Using a Bidet while Fasting

Q: Would water from a bidet break the fast?

A: The ruling returns to a broader principle: if a person deliberately causes something to enter his internal cavity (al-jawf), or any hollow space within the body, the fast is invalidated. This includes entry into areas such as the brain, the throat, or the internal cavity of the anus.

Accordingly, if water from a bidet remains external and is limited to washing the outer area, the fast is not invalidated. External cleansing has no effect on the fast.

However, if water is deliberately introduced such that it enters the anus and reaches the internal cavity, the fast is invalidated. This falls under the same ruling as inserting a substance into the body, whether by enema or otherwise. An unusual route is treated like a usual one when something reaches a hollow space within the body.

Likewise, deliberate insertion of a finger or similar object into a bodily cavity that is considered internal carries the same ruling.

If entry is not deliberate, and one is merely doubtful whether anything reached the interior, the fast is not invalidated by doubt alone. Certainty is not removed by uncertainty.

Source: Kashshaf al-Qina