Is the fast valid if I intended to fast, then woke up and drank water, then realized it was 5:30?

If a fasting person eats or drinks, thinking that night still remains, and then it becomes clear that dawn has broken, there is a difference of opinion among scholars regarding the validity of their fast. The opinion that the fast is valid in this case is strong, even though the majority hold a differing view. If the fast was a voluntary one, then reward is hoped for. If it was an obligatory fast, then it is more cautious to repeat it to avoid the difference of opinion.