What Is Desalination?

With water scarcity being a major issue in Australia and around the world, desalination creates a reliable water supply that is not dependent on rain. This incredible technology is now used by many countries to help create a sustainable water source.

But what is desalination? The simple science behind the desalination process is that it removes mineral components, primarily salt, from saline water. Read on to find out whether desalinated water is safe, more about the process, and the overall pros and cons.

Is Desalinated Water Safe?

Desalinated water is safe. All drinking water produced by desalination plants must meet strict quality standards. In Australia, these are set by the stringent Australian Drinking Water Guidelines (2006). Many desalination plants here are also fitted with delivery points, so that water authorities can regularly monitor water quality. 

The main problem with desalinated water, as with water from most other sources, is that it is still treated with fluoride, chlorine and other chemicals. These have their own set of issues, including affecting the taste and balance of your water, as well as potential side effects that are damaging to your health. 

Add to this the disinfectants that are put into our water to counteract the bugs, bacteria and organic matter in water pipes and you’re left with impure water and water devoid of beneficial minerals needed to hydrate. 

Water pipe

Choosing an effective benchtop water filter like the zazen Alkaline Water System, which removes and reduces up to 90% of fluoride, 99% of chlorine, and nasty chemicals, heavy metals and contaminants from drinking water and then importantly using natural mineral stones in the zazen bottom tank, adds back in the beneficial minerals (magnesium, potassium, chloride, sodium) which are essential in your drinking water for hydration.

Desalination and Water Treatment

Because Australia has severe issues with water scarcity, with many regions lacking any freshwater supply at all, we are at the forefront of desalination. Currently Australia has over 30 desalination plants, with every state in Australia now using desalination plants to help supply water.

Opening in 2006, Australia’s first desalination plant was the Perth Seawater Desalination Plant. Since then, it has been turning seawater from Cockburn Sound into nearly 140 megalitres of drinking water every day. This plant alone now provides 17% of Perth’s water needs

Perth Seawater Desalination Plant

Australia has desalination plants that follow these basic water treatment processes: coagulation, flocculation, sedimentation, filtration(using either distillation or reverse osmosis desalination method - outlined in more detail below) and disinfection of water

This turns seawater into drinkable water, which is fantastic. The trouble is, this process alters the natural chemistry of the water, stripping it of beneficial minerals and pumping it with chlorine and many other chemicals. By using a zazen Alkaline Water System, you revert the water to a purer naturally balanced form in a state ideal for hydration.

Desalination Methods

Seawater contains around 130g of salt per gallon. Desalination reduces these salt levels to well below 2g per gallon, the limit for safe human consumption. This desalination process is conducted using two main methods: distillationand reverse osmosis.  

Desalination dates back a long way. In the 4th Century B.C., Aristotle is regarded as the first to theorise how to remove salt from seawater. He suggested successive filters, but sadly was unable to invent them in his lifetime.

The first recorded example of desalination came around the year 200 A.D., when sailors were noted for collecting the freshwater steam from boiling saltwater. This began a trend of desalinating seawater with simple pans and boilers on ships. 

The sailors’ desalination method of evaporating water, which leaves the salt and other impurities behind, is a primitive form of the distillation method, or thermal desalination, which is still used today, albeit mostly by older desalination plants. 

This is because, since the 1950s, reverse osmosis has replaced distillation as the primary method of desalination. In simple terms, reverse osmosis forces seawater through a semipermeable filter membrane at high pressure, allowing water molecules to pass through but leaving the larger salt molecules (and chemicals) behind. 

For decades, the major hurdle for reverse osmosis was its cost. However, as technology has proliferated in recent times, seawater reverse osmosis has become more affordable, and thus a much more viable, attractive alternative to distillation. 

Over 2000 years after Aristotle originally envisioned the idea, reverse osmosis is now the primary desalination method used globally. The greatest challenge of desalination is the stripping of all minerals from the water, these minerals are required for the body to absorb water for the purposes of hydration. 

Desalination Pros and Cons

Providing water to the predicted 10 billion people expected to be alive in 2050 is one of the biggest challenges of the 21st century.  

