I see several suggestions to water your garden with either distilled water, or with water that has been left out for 24 hours to degas. I think it's worth viewing from a skeptical lens.

are plants in general harmed by tap water?

Does anything in the tap water hurt most plants? For a list of chemicals commonly found in tap water, see: [1] [2]

are specific plants harmed by tap water?

There are definitely a few plants that are harmed by tap water. So it's not possible to make the blanket statement that "tap water never hurts plants". However, it may still be possible to make the statement that "tap water doesn't hurt most plants".

symptoms of plant harm