Impressive. If you didn’t know what it was for and you lived in medieval times, what stories would you create around these arches?

Outside of oxygen, water is probably the most necessary ingredient to human life. You can go without food for three weeks or more, though you’ll be weak at the end of it; if you run out of water you’ll die in three to five days, and you’ll be too disabled to survive after two. In hot or arid environments, you can die in less than a day.

Locating sources of safe water has been part of the human condition for our entire history. In a world without tap water, finding water and making it safe to drink often consumed our lives.

Kathy Jesperson, in the Summer 1996 OnTap for the National Drinking Water Clearinghouse, quotes from The Quest for Pure Water: The History of Water Purification from the Earliest Records to the Twentieth Century^• about water treatment from 4,000 years ago:

The Sus’ruta Samhita, Sanskrit writings about medical concerns, dates from approximately 2000 B.C. and offers evidence that water treatment may well be as ancient as humans are. The writings declare that “impure water should be purified by being boiled over a fire, or being heated in the sun, or by dipping a heated iron into it, or it may be purified by filtration through sand and coarse gravel and then allowed to cool.”

As long as you’re going to the trouble to boil your water, you might as well make it more interesting by adding barley or other grains to it. This turns it into a very simple beer. Beer has been part of our daily diet since the time of the Egyptians. From the beginning of recorded history to the Middle Ages, brewing beer was a part of the homemaker’s chores. In the Middle Ages hops were used to keep it fresh during transport. As brewers learned more about hopped beer, beer lasted longer, and a trade in beer became possible.

In A world lit only by fire: the medieval mind and the Renaissance^•, William Manchester^• describes how common beer and wine were:

Every meal was washed down by flagons of wine in Italy and France, and, in Germany or England, ale or beer. “Small beer” was the traditional drink, though, since the crusaders’ return from the East many preferred “spiced beer,” seasoned with cinnamon, resin, gentian, and juniper. Under Henry VII and Henry VIII the per capita allowance¹ was a gallon of beer a day—even for nuns and eight-year-old children. Sir John Fortescu observed that the English “drink no water, unless at certain times upon religious score, or by way of doing penance.”

Today all we need is to turn on the tap, but back then population growth outpaced our ability to acquire clean water.

Abundant water

A sustainable urban civilization is possible only with abundant water. Abundant water is a revolution that makes our great cities possible. And the revolution of abundant water means more than just drinking. Water is uniquely suited for easily cleaning ourselves, for cleaning the things we eat, and for cleaning the things we eat from. I am just old enough to remember weekly baths; I don’t remember being particularly crusty on the sixth day, but I expect that if I met my younger self now, I’d notice it. Just before high school we moved into a new house, and our new house had a shower. I enjoyed it because I no longer had to bathe in grey water if I was the last to use the tub.

As dirty as that sounds today, it was extravagant to people living in the middle ages and earlier. Actually immersing yourself in water to bathe privately in the comfort of your own home required far too much water, and only the very wealthy could afford it. Most immersive bathing happened at public bathhouses—such as the famous Roman baths in the Roman era—or in fresh bodies of water. In each case, bathing was a social event. This often carried over even to those influential few with their own private baths: some showed off their luxury by holding court in their baths.

The dumping of the chamber pot combined with giving extreme insult.

We use water all the time now. We wash after every meal; we brush our teeth at least once a day and are expected to brush three or more times a day. We shave daily, we shower or bathe daily and some of us more than once per day. The kid who used to go a week unbathed without noticing it is long gone; if I go without showering for even two days, I feel it by the end of the second day. We wash our dishes in clean hot water and drink safe cold water whenever we need it. We have private toilets that whisk our crap away through pipes that criss-cross our cities. When our streets get dirty, many cities run water along them to clean them. We have hydrants on every block just in case there’s a fire, to put fires out and to keep fire from spreading throughout our gigantic dense cities. We water our lawns and our houseplants and our gardens and our farms.²

Before the existence of running water, if you lived in a city you pissed in a pot; when the pot filled, you dumped it, hopefully in the cistern out back, but if you were lazy or the local government ran the sewage system poorly, you dumped it in the street. This was often illegal, but eventually most government-run sewage systems failed. Without running water, piss-covered streets were more difficult to clean. If you lived in the country, you might have had an outhouse of some sort. When it filled, you dug another hole and covered the old one with dirt from the new one. You still kept a piss-pot in your bedroom to keep from having to walk outside at night.

Wikipedia doesn’t mention it, but I’m guessing that when you had to go number two in the middle of the night in the middle of winter in Michigan, that piss-pot looked awfully inviting compared to walking outside to the outhouse in subzero temperatures.

