Find an adaptor like you would see on an RV site and make sure it has a screw adaptor on top. Just hook up like you do at a camping site.
Ask your local RV site who their suppliers are........
The link below shows a typical arrangement from google. Or Google it yourself if the link scares you.
https://www.google.ca/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwir3L7zs6PVAhUOzGMKHaSyAdYQjRwIBw&url=http%3A%2F%2Fwww.mountainview.gov%2Fdepts%2Fpw%2Ffaq.asp&psig=AFQjCNHLCs9jHMMd567emXkZjjBdnlB2fg&ust=1501036666987513