My aunt and uncle have both well water and city water. They have a switch so that they can switch the source back and forth. The idea is that they will have "well water" in an emergency when they don't have city water (they also have a electric generator).
BUT they only use well water, the city water is the back-up. They only switched to city water for a few months when there was a drought and they couldn't get much water from their well.
So that might be an idea for you - have both "available" with a switch and then just don't use the city water??