Is Tap Water Safe for Houseplants? City Water? 

For the most part, tap water is safe for houseplants. The three things that people are afraid of in tapwater is chlorine, fluoride, and chloramine. There’s things you can do to make tapwater more safe for house plants. You can let your tapwater sit out for 24 hours for the chlorine to completely gas off. Allowing the water to sit for 24 hours will completely remove all the chlorine.
Fluoride is a common chemical that some house plants do not appreciate. For example, spider plants do not like fluoride in the tips of the leaves will turn brown. Those two chemicals are the ones who mainly have to concern about.
If you’re worried about using tapwater on your house plants you could also consider using rainwater. There are tons of different ways to catch rainwater when it rains from the sky. You could use a large drum and put it at the end of your gutter system which will fill when it rains. Rainwater is the single-handed best option to water house plants with.