The yard can offer hints: lids in the lawn, a green patch, a capped pipe. They prove little, and nothing about them is a reason to dig or open anything. A deed or an old closing file may also say, and the seller of a house you are buying should be asked directly.
Does living in a sewered town mean you are on sewer?
Not by itself. The Ocean County Utilities Authority lists thirty-three municipalities and three plants (archived copy), and its customer list includes Barnegat, Berkeley's sewerage authority, Brick's utility, Lacey's, Stafford, Long Beach Township and Toms River's. One of those plants, the Central plant in Bayville, is a 32-million-gallon-a-day plant commissioned in 1978, according to a 2023 congressional letter. A town on that list can still have streets or single lots on septic, so the list cannot answer the question for your house.
Why does it matter which you have?
Almost everything downstream changes. A septic house has an inspection and pumping schedule and a state rule that makes the owner report trouble. A sewer house has a lateral that can carry a backup home, and a backwater valve is for that house only. At a sale, an old cesspool brings its own rule. Treat any lid you find as closed for good. Gases in a tank or pit can kill, and only licensed people should open one.
Also asked
What if neither the bill nor the file gives an answer?
Ask your town's sewer department or utility whether the address is connected. If the records run out, a licensed plumber can trace where the house line goes without anyone opening a tank.
Could a house be on sewer with an old tank still in the yard?
It could, and paper may not mention it. Ask the board of health what it knows about the old system, and keep off any cover you cannot identify.