The advice of the Prophet about drinking water can be summarized as follows:
It is sunnah to say bismillah while drinking water.
The Messenger of Allah states the following: “When you drink water, say Bismillah; when finish drinking water, say Alhamdulillah.” It is also sunnah to drink water in two or three breaths and by sitting. (Tirmidhi, Ashriba, 13)
However, it is also narrated that the Prophet drank water while standing though very rarely. (see Bukhari, Hajj 76, Ashriba 76; Muslim, Ashriba 117-119)
It aims to show that it is permissible to drink while standing and that it is not a sin.
According to medical authorities, the water that is drunk in two or three breaths by sitting enables the absorption of the water required for the salivary glands, as it remains more in the area of the tongue and mouth. This increases the secretion of saliva, which has an antibacterial and antioxidant effect. Consequently, the mouth, teeth, stomach and intestines become healthier.
The Prophet (pbuh) warns his ummah about not drinking water in one breath as follows:
“Do not drink water in one breath like camels. Drink in two or three breaths. When you drink something, say Bismillah; then, say Alhamdulillah.” (Tirmidhi, Ashriba, 13)
It is stated by specialists that drinking water in one breath risks the heart in cases when the heart beats fast and shrinks by stimulating the stomach and intestines and causing pains.
The Prophet (pbuh) states the following in another hadith:
"Do not drink water as if you are filling water from a tank like a child sucking milk; liver diseases will occur if you do so." (Bukhari, Ashriba, 26)
Scientific studies state that the organ responsible for thirst is the liver.
According to medical authorities, it is a scientific miracle of the sunnah of the Prophet that he recommended drinking water in three breaths, not in one breath. According to the findings, when water is drunk in one breath, the water that suddenly descends affects the liver adversely and causes the fibers to harden and to spoil. When water is drunk slowly in three breaths, the liver is stimulated in the first sip and becomes ready to meet the water. In the second sip, the water is gently welcomed. In the third sip, the water enters the liver softly and easily.
It is known that the interest in the hadiths and practices of the Prophet about health has increased in the western world of medicine in the last thirty years. The reason for is the fact that the advice and practices of the Prophet call Tibb an-Nabawi (Prophetic Medicine) have been accepted by modern medicine.
The Quran states that the Prophet does not say anything on his own and that what he says is nothing but revelation. (an-Najm, 3)
There is no wrong knowledge in the Sunnah, which is the second source of the religion since it is based on hidden revelation and inspiration and it is under divine control. If what he said at the time when there was no microscope and when microbes were unknown could only be known through microscope and analyses today, it means it is a scientific miracle of the Prophet that is known today and it confirms his prophethood.
If there is a hadith and sunnah contrary to reason and science, it means there is a problem. It is either related to the origin or soundness of the hadith, or the reality of science because there is no problem in sound hadiths. Besides, today’s science supports the health of sound hadiths.