Collect and Purify Water

During short- and long-term emergencies, the most critical resource for you and your family will probably be potable water, especially if you live in an arid region. To prepare for such emergencies, and also to conserve water, you can practice rainwater harvesting.  Rainwater harvesting is one of the easiest ways to move towards self-sufficiency. Because we need water to survive, it is important not to rely completely on the system to provide it; redundancy is desirable in critical life-support systems such as water supply [1].

Because evaporation purifies water, rainwater is usually the purest water in the hydrologic cycle; you can therefore use it to water gardens without treatment. The simplest solution is to place a rain barrel (usually a 55-gallon drum with a valve) underneath the downspout of a rain gutter; the barrel should be placed as high as possible, keeping in mind that any support structure such as a stack of cinder blocks must be able to withstand the 450 pounds of a full barrel. Connect a hose to the valve and place it in your garden. The greater the height difference between the rain barrel valve and the hose outlet in the garden, the greater the pressure that drives the flow, and therefore the faster the water will come out of the hose. Rain barrels should have screens at the top to prevent debris or animals from entering the barrel [2]. Detains on how to construct a rainbarrel are given in [1], or you can purchase one prefabricated.

If during an emergency bottled or municipal tap water are not available and you plan to use rainwater for drinking or food preparation, you will need to go through some extra steps to make sure the water is not contaminated. Waterborne diseases cause nearly 15 million deaths each year. Disinfection kills the pathogens (bacteria, protozoa, parasites, and viruses) that can cause disease. Sterilization kills all living organisms in the water, bad or good. Purification removes potentially harmful chemicals in the water. A simple example makes the distinctions clear. You can disinfect water by pasteurizing it, which requires heating it to 149°F (65°C) for six to twenty minutes ([3], pg. 174). To sterilize the water, simply heat it to a hard boil in a covered pot. Boiling the water requires more energy for heating than pasteurization, but you can reduce the amount of energy required by tightly covering the pot to reduce heat loss. Pasteurization and boiling kill pathogens but do not remove dissolved chemicals such as the salts in seawater. To purify the water, you can remove the dissolved chemicals by boiling the water in an uncovered pot and collecting the condensed steam. Again, this is a very energy-intensive process. Below we will look at a few safe alternatives that require less energy.

The first step in water purification is to filter out suspended sediments that can hold chemical and biological contaminants by forcing the water through clean cheesecloth [2] or by temporarily placing the turbid water in a container to let the sediment settle out. Next, you need to remove biological contaminants that can cause disease. Boiling for ten minutes is the easiest solution. However, if you don't have enough fuel to treat all of your water this way, a more energy-efficient method is to use solar disinfection, termed SODIS ([1], [3]). Ultraviolet light kills the pathogens, and becomes more effective at high temperatures. Simply fix some shelves to a piece of metal painted black, then place bottles filled with water on the shelves and expose them to sunlight for six hours. You can paint the back of the bottles black so they will more effectively absorb sunlight and heat up to higher temperatures, killing the pathogens in as little as one hour [1]. In emergencies or while backpacking you can use iodine tablets, tincture of iodine 2%, betadine, or chlorine bleach to chemically treat water; see Lundin [3] and many other sources for detailed instructions on how to do this safely. There are other ways to kill pathogens, but most of them use high-tech devices such as UV lamps that need to periodically replaced or require electricity and are therefore unsustainable.

After filtering the water and killing the pathogens, most water will be safe to drink. For example, collected rainwater generally has very low concentrations of chemical contaminants, so it usually does not need to be treated to remove them. This is fortunate because it is much more difficult to remove dissolved inorganic chemicals from water. However, if you have reason to believe that your water contains chemical contaminants, you can use sunlight to evaporate the water and then collect the purified condensed water, a form of solar "still" ([4] pg. 471). The Watercone has an ingenious design that allows it to purify 1.6 quarts per day; it can even desalinate seawater ([5], pp. 193-4); see http://www.mage-watermanagement.com/. Or you can set up a still to collect steam produced by boiling water, as described above.

Following the simple procedures described above can help you provide potable water for you and your family during short- and long-term emergencies.

1. Kellogg, S. and S. Pettigrew, Toolbox for Sustainable City Living. 2008, Cambridge, MA: South End Press. 241

2. Bates, A., The Post-Petroleum Survival Guide and Cookbook: Recipes for Changing Times. 2006: New Society Publishers. 236 978-0-86571-568-4.

