Find a local Environmental Testing Lab. One I use here in Arizona is Legend Technical Services but there are labs all over. If you look here: http://www.legend-group.com/services/homeowners/privatewells You will find some examples of different domestic well analysis packages along with a list of other contaminants that can be added. I would explain to the lab your concerns about the previous owners practices and have them suggest a package to suit your needs. Your concern is very real. Back whn I managed a Municipal water utility, we discovered an illegal auto scrap operation in a remote riverbed which flowed in to our jurisdiction. They were stripping cars then had a huge grinding or recycling machine that chewed cars up into what they call "fluff" or shards or scrap and abandoning it on site then moving on. The problem was they were not removing things like batteries, brake lines, fuel tanks and such and that was all leaching into the water table. It became a Superfund clean up site very quickly and we were able to contain it fortunately but it was a major undertaking.