The National Drinking Water Database has compiled millions of records from state water officials.
Note: the website seems to have stopped reporting new data after 2009.
Throughout the country, we have found 316 chemicals in tap water.
Once you discover what chemicals are in your local water supply, visit EWG’s online water filter guide to pick a filter that will reduce your exposure to those chemicals.
You might be interested in the site’s Oklahoma’s Drinking Water Quality Report.
The Oklahoma Department of Environmental Quality (DEQ) Water Quality Division may be your best resource if you have additional questions.