3. Lundin, C., When All Hell Breaks Loose: Stuff You Need to Survive When Disaster Strikes. 2007, Layton, Utah: Gibbs Smith. 449

4. Tawrell, P., Camping & Wilderness Survival. Second ed. 2006, Lebanon, New Hampshire: Paul Tawrell. 1080 978-0-9740820-2-8.

5. Steffen, A., ed. World Changing: A User's Guide for the 21st Century. 2006, Abrams: New York, NY. 596.

Case study: DuPont Plant, New Johnsonville, TN

For a number of years I took students in my graduate course Aqueous Geochemistry to tour the DuPont Plant in New Johnsonville, TN, about two hours west of Nashville. The plant manufactures Titanium Dioxide TiO₂ by mining the mineral ilmenite FeTiO₃ and reacting it Hydrochloric acid HCl as follows: FeTiO₃ + 2HCl = FeCl₂ (aq) + TiO₂ + H₂O. The Titanium dioxide is a pigment that gives Kilz paint, Oreos, and many types of toothpaste their brilliant white color. There are two problems with this process. One is that the product solution is still very acidic. The other problem is that ilmenite contains many toxic heavy metals that are soluble in the acidic solution. In the 1960’s when people didn’t know better, DuPont was allowed to dispose of hundreds of thousands of gallons of this toxic acid solution directly into the Tennessee River, which of course killed all fish and bottom feeders downstream. Later they switched to the more environmentally friendly but more expensive process of deep-well injection. They drilled wells between 1000-2000 feet deep and then pumped the acidic waste into a confined, deep limestone layer. The thinking was that the limestone (which contains calcite CaCO₃ and dolomite CaMg(CO₃)₂) would neutralize the acid: CaCO₃ + 2H⁺ = Ca²⁺ + H₂O + CO₂. The confining (impermeable) layer above would keep the waste isolated from shallow aquifers that supplied drinking water. Once again, there were two problems with this plan, which my class would remind the DuPont engineers of every year, and every year they would claim ignorance. First, the acidic solution dissolves the limestone, which results in the formation of large caves deep underground. Eventually the weight of the overlying rock layers causes them to collapse, breaking into pieces, falling, and filling the caves. This shatters the confining layer and makes it permeable, so that the wastes can rise up into the aquifers. The other problem is that, as shown in the reaction, limestone dissolution produces CO₂ gas, and the pressure of that gas can build until it shatters the overlying rock and escapes. Either way, it seemed likely that the confining layer would eventually be compromised. So, to their credit, DuPont came up with a new solution that was even more environmentally friendly but (they claimed) even more expensive. Since around the year 2000 DuPont has been reacting the ilmenite with sodium carbonate, and according to the DuPont engineers the only by-product is harmless FeCO₃ (the mineral siderite), which is used to make bricks for construction. However, recently it was learned that this process produces dioxin as a by-product. Pure Dioxin is the strongest poison known to man (it is the neurotoxin in Agent Orange), and the New Johnsonville Plant is the fourth-largest producer of dioxin in the U.S..

This case study illustrates many different points. First, it is difficult to anticipate all of the potential outcomes of a complex industrial process. That is why ecologists advocate the precautionary principle. Second, industrial chemistry sorely needs to be “greened”. Green chemistry is a field just now coming into its own, and it has the potential to reduce greatly the environmental impact of the chemical industry. Third, despite repeated attempts at trying to “green” the chemical process, the production of Titanium Dioxide still causes serious environmental problems. DuPont is being sued by numerous plaintiffs who live near or work at their Titanium Dioxide plant in DeLisle, Mississippi, who claim that dioxin has seriously damaged their health or caused the death of loved ones (http://video.google.com/videoplay?docid=-7693391300780002092). At New Johnsonville, TN, many citizens are afraid to talk about the health risks posed by the DuPont plant because they work for the plant, their livelihood depends on its success, and they fear retaliation (http://www.dupontsafetyrevealed.org/newjohnsonville.htm). This raises many questions: Should we allow chemical companies to manufacture goods like Titanium Dioxide that are nonessential (it is simply used for aesthetic reasons) but that cause great harm to human health and the environment? Or should we close the plants, even if it meant that thousands of people would lose their jobs? The plants in New Johnsonville DeLisle are by far the largest local employers, so closing them would be an economic disaster for those communities. In fact, years ago when DuPont reapplied to the State of Tennessee for a permit for deep well injection, a representative of the Tennessee Environmental Council asked me if I would testify against the application. I refused, saying that deep well injection seemed to be the best of the alternatives known at the time, and that I couldn’t bear the thought of helping to put all of those people in New Johnsonville out of work. Yes, I am pro-environment, so I believe we should always be looking for ways to protect the environment, but the overall benefits of change have to outweigh the overall negatives, and in this case, the economic vitality of New Johnsonville seemed to me to outweigh the potential risks of deep-well injection.

