مسائل المنتخبه (Articles Of Islamic Acts) - الخوئي، السيد أبوالقاسم - الصفحة ٣٤٢ - THINGS WHICH MAKE A FAST VOID

VI. IMMERSING ONES HEAD IN WATER
١٦١٧. If a person observing fast intentionally immerses his entire head in the water, his fast becomes void even though some part of his body may remain out ofwater. On the other hand if his entire body is in water but a part or his head remains outside the water his fast does not become void.
١٦١٨. If a person immerses half of his head in the water once, and the other half the second time, his fast does not nullify.
١٦١٩. If a person goes down into the water with the intention of immersing his entire head and doubts whether or not his entire head went under the water, his fastbecomes void, but he need not make atonement for it.
١٦٢٠. If the entire head goes under the water, the fast becomes void, though some hair may remain out of water.
١٦٢١. There is no harm in immersing ones head in liquids other than water (e.g. in milk). Rather what is more apparent is that immersing ones head in mixed water does notalso invalidate ones fast, though precaution lies in avoiding it.
١٦٢٢. If a person observing fast falls into the water involuntarily, and his entire head goes into the water, or if he forgets that he is fasting and immerses hishead in the water, his fast does not become void.
١٦٢٣. If a person throws himself into the water thinking that his entire head will not go down into the water, and water covers his entire head, his fast remains inorder.
١٦٢٤. If a person forgets that he is fasting, and immerses his head in the water, or another person makes his head go down into the water by force, and herecollects under the water that he is fasting or the other person releases him, he should take his head out of water at once, and if he dog not do so, his fast becomes void.
١٦٢٥. If a person forgets that he is fasting and immerses his head in the water with the intention of taking bath, both his fast and bath are in order.