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Clean drinking water: How to develop low cost sources of drinking water just about anywhere (...continued from How to Live Well on Very, Very Little) This page last updated on or about 10-10-06

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A solar still may often produce water even in very dry regions. A small survivalist version of such a still requires a spot getting plenty of sunlight, but also located in a likely area of moist underground regions, like a dryed up stream bed or other low spot in the terrain.

Dig a hole. A depth of one to two feet and outer edge diameter of three feet should do it. Increasing the depth beyond two feet should only help the performance of the device.

Any moist vegetation in the area can be gathered and used to help the still performance, too. If such is available, line your hole with it, compressing it and weighing it down with stones if necessary. Urine and leftovers from meals possibly containing moisture may also be put in the hole for water extraction.

Place a cup or bowl to catch water in the deepest part of the hole (this should also be the center of the depression).

Place a plastic or other waterproof sheet at least four feet by four feet in size over the hole, securely fastening its corners with weights, and somewhat sealing the edges with the dirt removed from the hole.

Now, place a moderate weight or rock atop the middle of the sheet, sufficient to cause a low spot in the sheet directly above the catch container you placed in the hole.

Now the warmth inside the plastic covered hole should cause moisture to evaporate from both the earth and any other contents of the hole, to condense on the underside of the plastic sheet, and run down into the cup.

Such a still will likely only work well for a couple days before a new one elsewhere must be created. Replacing the vegetation or other artificial moisture sources inside the pit will extend its useful lifespan for a while.

Note that the solar still technique can theoretically be scaled up and formalized in structure and materials to become a permanent and significant source for water production and recycling for a family or community. In excessively dry regions, such a still would seem very valuable for purposes of recycling the water in urine and food and crop wastes alone.

Dew or fog collection, or harvesting of water from the air, may be performed on certain nights with the proper traps and drainage. The main trick is to provide cool, smooth water-proof or resistant surfaces for water to condense onto, and direct this water into a suitable storage container. The more surface area your collector surfaces present to moving air, the more water you should collect.

Small survivalist improvisations for dew collection tend to consist of digging a hole, lining it with plastic (or another waterproof layer), and in the bottom depositing lots of small stones or other potentially cool, smooth surfaced objects on which the dew may condense. If enough dew is captured, it will drain to the lowest point in the water proof sheet for collection (be warned that the dew may evaporate away if not collected by early morning).

Tying cloth strips or bundles of thin grass to your ankles and walking through tall grass and brush prior to sunrise may collect some dew moisture, which can then be wrung out into a storage container. Note that this method might be scaled up into a rolling device capable of collecting water from a large brushy area all at once.

Google search: FOGWATER COLLECTION, Fog harvesting, and Drinking Water from the Air may offer more information on this subject.

The pelican tank and pelican-hippo tanks offer a couple of water storage options for remote areas.

On sea coasts, although the ocean water is so salty as to be poisonous, only a few yards from the sea may often be found water sufficiently fresh to collect for further processing via subsequent methods described below.

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The sand dunes or small sandy hills which frequently populate the land just beyond the beach, themselves collect water from rain. Digging a shallow hole behind one of these hills should reveal water. But beware: once the water level is found, keep in mind only the top inch or two will offer fresh water, with the water below that being basically seawater. Fresh water floats atop salt water.

Again, it would seem possible to build a large scale, automated way to collect such water, with a bit of work and thought. Perhaps collectors could detect changes in the saltwater levels by making spot checks of the electrical conductivity of the fluid? When too high a salt level were detected around a certain siphon, that siphon would cease drawing water. When salt levels dropped, the siphon would begin sipping again.

Of course, such a system likely would not provide a continuous or heavy flow of fresh water, being heavily dependent upon local rainfall. And as catching the rainfall directly would be most practical, siphoning the water behind the beachfront hills would at best be a supplementary or contingency method for water collection.

