"People think there must be something wrong with tap water because it is so cheap and plentiful." However,
from the perspective of safety, tap water may be a better choice for you and your family (Business Insider, 2013).
Safety Tests
Tap water must be checked daily under a rigorous inspection regime. However, bottled water manufacturers are only required to undertake monthly test.
Disinfecting Additives
Tap water usually contains a little chorine to disinfect harmful contaminants to ensure water quality, in contrast, bottled water usually does not contain such disinfecting additive once been sealed.
Because of poor safety tests and lack of disinfecting additive, bottled water seems to be more dangerous than what comes from tap.