Does swallowing a water drop by mistake during ablution break the fast? Is the fast of a person invalidated if they swallow a water drop by mistake while performing ablution? Can swallowing water accidentally while performing ablution invalidate the fast? Is the fast broken if a water drop is swallowed mistakenly during ablution? Will swallowing water unintentionally during ablution affect the validity of the fast?
A misunderstanding about invalidating fast is, as in the example of water reaching stomach unintentionally during ablution, that the act invalidating fasting happens unintentionally. Unintentionally performing an act that normally invalidates the fast invalidates the fast, and only qada is required.
If water unintentionally reaches one’s stomach while being forgetful about fasting, fasting is not invalidated because of forgetfulness (al-Fatawa al-Hindiyyah, I, 222). One companion asked Prophet Muhammad (saw), “O Messenger of Allah, I ate and drank in forgetfulness when I was fasting. Is my fast invalidated?” He (saw) replied as, “(No, it is not) Allah had fed you and given you drink.” (Abu Dawud, Sawm 39).
According to the Shafii school, if little amount of water taken to mouth and nose during ablution reaches one’s stomach unintentionally, the fast is not invalidated. However, if water reaches stomach because of an illicit reason such as to cool or play in water or take water to mouth and nose intentionally excessively during ablution and ghusl, fasting is invalidated. Because this means the fasting person did an act that is not commanded to do (Shirbini, Mughni al-Muhtaj, I, 629-630).
Source: Presidency Of Religious Affairs The Turkey, High Board of Religious Affairs FATWAS