im not sure i have not tested it, however you can actually check the water quality online. the website is:
http://www.epcor.ca/pages/water/Wate...y/wqdaily.html
other than that, i have no idea. I use only supermarket water for my tanks. the big jugs that you have to fill up yourself. it is filtered 4 different ways. carbon filter, RO,UV, and sediment filter. it is probably some of the purest water you can get. and it is less than 5.00 for 18L of water.