I am working through my 30-day due diligence period and it has been discovered that the private well that serves the property contains high arsenic levels at 0.022 mg/L, above the EPA standard of 0.010 mg/L.

My experience is that it's street by street, so dig in deeper in some of those areas and really get to know it.One notable thing to be cognizant of is that there is a super fund (lead and arsenic contamination) in the middle of the city which is not on that map.

That area was the epicenter of the lead/arsenic contamination back in 2017/2018.

The soil engineer can also verify that there are no toxins or contaminants (like lead, arsenic, or cadmium) in the ground.

My question now is what exactly should the well /septic inspection include (bacteria testing, arsenic, e-coli etc)?

Some pump perfect spring water, others pump salt water, hard water, or even worse things like arsenic.

Most places are on well/septic so you'd need to check the soils for arsenic and other contaminants.

Arsenic.

In AZ, arsenic can be a problem and maximum ppms were recently dropped causing private water companies a lot of pain.

Whiting is one of those areas that you need to be a bit careful though, Them and more so East Chicago have had a lot of incidents of lead and arsenic pollution in the soil.https://wgntv.com/2018/05/08/more-lead-contamination-found-in-nw-indiana-soil/