Tap water (wikipedia.org)
Drinking water (wikipedia.org)
Safe tap water (onedrop.org) 
Tap water drinking in other countries? (worldtrips.com)
Countries where you can't drink tap water (dailymail.co)
Best tap water in the world (wetapwater.com)
Best quality tap water (greentumble.com)
Ways to clean tap water (wikihow.com)
Emergency Disinfection of Drinking Water (epa.gov)
What's in your Drinking Water? (nrdc.org) 
Top 10 Causes - Outbreaks in Public Water Systems (cdc.gov)