The Behavior of Water Pollutants

In their textbook "Ecological Economics" (2004), Herman Daly and Joshua Farley say that the limits to human population growth may lie not in resource depletion, but in the waste absorption capacity of the environment. This can be understood with the following analogy. Water purification filters usually contain a resin that turns color when it becomes saturated, i.e., it cannot absorb any more pollutants. The interface between the two colors of resin (the reaction front) will migrate through the column from the inlet towards the outlet. Water flowing from the outlet will be purified until the interface reaches the end of the column, at which point the column resin is saturated in pollutants and cannot absorb any more. From that time on the outlet water will be just as polluted as the input water. In this case, the waste absorption capacity of the filter has been exceeded. Our environment acts as a filter, purifying water that passes through it, but eventually the filter will become saturated.

Let’s examine this in a little more detail. What happens when the concentration of a pollutant in a sediment-water system (lake or stream) keeps increasing? Examine langmuir 10-007. Imagine that we pour uranium U into a beaker containing water and sediment. Some of the U will dissolve in the solution, but some will adsorb onto the surface of mineral grains in the sediment. At first the proportions of U in solution and adsorbed to sediment will be constant as the total U concentration increases (move along a straight line away from the origin). As concentrations get higher the number of available sites for U to sorb onto mineral surfaces begins to decrease, and a greater proportion of U enters the fluid, causing the adsorption isotherm to level off and approach a slope of zero when the adsorption sites become “saturated”. Eventually even the solution becomes saturated, i.e., it can’t dissolve any more U. What happens then? Any additional U added to the system will precipitate out as a U-rich mineral (in this case Schoepite) that is added to the sediment and therefore causes the sediment concentration of uranium to begin increasing again. Note that as long as the solutions remains saturated in Schoepite, any additional U we add will go into the sediment, increasing the U concentration in the sediment. Conversely, no matter how much additional U we add, the concentration of U in the solution is fixed at its highest possible concentration. In this case, we have saturated our filter.

Let’s look at some slightly more complicated models in which the sediment but not the solution becomes saturated. Polluted water enters a beaker with sediment, equilibrates with the sediment, and then is replaced with another batch of polluted water. At first, a large proportion of the pollutant will sorb onto the sediment, causing the concentration in the solution to decrease substantially. As more batches of polluted water equilibrate with the sediment, the concentration of pollutant in the sediment will increase, and therefore the concentration of pollutant in the water that exits the beaker will increase in direct proportion. As the sediment approaches “saturation”, it can sorb less pollutant, so most of the pollutant remains in solution, and our sediment filter become increasingly ineffective.

What if we stop polluting? Can the system recover? Start adding batches of fresh water. You would observe that the water that exits the beaker would at first have high concentrations of pollutant because our sediment filter was saturated in pollutants. But with time, the concentration of pollutant in the sediment and in the exiting fluid would decrease and eventually go to zero. Thus, we can “flush” pollutants out of a sediment-water system such as a stream or lake, but it may take a long time and a lot of fresh water to remove all of the pollutant, especially if the pollutant strongly sorbs to the sediment (which is why PCB’s are still in Hudson River sediments after many decades).

Now imagine a reservoir such as a swamp with one stream entering and one stream exiting. If the stream entering the swamp is polluted, sediments near its entrance point will strip pollutants out of solution. With time, a concentration gradient will develop across the swamp, with high pollutant levels near the input stream and low levels near the output stream. As polluted water flows across the swamp, it encounters sediments with decreasing pollutant concentrations, so the concentration of the pollutant in the solution will continuously decrease. The water becomes increasingly pure as it traverses the swamp. In nature, swamps do an excellent job of filtering pollutants from water. However, if pollutants continue to enter the swamp, the total pollutant concentration in the swamp will keep increasing. Eventually sediments near the input stream will become saturated, and that “saturation front” will slowly migrate across the swamp until it reaches the output stream. At that point the entire swamp system has become saturated, and the output water will be just as polluted as the input water. As in our beaker example, if we stop polluting and the water in the input stream becomes pure again, then over time the process will be reversed, and the pollutants will slowly be flushed out of the swamp.