The boiling process described later for purification of water may also be used to produce fresh water from saltwater. Catching and condensing the steam coming off the hot saltwater would provide fresh water. The method could be as low tech as allowing a cloth to saturate in the steam and wringing the fresh water out into a container. This method could also be scaled up and made more automated and efficient. However, it's very energy intensive, and so too costly for long term or heavy use in many circumstances. Bleeding edge low cost methods for desalination via heating today usually exploit solar heat to accomplish the task.

Freezing too can be used to desalinate water, but it suffers high cost liabilities as well, with most of the methods commonly available today. Bleeding edge low cost methods for desalination via freezing today usually exploit the natural freezing temperatures of winter to divert or isolate a substantial quantity of sea water into a spot where it will conveniently freeze and be further processed and then stored away as drinking water. However, using this method requires much preparation and processing of the largest possible amounts of seawater in this fashion, during the coldest weeks of the year. It also requires a good way to transport and store this large mass of water.

Further information regarding existing and possible future desalination methods and other adaptive techniques could be found among the links below at last check:

Snow and ice provide ready sources of water when melted. Unfortunately, heat is necessary to melt significant quanitities of ice or snow-- and it's not advisible to directly eat much snow or ice for its water, if you're already chilled.

Rainwater-- as well as water from snow or ice melt or other sources-- still requires filtering and sterilization/purification to insure its safety for drinking.

Filtering out visible dirt and other particles from water may be done a couple of different ways. One is to simply let the contaminants settle out over a few hours, and then carefully pour the cleaner water off into another container. The other is to strain the water through multiple layers of cloth.

You can also construct a more substantial filter for this purpose, using fine, clean sand. But only where such a filter will be kept in continuous operation, full and slightly overflowing with water input. The basic principle is that your water will go through at minimum a two feet depth of sand on its passage through the filter, and you don't want more than four gallons of water an hour for each square foot of sand cross-section to flow through the device.

A wooden barrel or steel drum or custom-made container can be used. Allow a height including some four inches at top for water waiting to sink into the sand, then at minimum two feet of sand (the more the better), and finally three to six inches for a layer of small stones or pebbles roughly the size of peas in the bottom. Only a very tiny hole of barely more than one sixteenth inch in diameter should provide the outflow at the bottom of the filter.

You'll also want a small overflow hole and collector pipe near the top of the filter to re-route excess water flow.

Growth of bacteria in the sand is what performs part of the filtration process. Preventing sunlight from striking the sand will prohibit the growth of green algae. Maintenance consists of scraping the top quarter inch of sand off the pile when it's deemed necessary, and adding more sand to replace that removed after maybe three or four such scrapings.

Note that boiling or other purification of any water output from the sand filter is still recommended.

Plain old boiling of water (at sea level a minimum of five minutes, and adding another minute per each extra 1000 feet in elevation) will kill many dangerous organisms in it. It may also help reduce the likelihood of 'hard' water causing stomach upset (by causing some of the excess dissolved minerals to be purged as gaseous carbon dioxide). But boiling alone won't remove many possibly poisonous chemicals from water, as some of the techniques below will.

Can't spare the fuel for boiling? In hot regions SODIS may be applicable.

SODIS or Solar Water Disinfection is recommended by the United Nations for disinfection of water using soft drink bottles, sunlight, and a black surface-- at least in hot nations with regularly intense sunlight.

Water-filled transparent bottles placed in a horizontal position atop a flat surface in strong sunlight for around five hours will kill microbes in the water. The process is made even more safe and effective if the bottom half of the bottle or the surface it's lying on is blackened, and/or the flat surface is made of plastic or metal. It's the combination of heat and ultraviolet light which kills the organisms.

If for some reason neither boiling or SODIS is a viable option for you, you can use a chemical purification process (keep in mind boiling is often the absolutely safest method).

Chlorine bleach commonly used in laundry can also be used to sterilize water. At least when it comes from bleach where the active ingredient is sodium hypochlorite.

Use 5 drops of bleach per each half gallon of water to be purified, and allow it to sit undisturbed for half an hour to make it safe for drinking. Letting it sit several hours more will help reduce the chlorine taste, as the chlorine will slowly evaporate out.

