Word just in...there are 2 wells...one for irrigation and one for potable use. They do not test the irrigation well. There is also a storm water catch basin in close proximity to the potable supply well...not a very good idea. The riser used to be flush with grade but was extended about 5 years ago.
Again, at this point I'm just going to flag the irrigation system as a potential source and let them follow up on it. It's not something that occurred to them. I'm sure as hell not going to get an attorney either. But yes, they should test nearby wells too. The problem with bacterial contamination is that it's not as easy to backtrack to a source area as other sources of contamination. For something like gasoline or solvents, you get a distinct plume that fans outward from the source and reduces in concentration with distance. Bacteria are living things that can multiply by themselves, so the concentration detected may have little correlation to proximity to the souce area.