Water Pollution Case Study: Lake Erie

I grew up in Buffalo, New York in the 1960’s and 1970’s, when pollution was reaching its peak in the rust belt and the environmental movement was beginning. One of the watershed moments in the environmental movement was the discovery in 1978 of toxic waste underneath a school in Love Canal, near Niagara Falls and very close to Buffalo. Until I was six we lived down the street from Lake Erie, and I still recall walking along the shoreline with a clean-up crew. The Lake was very polluted at that time; signs posted near fishing areas stated severe limits on consumption of caught fish due to the threat of mercury poisoning. Not that there were many fish to catch; the only type of fish anyone caught was catfish. Why only catfish? Because catfish don’t need oxygen in the water to breathe; unlike other fish who use gills to extract dissolved oxygen from water, catfish obtain their oxygen by gulping air when they come to the surface. The problem in Lake Erie and many other bodies of water at that time was that it was eutrophic, i.e., oxygen-depleted. In the process of eutrophication, limiting nutrients like phosphorous and nitrogen added to the water cause algae blooms. When the algae die, they decompose:

C6H12O6 + 6O2 = 6 CO2 + 6H2O

This consumes the oxygen dissolved in the lake water. In temperate regions such as upstate New York, lakes have two layers: a shallow, warm, buoyant layer and a deep, cold, dense layer. In a eutrophic lake, the shallow layer in contact with the atmosphere is oxygen-rich, but the deep layer becomes oxygen depleted because the dead algae sink to the bottom of the lake and decompose. In the fall and spring the density difference between the two layers disappears and they mix together. The problem is that, especially in the fall, the deep water has no oxygen, so when it mixes with the shallow water the resulting mixture does not have enough oxygen for fish to breathe, and they die in large numbers. This is still a widespread problem in many areas of the U.S.. In fact, there is now a huge “dead zone” near the Mississippi delta in the Gulf of Mexico that formed because fertilizer-derived nutrients caused algae blooms and eutrophication. The good news is that there is a solution. Simply removing phosphorous from detergents in areas surrounding Lake Erie led to a decline in algae blooms, and now the lake has mostly recovered. No one is worse off for using phosphate-free detergents, but for some reason in areas where regulations allow it (including my current home state of Tennessee) most detergents still contain phosphates, and eutrophication is still a problem.

Lake Erie is still not without problems. In summers, beaches are often temporarily closed after rainfall events. Why? Because wastewater disposal systems have limited capacity, and during heavy rains they fill up and then overflow into local streams, which flow to the lake. You may have noticed that water treatment plants and pumping stations usually have overflow ponds with pipes near the top that drain into a stream. When it rains, you can observe the overflow ponds fill up. Once they are full, any additional wastewater flows out through the pipe and dumps into the stream. Ironically, water in streams is usually dirtiest after rainfall events. Currently many cities are in the process of upgrading their wastewater systems under federal mandate. The problem is the same problem we face with highways; you can add more lanes, but traffic will build until a few years later it as just as congested as it was before you added the lanes. Population growth means that the ideal size of a service system is a moving target, and these systems frequently require expensive expansion projects. The city of Nashville had to increase its water bill in 2009 in order to pay for the expansion of its wastewater system, which will cost hundreds of millions of dollars.

Water

If there is magic on this planet, it is in water. Loren Eiseley, in “The Flow of the River”, The Immense Journey.

Water is already a limiting resource in many areas of the world, and has been so throughout human history. The earliest civilizations of Mesopotamia such as Sumeria most likely crumbled due to water shortages, specifically salinization of irrigated fields that caused food shortages, and the armed conflicts that ensued (see “Water Conflict Chronology”, Gleick, 2008).

Little [1] gives an example that provides a clear contrast between the sustainable approach and “business as usual”. When farmers in Garden City, Kansas learned from state and federal geologists in the late 1960’s that the water they were pumping was geologic water and would soon run out, they responded in two distinct ways. Most purchased more pumps and began pumping faster. Others like Rodger Funk chose to change their farming methods in order to conserve water and keep their farms viable when the groundwater ran out. Funk started using methods like no-till agriculture, and planted crops like wheat and grain sorghum that required less water. The goal was to rely only on rainwater by capturing and using all rainfall, which averages 18 inches in southwestern Kansas.

In his article “How Much is Clean Water Worth”, Jim Morrison [2] makes clear that investments in water conservation and in preserving ecosystems that provide fresh water pay for themselves. In the field of ecological economics, ecosystems are capital assets because they provide services such as clean water. For example, New York City relies on the Catskill Mountains to the north to provide fresh water. It was cheaper for NYC to preserve that ecosystem by spending $1.3 billion on upstate sewage treatment plants than it would have been to build a filtration plant in the city for $6-8 billion and operate it for $350-400 million per year. Thus, the value of the water that the Catskills provides is easily hundreds of millions, if not billions of dollars per year. The Catskills provide other ecosystem services such as flood control, food, and shelter, in addition to its scenic beauty and the recreation activities it provides such as trout fishing, both of which bring in lots of tourism dollars to the area. Another excellent example that Morrison [2] provides is the restoration of the Napa River in Napa, California to its original floodplain to reduce flooding. This project cost only $250 million, but it saved an estimated $1.6 billion in flood damage repair costs over the next century. And within one year of restoration, flood insurance rates dropped 20% and real estate prices rose 20%. There are many examples like this that illustrate that taking the soft path and relying on nature to provide ecosystem services is not only cost effective but preserves the beauty of nature.

