Potable water is indispensable for human life. Where potable water is plentiful, it is often taken for granted. But it should not be forgotten that potable water is indispensable for human life because billions people worldwide are experiencing fresh water shortages. The shortages are certain to worsen in the coming decades.

The humanitarian crisis in Colombia’s La Guajira province (about 600 miles north of Bogota) is ample testimony. Between Northeast Colombia and Northwest Venezuela, La Guajira is a dry and windy peninsular desert with a breathtaking ochre and aquamarine coastline. The province is (about half of the size of New York) mainly populated by Colombia’s largest ethnic community, which includes nearly 300,000 members of the Wayúu ancestral tribe.

For decades their survival has been at risk. 

Abandonment of the state, corruption, and the misuse of natural resources have impoverished the region. As a result, the Ministry of Housing here in Bogotá has confirmed that 96% of people living in rural La Guajira do not have reliable access to potable water. Global warming, El Niño, and climate change are all now especially in play.

Fresh water on the 700 mile Caribbean coastline coastline is subject to inadequate desalination.  Greater increases in temperatures, especially inland, and declines in precipitation guarantee that livestock die and water to irrigate crops will continue to be insufficient. Thus, for both the coastal Wayúu, and inland, desert Wayúu, drought, in addition to widespread water contamination from the El Cerrejón coal mine, the lack of potable water contributes to poor hygiene and diarrheal diseases, which, with a diet lacking key nutrients, create a particularly high risk of mortality in children.

The Wayúu have a number of ancient traditions and rituals they keep alive, living in dispersed small, isolated social communities. A cluster of four or five  “rancherías” is typical, where families of upwards of 20 people live inside one mud, hay, and cactus hut. A well, or jagüey, for extracting and storing water might be shared between between multiple rancherías, and in times of drought long walks may be necessary to access the nearest water-containing jagüey. 

Once water is found it is often turbid, salty, or contaminated.

It’s in this way that a centralized, show case, high energy use, high capacity water treatment facility is a mismatch for the Wayúu, who need more dispersed, easy access to economical low-tech solutions for smaller volumes of potable water. The proposed $100 million aqueduct from the Rancheria River, now being endlessly debated in Bogota, is only the latest example of a poor solution.

For many years La Guajira has had hydrologic characteristics that do not allow it to be served well with a proposed network of aqueducts.  The size of the La Guajira and the semi-nomadic way of life of many communities are often cited. More recently, and more alarming, is that much of the water from the Rancheria River, the proposed inflow for the proposed aqueduct, according to El Cerrejón coal mining officials, is not suitable for human or animal consumption, or for irrigating crops. In fact, too much of that river water is being used  is for environmental dust control measures, as established in the mining company’s Environmental Management Plan.

Thus, a different, more immediate, proposal is to link the seawater of the 700 mile Caribbean coastline to inland La Guajira with desalination.
The most widely used desalination processes are thermal separation-flash distillation and membrane-separation reverse osmosis. Generally speaking, these are not patented processes. Thermal separation uses heat to separate the salts. Reverse osmosis uses micro filtration and mechanical water pressure to push salt water, or salt ions, through a semipermeable membrane.

Thermal separation

Thermal separation imitates the natural process of the water cycle, evaporation from the ocean, accumulation in the atmosphere, condensation in the form of rain or snow, and harvesting.

For solar-driven thermal application in La Guajira, it would begin by passing salt water, or simply brackish, water through solar collectors and a heat-saving ceramic-lined storage tank, where it’s heated to a boiling temperature, and then is gravity fed to another ceramic-lined storage tank, slowly to be drained on  steel surfaces which are already hot from solar radiation. Then the evaporation process begins.

A pilot demonstration organized by faculty and students  Universidad Nacional in Bogotá produces about 40 gallons of water a day. Enough for 25 people. “Our interdisciplinary group at designed the self-sustainable plant so the community can operate and manage it," said student Juan Esteban Quintero. Innovation matters. So, as reported in Nature Communications, the breakthrough efforts of a team of graduate students at MIT who dramatically reduced the undesirable fouling of salt accumulation with household materials holds the promise of improving reliability.

Portable membrane-separation reverses osmosis

A more portable, lower volume technology, has been developed by the NGO QuenchSea in London. The technology is membrane separation-reverse osmosis. A hand-held detachable lever operates a manually-operated hydraulic pump to build pressure to push water through both a pre-filter and a semi-permeable membrane that removes salts, bacteria, parasites, and microplastics. The antibacterial activated carbon fiber filter ensures that the taste is palatable and that the odor of the water was pleasant. Lab demonstrations in Bogotá produced a gallon fresh water in about 15 minutes. And as with the  thermal separation unit, the test for total dissolved solids (TDS) was acceptably below 1,000 ppm. The QuenchSea devices weighs about ten pounds. A similar product could be manufactured locally with readily available hydraulic pumps and membranes.

All of which has prompted many of us to rethink how critical green tech at scale is developed in the global South. Relatively inexpensive low-tech solutions are square pegs that don’t fit in the round hole of capital markets, investors, and bankers. Involvement by resource-strapped national, provincial (or state), and local government is crucial. In some ways, it’s the evolution of a science project to do-it-yourself practical adoption that often is simply overlooked, mainly because of little or no profitability.