Tap water debate turned our plant meetup tense last weekend

At our monthly plant swap, two members got into a heated discussion over watering philodendrons. One argued that tap water is perfectly safe and saves money, while the other claimed filtered water is essential to avoid leaf spots. It got awkward when others started picking sides, and now there's a bit of a split in the group. What's your take on using tap vs. filtered water for houseplants?