It’s simple : anything other than water breaks a water only fast. The real question is does it matter for what you’re trying to accomplish.
If you’re fasting to cure disease or prevent cancer, for max benefit, drink only water. Look to gurus like Dr Thomas Seyfried or Dr Alan Goldhammer.
If you’re fasting to lose weight or fix metabolic issues, there’s a lot more flexibility. I’ve found that zero and near zero liquids (ie. flavored waters, soda, broth) don’t effect my weight loss. I take chewable vitamins and 2-3 teaspoons of cod liver oil daily, which also has no effect. I haven’t added it up, it’s probably under 200 calories. At any rate, I’ve noticed no difference in weight loss fasting like this versus dry fasting.