By the time I reached high school, outhouses were such a joke we’d steal them for the homecoming bonfire, and nobody got in trouble. There weren’t many remaining; I remember part of the discussion leading up to homecoming was where to find sufficient outhouses. The tradition is probably long gone by now simply for lack of outhouses to steal.

While reliable hot water is a modern innovation, abundant water is not. Imperial Rome had abundant water via their renowned aqueducts, and their fountains and toilets worked pretty much like ours do. Perhaps more than anything else, it was their understanding of aqueducts that allowed Rome to become the great city it was—and the necessity of aqueducts fed into Rome’s growth. Building and maintaining them required organization on a massive scale. After Rome’s fall, the aqueducts failed, and this contributed to Rome’s massive population drop: over a million people at its height, to “as low as 30,000 in the medieval era”. A big city needs water to support its population and Rome without running water could not support a million people.³ Our own grand cities would be impossible without abundant water and the means to distribute it to every home and business.

Finding water

In the typical fantasy medieval world, there is no running water. Water must be brought from wells, rivers, ponds, or some other source daily. If you need hot water, you or your servant must heat it over fire. You may end up planning your life, and especially your travels, around the availability of water.⁴

You drink as much cider, beer, or wine as you drink water. Bathing is a special occasion—you’ll wash your face and hands in precious water, and wipe everything else with a wet cloth if anything. Water is so foreign you probably don’t even know how to swim. You’ll piss in a pot in the night, and a convenient corner in the day. You’ll shit in a hole in the ground. And you won’t have any idea that you even need abundant water, let alone want it. It’s just life in a medieval world.

The most common way of getting water in a world like Highland is to take a bucket to the river, lake, or hand-dug well. Fill the bucket, and drag it back to wherever you need it. If you’re on an adventure, you may not have even that luxury. If you want to survive in a world where water doesn’t come to you, you need to go to the water. If you can’t see water, you’ll need to know where to find hidden water: which plants contain water, which geological formations conceal water, or how to capture the water in the area around you.

The first step to surviving a low-water environment is to stop leeching it from your body. If you’re in the sun, create artificial shade with an umbrella or a hood of some kind, such as a turban. Wear loose clothing and keep it over your entire body—whatever the sun hits will allow water to leave your body.

Eat foods that contain water. Avoid foods with excess salt.⁵ Your body needs salt, and in hot weather you’ll sweat that salt out. But consume excess salt and your body will use your precious water to get it out of your system. Salt water, for example, doesn’t do anything to quench your thirst because the salt content cancels out the water content.

High-water foods

Many fruits and vegetables store water. The citrus family is famous for their juices, but other fruits contain large amounts of water, such as apples, pears, and berries. However, the cost of processing often high-fiber plants can reduce their usefulness as water sources. To improve the water ratio, they can be squeezed in a press to extract the still flavorful liquid before eating them. By their very nature, this liquid is highly nutritious: it is designed by nature to nurture young plants.

Similarly, the females of many domesticated animals produce milk for their young. They can be bred to produce this milk year-round. Because it is designed for newborns, milk is a concentrated food easily processed.

If the liquid can be fermented, it will store longer—the apple is highly regarded as a cider, but the pear also produces fine, usable ciders.

Other plants not known for their ciders can still be pressed for liquid in a pinch. The potato, for example, contains a high liquid content—and a high sugar content which makes it very suitable for fermentation.

Simple presses can be created by carving channels in flat stones. When the fruit or vegetable is pressed into the stone—often by another flat stone—the juice runs out the channels, where it can be collected.

Just about any fruit or vegetable can be turned into water by pressing it. High-water fruits and vegetables include the watermelon, strawberry, grapefruit, cantaloupe, peach, pineapple, raspberries, orange, blackberries, star fruit; cucumber, zucchini, celery, tomato, radish, lettuce, tomato, green cabbage, bell pepper, eggplant, cauliflower, red cabbage, spinach, broccoli.

Some of them will need to be cooked to avoid things like the oxalic acid in star fruit and spinach, but if you cook them, you’ll want some means of capturing the liquid that steams out.

Water-storing foods

In areas where quality water is rare, plants will evolve to store water; you can find such plants in both deserts and jungles. They might store their water in their leaves, in their trunk, or in their roots.

The succulents, such as cacti, agave, aloe, elephant trees, and euphorbias store water in significant enough quantities to quench human thirst.