The movie “Flow” [3] describes the problems of water exploitation by multinational corporations and the privatization of water supplies in developing countries. Since water-borne diseases are the leading killer of children less than 5 years old in the developing world, efforts to provide clean water in these countries should be a top priority. What is the best approach? Since water is essential for survival, we must consider access to clean drinking water a fundamental right. The chosen approach must therefore guarantee access to all. It is this one essential requirement that seems to have been overlooked in efforts to privatize water supply in countries like Bolivia. The World Bank pressured the government of Bolivia (which is deeply in debt to the World Bank) to privatize their water, which they did in 1999. Although the agreement was for the multinational corporation Suez to provide universal access to water, they neglected to provide water to the poorest citizens. Civil demonstrations turned into riots, and in 2007 the government rescinded their contract with Suez and returned the water to the people. In other countries like South Africa, even the poorest of the poor are required to pay for their water; when they cannot afford to pay, they are forced to steal water or drink unsafe water, which often leads to death.

Why didn’t privatization work in these countries? On the surface, it makes sense to contract a corporation with decades of experience to set up a water distribution system. This is a complicated, expensive task that many countries in developing countries are not prepared to execute. And when water is in short supply, it makes sense to treat it as a commodity, because charging for water encourages people to conserve it and not be wasteful. However, governments need to work with the corporations to ensure that they provide water even to the poorest. They should subsidize access to water so that the poorest do not have to pay. In the U.S. we subsidize food and water, heating oil, and telephone access, because these are essential needs (telephone access is necessary for emergencies). If private companies don’t build the water infrastructure in developing countries, who will? The government could oversee the planning and sub-contract the construction, but since it’s unlikely that anyone in the government has experience in developing water distribution systems, it’s doubtful that the process will be effective. Governments in developing countries need to work closely with multinational corporations to build their infrastructure. The goal is to build safe, reliable, and cost-effective water supply systems as quickly as possible to save as many lives as possible. The U.N. estimates that it would cost 30 billion U.S.D. to provide safe water to everyone in the world. This is a pittance; probably over 100 individuals in the world have that much money, and it could be used to save millions of lives each year. Ironically, 100 billion U.S.D. are spent each year globally for bottled water.

Another problem highlighted by the movie “Flow” [3] is the strong financial incentive for multinational corporations like Nestle and Coca-Cola to extract groundwater to bottle and sell. In most countries, including the U.S., you are allowed to pump as much groundwater as you please out of the ground, as long as you own the land. This is why smart people like T. Boone Pickens are extracting groundwater from their land for free and then selling it to cities. This policy is particularly unfair when multinational corporations like Coca-Cola buy land in developing countries, extract all of the water out of the ground at no charge, bottle and sell it for four dollars per bottle, and when the water dries up, pack up and leave the country. The indigenous people get no money from the sale of their most valuable resource, and they are left with no water. As long as people continue to pay outlandish prices for bottled water, there will be an incentive for corporations to exploit the developing world.

The movie "Flow" [3] and many other environmentally-themed movies and books paint a very bleak picture. That is because the authors are trying to motivate their audience and encourage them to take action to improve the situation. However, watching many of these movies or reading many of the papers may lead you to conclude that there are just too many problems and that we can never fix all of them. Just remember that you can always look at these problems in two ways: is the glass half empty, or half full? The reality is that several hundred years ago most human beings in towns and cities lacked access to clean drinking water, and a much higher percentage of humans died from water-borne diseases. In the developed world these diseases have been almost entirely wiped out, which was a huge accomplishment. What remains frustrating is that, although we know how to eliminate water-borne diseases, we haven't done so in many countries of the world. So while the situation has improved, it hasn't improved enough.

1. Little, J.B., The Ogallala Aquifer: Saving a Vital U.S. Water Source. Scientific American Earth 3.0, 2009.

2. Morrison, J., How Much is Clean Water Worth? National Wildlife, 2005: p. 24, 26-28.

3. Salina, I., Flow: For Love of Water. 2007, Oscilloscope. p. 84 min.