You need to know the contaminate to properly filter.
NJ well testing act has driven up the cost of testing(for a real estate transfer), which used to be free from the local county, to about $1000. However, you don't need certified testing at this point, and a re-test for a single item is much cheaper.
I would test for your concern contaminate, you may not have a problem. In any event, I wouldn't use the company in Flanders, with the fancy web site...... Your town or county may have resources for local homeowners.
We happened to grow up in this neighborhood, moved out in the late 70's, found out later that our well was probably contaminated with carbon tetrachloride by a neighbor.
https://www.nj.gov/dep/srp/community/sites/pi/g000011456.htm
In the case above, the contamination travelled about a half mile.