Next to air, water is the most familiar substance on the earth and an adequate supply of water is essential to life. Whereas, the cycling of water serves to replenish our supply of fresh water, the importance of unpolluted and clean drinking water can not be underestimated as we could live without food for nearly a month but without water we would last only a few days. Accordingly getting a dependable supply of fresh water has long been both a necessity and a problem, the gravity of which may be realized from the well known case-history of Prophet Moses and his own people, the Israelites.

When Moses led the Israelites out of Egypt into the wilderness, he encountered a large dessert area where potable water was scarce.  While very many people know the Biblical and Qur'anic accounts of how Moses was commanded by Allah to strike a rock with his miraculous Asa (stick) for getting water to quench the thirst of his people, a peculiar incident at a place namely Marah, is less known. At Marah water was available but it was not potable due to its bitterness and slippery nature. Since the Israelites could not drink this water, they again made Moses pray Allah to make water potable for them. According to the accounts in Exodus, when Moses yielded to their request, he was commanded by Allah to get thrown a particular dried log of a dead tree into the said water body. When Moses made his people follow Allah's command, the bitterness of water vanished soon and water became potable.

This particular incident may be taken as yet another miracle of Moses. Whatever, the actual and factual case might be from the religious point of view, the happenings at Marah may be analyzed from the chemical point of view and a plausible explanation might be given to purification process of water. The water at Marah, a dessert place, was probably alkaline and hence bitter and slippery in nature, the two important properties of an alkaline solution. In fact waters of dessert areas become alkaline as a result of solubilisation of salts of alkali and alkaline earth metals due to percolation of rain waters. Later on the waters, having these hydroxides, are concentration due to evaporation.

The said log was probably a large part of an old dead tree and had been bleached by the scorching heat of the sun in the dessert. Such bleaching could have oxidized the alcoholic groups in cellulose to carboxylic acidic groups and these acidic carboxylic groups served to neutralize the basic hydroxyl groups of alkaline water. Whereas it is simple acid-base chemistry which students, even at foundation level can understand today, at that time it was certainly not less than a miracle when people had no idea of science and technology. Nevertheless, not only chemistry connections were there but also Moses was commanded by none less than the Almighty to make use of both the chemistry connections and the available Technology at that moment for benefit of his people.