We're talking about the water equivalent of having the feed to your house that first goes through an open rain barrel at the front of your house, something anyone passing by could lob cigarette butts or other garbage into.

You'd ask the water company "can't I provide my own connection to the water" and they'd say "No". Then you'd want another water company, but no such company exists because they're a monopoly.

At that point you'd be better off collecting water from your roof and filtering it yourself. The water company is not helping.