FWIW this depends on the religion, traditional Christian fasts usually did allow water even in their strictest forms https://en.wikipedia.org/wiki/Black_Fast ht

FWIW this depends on the religion, traditional Christian fasts usually did allow water even in their strictest forms https://en.wikipedia.org/wiki/Black_Fast https://en.wikipedia.org/wiki/Black_Fast Although as others pointed out, Ramadan in Islam does not.