During the Middle Ages people preferred beer over water due to the scarcity of clean drinking water.
Brewing process makes beer cleaner than its original water source and since the purity of water could seldom be guaranteed in the Middle Ages, alcoholic drinks, especially beer, were a popular choice, having been boiled as part of the brewing process.
Beer was one of the most common drinks during the Middle Ages. It was consumed daily by all social classes in the northern and eastern parts of Europe where grape cultivation was difficult or impossible. Though wine of varying qualities was the most common drink in the south, beer was still popular among the lower classes. In England and the Low Countries, the per capita consumption was 275-300 liters (60-66 gallons) a year by the Late Middle Ages, and beer was drunk with every meal.