The property disclosure you received when you purchased the home will be able to tell you if you’re on sewer or septic. If you don’t have those documents handy, inspect your property for signs of a septic tank. A septic tank is likely to be visible if you can plainly see a single, unnatural-looking mound very near to your property.
Also consider your home's location. You're probably on a sewage system if you live in town or in nearby suburbs. You're more likely to have a septic system if your house is in a rural region where maintaining a sewer system is likely to be more expensive than septic.
Examine your bills. Because sewer systems are not free, if your home is connected to one, you may expect to get bills from it. If the sewage provider does not charge separately, check your waste or water bill for sewer costs. There will be no cost for your septic tank.