Reference: Fataawa Ramadhaan v2 p537 no.511
Majmoo’ Fataawa Ibn Baaz v3 p252
Question: A man who was fasting took a bath and due to the force of the pressure of the water, water entered [his mouth and then] his stomach without him intending; So is he obliged to make up [the fast for that day]?
Response: He is not obliged to make up [the fast] since he did not intend [to take in water], so his ruling is [similar to] that of the one who was forced [into doing that which rendered the fast invalid] and one who had forgetfully [done that which rendered the fast invalid].