(The 1980 reference below offers a figure of 5.25% sodium hypochlorite in bleach, while a check of the 2002 bleach on my own shelf says it has 6% sodium hypochlorite)

Don't have suitable bleach to apply to your water? Then you can use 2% tincture of iodine for the purpose, adding 10 drops to each half gallon of water to be purified, and letting the water sit undisturbed for 30 minutes before drinking.

A different reference advises when using household bleach for purification, add a single drop of bleach per quart of water which is visibly clear, or three drops per quart of water where the water is NOT visibly clear. Then allow the water to sit undisturbed for half an hour. If bleach is not available, substitute household iodine in the amount of three drops and ten drops for each case, respectively (and don't forget to let the water stand 30 minutes prior to drinking).

Other links related to chlorination of drinking water include Clorox.com Natural Disaster Preparedness Guide

So why is boiling water preferred over chemically treating it, to achieve purification? Several reasons. Just one is that during boiling even the water container itself gets sufficiently hot to sterilize all its surfaces likely to come in contact with the water as you pour it or drink it afterwards. But during chemical treatment only those surfaces actually touched with the chemically-enhanced water will be sterilized. So you could inadvertantly still sicken yourself by drinking from a container in which the water itself was purified-- but the up-to-that moment dry top of the container still harbored infectious organisms when you brought it to your lips for a sip. Keep in mind too that your purified water can be easily re-infected from a variety of sources after the chemical originally added to it has done its job, and dissipated or evaporated afterwards (this time period may be several hours or longer).

Concerned about arsenic in your water?

Arsenic can be removed from water using a bucket and local clays, in many areas of the world.

Mix together the arsenic tainted water with crushed local shale rocks in a bucket, then filter out the rock powder. Cloth of a form similar to that in jeans seems to do a good job as a filter.

Illite and kaolinite clays in the shale absorb the arsenic.

One cost-effective way of removing up to 95% of arsenic from well water is a process involving several clay pots.

Stack three unglazed clay pots atop one another. The two top pots should contain a mix of sand, charcoal, broken bits of brick, and chips of iron. Drinkable water will accumulate in the bottom pot.

The size of the pots used, and the number of different such purification systems set up for a single household, should be determined by the number of people to be provided for.

In Bangladesh the cost of a single such system was about six $US.

There's other methods of water purification as well, which can help clear out dangers besides arsenic and microbes.

A surprisingly cheap and simple way to detoxify contaminated water consists of dissolving carbon monoxide and oxygen into water containing undesirable organic chemicals, throwing in a bit of metal powder for a catalyst, and heating at 85 degrees C for a few hours. Finally, the metal is filtered from the liquid.

Transporting water from where it naturally exists to where it would be most convenient and useful may be no small feat in many cases. Especially if it must be done as cheaply as possible.

In an ideal situation, your house might be situated near the bottom of a natural waterfall, of a stream which runs year-round (but doesn't threaten your land with flooding even under the worst of circumstances. In that case you could simply build a pipe or trough framework to collect water somewhere uphill and feed it to your home at the bottom via gravity. Many variations on this gravity-feed system are available. Even one which can actually push water uphill to you, too.

Sometimes a hydraulic ram will serve well for this purpose. For example, it can pump water to a home which exists at a higher elevation than the stream from which its water is drawn-- using only the energy of the water itself. The energy consumed comes from the water falling a short distance prior to reaching the ram.

Ready-made rams can be bought, but a ram can also be built from scratch by anyone familiar with plumbing construction and repair.

Home Power magazine and Water-powered water pumps - Appropriate technology page offered further instruction on these matters, at last check. Other resources include a large number of plans and instructional how-to pdf files at Lifewater.org, and many plans and how-to files in HTML at Handpumps Resources. Handpump & Drilling Resources may also offer some useful tools and ideas.

People power or animal power may also be used to move water from place to place (even the goats mentioned elsewhere for food purposes may also be put to use pumping water). Hand pumps are used in many locales. Pedal-powered pumps also exist.

Miscellaneous other links related to creating or maintaining a safe supply of drinking water include:

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