While Earth is rightly dubbed “the blue planet” thanks to its vast oceans, this terminology falsely alludes to a supply of abundant, consumable water. In truth, only 2.5 per cent of the Earth’s water is fresh; that is, consumable by both humans and typical plant species. Moreover, a majority of this fresh water is contained in snow and ice—leaving only 0.3 per cent of Earth’s water available to be utilized.
Through the past decade, as vast areas of the planet experienced water shortages, the global populace has recognized the need to for novel water sources. The most blatant option is the ocean; however, our vast reserves of seawater cannot be utilized for human consumption or crop irrigation without extensive desalinization treatment.
Traditionally, the desalinizing of seawater as a source for drinking water has been viewed as unpractical. This is largely because, on a molecular level, the water and salt bonds within seawater are notoriously strong (see: soluble salts).
As a result, the desalinization process requires a huge amount of energy—meaning that it is a very costly enterprise, both environmentally and financially.
Still, for inquisitive homesteaders looking to desalinate water for drinking and irrigation, there are a couple of options:
Solar Stills for Desalinization of Sea Water
Solar stills have been used to desalinate water in survival situations on boats and islands for generations. Most marine-based first aid/survival kits include compact solar still kits to be used in emergency situations.
Solar stills function in a similar way to a salt pond, except it traps evaporating fresh water molecules. Essentially, a clear plastic or glass cover is sealed air-tight over a salt water reservoir then set under the hot sun.
As fresh water evaporates from the salt pond, it condenses again into liquid form on the clear covering. To aid in the process, the clear cover should be situated in an angular fashion. This positioning ensures that the condensed water molecules eventually drain down the interior surface of the clear covering and into an awaiting tube or container.
It should be noted that solar stills work quite slowly and they are rendered obsolete on cloudy days. Therefore, if individuals are serious about desalinating large amounts of water with solar stills, they should construct a large number of these rigs and take advantage of sunny days.
Thermal Stills for Desalination of Sea Water
Thermal distillation is relatively easy to accomplish at home and is a popular method for creating drinking water in survival situations. It utilizes heat to boil salt water, a process that separates the water and salt molecules.
Simply fill a metal container partially full of seawater and boil it over a heat source. Next, place a tall dish in the middle of the container with the boiling salt water. The top of the small dish must be well above the salt water line.
After that, a convex lid (the curve faces downward) must be placed atop the larger metal container, forming a relatively tight seal. The center of the lid must be directly over the midpoint of the tall dish. If the system is set up correctly, the steam from the boiling salt water will condense on the convex lid and drip distilled water into the interior tall container.
It’s apparent that as humanity’s need for water rises, technology will have to keep up with the demand. On a large scale, oil-rich desert countries such as United Arab Emirate and Saudi Arabia have initiated massive desalinization programs to supply their people with potable water.
Large-scale desalinization efforts will also likely spread west, as the average American citizen uses approximately 130 gallons of fresh water on a daily basis. This staggering statistic represents a misguided sense of fresh water abundance; this ideal becomes blatantly evident in times of water crisis such as the California drought of 2012-2016.
Until those large-scale projects become the norm, at-home desalination is an option that can be used to alongside reduced water usage, such as watering gardens with extra grey water from showers and dishes.