The highly spiced, meaty dishes at a feast made diners thirsty. What did they drink? First, what didn’t they drink?
Water.
Water was universally shunned as a beverage, for a number of reasons. First, cold water was considered unhealthy by medical food rules: it put out the fire in the stomach. Second, it was bland and plain, which was unfashionable. Third, it was often contaminated.
Europe’s water supply came from thousands of springs and streams, which were presumably clean in the days of the Celts, Romans and early Franks. By the High Middle Ages, most people’s water supply had been compromised. In the country, most water came from dug wells, into which dirt and rain fell (and sometimes bodies fell in). Country water also came directly from rivers and streams. There was no way of knowing whether someone upstream had used that same creek or river to wash out chamber pots, or worse. Country people put human waste directly into rivers and creeks without a second thought.
Cities were usually built around rivers that had tributary streams. As the cities grew, many of these streams were built into tunnels under the streets. Other streams were left exposed, but the businesses that located along them were water-using businesses. Many used the water to wash out butchering blood or the scraped waste from tanning. Cities also typically provided public lavatories by building stalls along the river bank. By the late Middle Ages, the rivers in major cities smelled terribly of raw sewage, especially on a hot summer day. They began dredging and cleaning them, but it was long past too late for drinking water quality. Water might be piped in from outside springs, and water-sellers brought it in casks on carts, but in major cities, clean water was always in short supply.
Monasteries were the most likely to have clean water, and monks were among the few who drank plain water with their meals. Monastic compounds were usually located near towns but in the country; the monks put a lot of thought and work into planning their facilities. A really well-done monastery piped in water, with hollow logs and metal pipe sections, from some spring a mile off. The water came into the compound and went to fountains and then into kitchens. Down the line, as slops were added, it went only for laundry and industrial use. Along the way, the channeled water ran straight through the outhouses, flushing the waste out. At the end, the waste water had to go somewhere: the ideal place was the fish pond, where some natural sewage-treatment happened. Non-ideal places included the public river or a neighbor’s field.
Cooking always meant boiling the water, so cooking with contaminated water didn’t concern them. Ale, too, required boiling the original source water. It seems likely that they had learned in a pragmatic way that boiled water is safer, but without microbe theory, they never actually did much with the idea. Coffee and tea hadn’t been imported from the east yet, so boiled water couldn’t be flavored in interesting ways. Water came to the feast table, but only to pour over hands: never to drink, at any temperature.