What to do when you well is contaminated? It depends on what is it that is contaminating it and what is it's source.  Wells can be contaminated with bacteria, hameful chemicals, and just to much normal elements that exceed the EPA standard.
Bacteria can be in a well if the well is broken or cracked.  It can also be an issue if the well has been left for a long period of time without being used.  To remediate the situation you can repair the well if need be or replace the well, it could be just bleaching may be enough to eliminate the bacteria.

Sometimes the ground water becomes comtaminated with nitriates that exceed the EPA safe standards.  This could happen near a golf course or agricultural area.  Some areas remediate this situation by bring in Public water and sewer.  It might be possible to put in a deeper well.  How deep? You would have to consult the Leelanau and Benzie Enviromental Heath Dept for a permit.  I have known this to happen and homeowners have had to go 250ft deep.  There is no one answer or one size fits all senerio, as the location and availability of public sytems will determine what is necessary.

A private well can be contaminated by your own private septic drain field!  Yes, care needs to be take to location of the well and spetic, the further away from each other the better.  Wells that are too shallow might be found to be contaminated 30 years down the road.  Take care and have your well water tested often.

Harmful chemicals require more and different types of test to detect.  Beware of the location of the property and what might be near by.  Commerical buildings that are near buy know what kind of business they do and how they dispose of chemical if any.  Hopefully you understand the
potential for soil contamination near a gas station or land fill.  Reguations are set up to prevent
contamination for places like this but those regulations have not been in effect forever.  There are those that break rules too.   Knowledge is key, and a trip to the Benzie and Leelanu Health Dept can be enlightning.
Real Estate agents can be a good source of knowledge especially for out of town buyers.  Getting you answers and leading you to the resources you need to make an educated decision is what they do. For Help visit http://www.LeelanauandBenzierealestate.com for your Sleepin Bear Dunes Specialist!