It should nevertheless break a fast. I know it's possible to eat very little carbs and still achieve ketosis which is the goal for intermittent fasting but it's better to exclude all carbs while IF.
While coconut water is beneficial during eating windows, it’s not the best drink to have when you fast. Coconut water contains simple carbohydrates, which is why its consumption will break your fast.
https://fulcompany.com/blogs/the-ful-scoop/drinks-for-intermittent-fasting#:~:text=While coconut water is beneficial,consumption will break your fast.