Kathmandu City in Nepal

Moreover, water use has been growing twice as fast as population growth, causing more and more communities to suffer water shortages already. This drives the demand (and therefore prices) for freshwater supplies higher, making desalination increasingly attractive. 

Providing a climate-independent source of water for critical human needs and economic development (such as agriculture), and providing water security against the effects of climate change, a growing population and drought, are the main desalination advantages.  

Desalination works best in countries where rainfall is low, has coastlines (ideally close to major cities where demand is highest), and access to cheap energy and wealth to invest in and maintain desalination.  

The first desalination plants in the mid-1960s were hailed as a great solution that would make our oceans drinkable. But extracting salt is not without negative environmental impacts. 

Both the reverse osmosis and distillation desalination processes use a lot more energy, and thus produce a lot more greenhouse gases, than traditional water treatment methods. 

Smoking Chimneys of a Coal Fired Power Plant

Reverse osmosis requires large amounts of energy to generate the high pressure that forces the water through the filter. Current methods require about 14 kilowatt-hours of energy to produce 1,000 gallons of desalinated seawater

The increased energy demand means that desalination is more expensive than traditional water treatment methods too. Depending on local energy prices, 1,000 gallons of desalinated seawater can cost around $3 or $4 USD. By comparison, large-scale municipal seawater desalination projects in Australia cost approximately $1-$4 per kilolitre, with energy use representing 50-70% of total operating costs.

This sounds affordable but is often more expensive than pumping water out of the ground or importing it. The high cost of desalination also means that poorer countries that would benefit greatly from desalination simply cannot afford the infrastructure. 

Costs and logistical issues are then further compounded if desalination plants are a long distance from populated areas, as this requires long water pipes to be built and high volumes of water to be transported over large distances. 

The environmental cost of desalination is heightened when factoring in the very salty, slushy brine, the by-product of membrane desalination. Roughly 142 million cubic metres (equivalent to 56,800 Olympic swimming pools) is created and returned to the sea every day, together with chemicals used during the desalination process. 

Due to its dense concentration, this brine, enough to cover the entire surface of Germany, sinks and spreads along the seafloor, where it can interfere with entire marine ecosystems. As a pollutant, it must be disposed of carefully.

The good news is that breakthroughs in desalination are helping to lower the costs, energy consumption and its environmental impact. 

For example, in 2007, Australia's largest scientific research agency joined with nine major universities in a membrane research program to reduce desalination energy costs, as well as maintenance costs associated with gunk sticking to membranes and fouling them up.

Further positive news is that desalination plants are adopting more renewable energy too. For example, Sydney’s Desalination Plant can supply up to 250 million litres a day, which is up to 15% of its city’s water needs. And the plant is 100% powered by renewable energy. 

Renewable Energy

Many other Australian desalination plants are also powered by accredited ‘Green Power’, such as wind energy. But while this is beneficial to the environment, it can result in a significant increase in operating costs, due to the premium attached to renewable energy. But, as renewable energy becomes more affordable, desalination plants should too. 

Desalination At Home

Desalination is not just limited to industrial, large-scale plants. In fact, you can desalinate water at home, although these have a number of limitations. 

You may have seen a survivalist movie or video where someone puts water in a bowl, places a mug in the middle and covers it to capture the evaporated water and drip into the mug when put in a hot spot (either using the natural sun or any other form of heat). 

This rudimentary distillation method is similar to what the sailors used to do. Unfortunately, this bowl and mug method will not produce much water and is better suited for a science fair project than a sustainable source of water. 

A solar still employs much the same technique, just with a large hole in the ground as opposed to a bowl, with vegetation added in for extra moisture, and the hole securely covered with a large plastic sheet or similar. Fancy solar stills make use of more sophisticated and carefully constructed entrapments. Again, while this has its merits and charms, it is not a practical solution for most households. 

There are also a number of home water distillation systems that imitate desalination plant processes. These home water distillation systems can provide contaminant-free, drinkable water from seawater. However, these types of systems are often very expensive and critically lack the beneficial minerals required to hydrate. 

No matter how you get your water, be it desalination or not, the zazen Alkaline Water System can enhance it with electrolytes and key minerals to keep you hydrated and functioning at your fullest. 

We hope this has helped you learn more about desalination and the origins of your water. For more information about water and health, head over to our informative blog section.