If you live in Pennsylvania, own a private well and you want to have the water tested before a gas company is going to drill in your area,
this is what you do:
Go to this page and select a commercial laboratory in your area because they’ll have to come to your house to take a sample:
Look for a laboratory with the following codes:
M = Microbiology
TM = Trace Metals
NM = Inorganic Non-Metals
Contact the laboratory and order a water test for predrill parameters.
This is a list with the parameters as targeted by the Department of Environmental Protection bureau (DEP):

But this list is not completely up to date.
These parameters have been used historically by the Bureau of Oil and Gas but it has come to light that the Dissolved residue (4th parameter) and the labs have been told by the DEP not to run this test any longer.
A commercial water testing lab will have a list of all required parameters as well.
The lab we chose has also began to analyze for Arsenic because it is documented in earlier testing from the PA cooperative extension to be in Gas well Flowback.
We chose Seewald Laboratory.
More information about water testing and drilling:
http://water.cas.psu.edu/ws_testing.htm
The cost for this test at Seewald is $320 plus a sample fee of $35.