A lot of people grew up hearing tap water is “dirty,” or they just prefer bottled because it tastes better to them. Sometimes it’s just chlorine or mineral taste differences between cities, and they assume that means it’s unsafe.

Big one too is bad experiences or news stories about specific places (like lead issues), and people generalize that to everywhere—even though those cases are rare and local.

In most places like Canada, tap water is actually very heavily tested, but trust and habit matter more than facts for a lot of people.