all those named water contains contaminants. the only way to know of the degree of them in the water is to know the ppm (parts per million). there is a simple unit called a tds testers. i bought a water purification unit from a site http://www.321global.com
2 months ago. it gave me the best tasting water i have ever tasted. all pure. the system was easy to use with my faucet water and i was able to test before and after. hope i was of help to you