Finding them is often a matter of cutting into likely plants and seeing what comes out. Be very careful not to eat anything poisonous! Don’t even bother if the plant or its water smells like almonds or peaches. That’s a good bet the plant is poisonous. If it smells reasonable, try rubbing some on your armpit. Wait an hour; if you develop a rash, swelling, or any discomfort, this is not a safe source of water. Finally, touch it to your lips; wait a minute; if there’s no discomfort, touch it to the corner of your mouth; wait a minute; touch it to the tip of your tongue, touch it under your tongue.

If none of that produces any discomfort, try swishing the liquid around in your mouth but do not swallow!

Finally, try drinking (or eating) a small portion of it: chew it, swallow it, and wait five hours.

It should go without saying that eating and drinking unknown liquids should be reserved only for emergencies—but of course, that’s what adventurers are for.

Identifying water under the ground

In a magical world, dowsing, spells, or spirits can be used to identify sources of water.

But more mundane methods will also work even in magical worlds. If you’re near an ocean, digging back beyond the extent of high tide may provide water: water from rain can collect on top of any salt water that seeps in from the ocean.

Another way to find underground sources of waters is to look for plants that require lots of water to grow, such as cottonwoods and willows. If the trees are there, it’s a reasonable bet that the water table is high enough for the tree roots. Mind you, digging a well by hand is hard, dangerous work. For this reason, it is often performed by a community; when wells are on private land they may be considered community property.

When wells or water holes are not community property but are owned, it is likely they will be owned by a tribe or nation. In arid locations where water is rare, wars can be fought over wells and water holes.

Hand-dug wells will have steps or handholds on the side, and often be about four feet diameter. The sides of the well must be lined, with bricks or stones, to keep the well from caving in. Iron rings the diameter of the well, combined with wooden boards, might be used to keep the sides of the well intact until the permanent siding can be installed.

Depending on the technology level, a windmill might be installed on top of the well to assist in pumping the water out.

Because wells are deep, they may also be used for storing foodstuffs that need to be kept cool.

For an interesting variation on the spring-fed well or water hole, you can also build a pond that will capture the water in the air. Dew ponds can condense large enough amounts of water to qualify as a pond: dig a large hole, cover the hole with a thick coating of dry straw. Cover the straw with clay, so that the straw is completely protected by the clay; this is important, as straw must remain dry to insulate the pond against the surrounding ground temperature. Cover the clay with a layer of stones. Over several days, the dew pond will fill with water as dew condenses into it.

In a pinch, if you’re in an area that deposits dew at night, it is possible to collect it without the work of building a dew pond. If you have some absorbent material—cotton works—you can wipe it over grass, boulders, and anything else that collects dew, then squeeze it into your container. In areas with a good dew supply, you should be able to get a gallon of water in an hour with absorbent enough material.

That’s an hour that your character isn’t adventuring, however.

Purifying water

Latrines from the Roman empire.

Water, like just about everything else we eat, goes bad. If you store water for emergency preparedness in the modern world, you probably add eight drops of bleach to each gallon of water to keep the water safe. If you’re into survival, you probably have iodine for adding to unsafe water. Bleach and iodine are modern inventions, so you aren’t likely to have access to them in the medieval world. But you might have distilled alcohol, such as whiskey or vodka. Add a shot or two to your water when you refill your water skin, and while it won’t be as effective as bleach, it will help keep your water fresh. It’s an open question whether and how much it will kill germs and bacteria in water, however.

Given time, you can filter water through sand—or look for water that’s been filtered through sand, such as by digging a hole near a water source such as a jungle river or ocean.

It’s also possible to create a more advanced filter than simply sand. Make a cone of bark or other material, fill it with a small amount of grass and small rocks at the bottom of the cone, sand in the middle of the cone, and charcoal at the top of the cone. Then pour water through the filter several times; this won’t be as reliable as boiling, but it will be better than sand.

Filtering water gets rid of impurities, but it doesn’t kill bacteria. You can also boil water; boiling water won’t filter out impurities, but it will kill harmful bacteria.

And of course neither bleach nor alcohol nor filtering will remove non-living impurities or molecular impurities, such as lead or arsenic!

You can distill water to both filter it and kill everything in it. The basic idea for distillation is to

1. Turn the water into steam.
2. Let the steam condense, either on some sort of roof or in pipes.
3. Collect the condensation, for example by shaping the roof to drip into a container or by collecting the output of the pipes.

Because only the water evaporates, distillation filters out just about everything, even metals and salts. These will remain in whatever vessel was used to boil the water.

When you’re stuck in a dungeon several levels below ground, safe, reliable water may become your most precious treasure!