Gypsy Wells are pits dug right next to a water source (river, lake, stream, pond). In theory, the water will seep into the pit. This is where the sand, clay and rocks will 'filter' the water naturally. It’s not the best answer but it will help rid the water of some toxins. The sand, rock and clay layers between the river and the pit filter out microorganisms (bacteria, fungi and other potentially harmful – itty bitty – toxins). This is ultimately called capillary action where the water seeps through the sand, clay and rocks.
To dig a Gypsy well and make the water somewhat safer, you’ll need:
A bunch of small to medium rocks
A shovel, spoon, stick or clam shell (never your bare hands, too many leftover fishing hooks and broken glass shards).
A small fire
Tongs are helpful but not likely in a true survival situation. (You'll see why here in a minute.)
Find a shallow place next to your water source. You want gravity to do the heavy lifting so if you can find a place where your water will filter in slightly lower than the water source, that's even better. Aim for about 6 inches away from the water source if at all possible.
Start a small fire somewhere close to your dig spot.
Once the fire is going, add your rocks. Let them get as hot as you can. This usually takes about 30 minutes depending on the size of the rocks.
Take the shovel, stick, spoon, clam shell (whatever you have) and dig downward next to your water source about 6 to 8 inches.
Before you're done digging into the pit, the water will start to seep through. If you're absolutely desperate, this may be enough to filter out the majority of toxins but I wouldn't drink it just yet. The water has only passed through one filter.
Grab your tongs or multiple sticks and take the rocks out of the fire and put them into your gypsy well. (This is why you need them. The rocks will be too hot to touch even with cloth, like the edge of your shirt, for example.)
If the rocks are hot enough, the water will start to boil (yes, boil). Once the rocks reach about 212 degrees internally, it takes 5 to 7 minutes to 'cool' them in the water. During that process, the water will reach 212 degrees and boil the water. 5 to 7 minutes should be enough time to kill off any lingering bacteria.
The water should be just clean / filtered / bacteria-free enough to drink.
In theory, this is how it should work. Your results will vary but don't give up if it doesn't work out the first time you try to dig a gypsy well. This takes practice and, well, to be brutally honest, enough guts to actually drink the water. I don't know how else to say this but that city water you're currently chugging probably has as many toxins and or worse impurities in government issued doses.
Desperate times. . . you know the rest. So, if you're stuck somewhere, consider digging a small gypsy well when you need emergency water.