What is Brackish Water and How Do You Treat It?

Posted by
John Woodard on December 11, 2023

Access to safe drinking water is one of the great challenges in many parts of the world today. According to the World Health Organization (WHO), 1 in 3 people worldwide don’t have access to safe drinking water, and a global population expected to reach 8 billion by 2023 will further exacerbate the problem. Water comprises 71 percent of earth’s surface, but only three percent is fresh water, of which about one-third is drinkable. Evidently, there is no shortage of salt water on our planet, and a solution to the global water crisis may lie in the treatment of slightly salty brackish water. Brackish water contains salinity levels between  that of fresh water and seawater, making it considerably easier to desalinate than the latter. In this article, you can learn about brackish water, how it is treated, and how it may provide a solution to the world’s growing demand for drinking water.  

What is brackish water?

Brackish water is water that contains more salinity than fresh water but less salinity than sea water. Salinity refers to the concentration of dissolved salts in a body of water, so brackish water is saltier than fresh water but less salty than seawater. Brackish water has a salt concentration of 1,000 – 10,000 parts per million (PPM). In contrast, fresh water has a salt concentration of less than 1,000 PPM, and seawater’s salt concentration ranges from 30,000 – 40,000 PPM. Additionally, the total dissolved solids (TDS) level of brackish water far exceeds that of drinking water.

Learn More: What is TDS in Water & Why Should You Measure It?

The Environmental Protection Agency’s guideline for drinking water is less than 500 PPM, while brackish water is between 3,000 and 10,000 PPM. The easiest way to visualize brackish water is to picture where a river meets an ocean. The transition of fresh river water to salty seawater creates brackish water. These areas are called estuaries and are home to a wide array of plants and animals that have adapted to brackish water, such as mangrove trees and oysters.


Where is brackish water found?

Brackish water is found in estuaries, lakes, man-made pools and streams, and even aquifers underground. Estuaries, the most common source of brackish water, and other brackish water sources are present all across the globe. For example, as the Thames River in London meets the North Sea, as the Hudson River in New York City meets the New York Bay, and as the Amazon River in Brazil meets the Atlantic Ocean, estuaries are formed. The Caspian Sea , the world’s largest lake, contains brackish water because of an ancient ocean that once existed between Europe and Asia. Similar brackish lakes are found around the world, five of them located in India alone.

Man-made sources of brackish water include intentionally flooded marshlands for prawn farming and ensuing pools and streams from the construction of dikes built to control the flow of water from rivers and seas.

Lastly, brackish groundwater exists underground in deep fossil aquifers. Groundwater can be brackish as the result of ancient seas, due to saltwater intrusion in coastal areas, or if water absorbs an excess of minerals, such as sodium and chloride, as it percolates into the ground. In fact, about 75 percent of all groundwater in New Mexico is brackish. Private well water can even be brackish if it draws from a brackish groundwater source. In this case, the water needs to be treated before it can be used.

Learn more: What is groundwater contamination and how do you treat it? | Navigating saltwater intrusion

How do you treat brackish water?

Brackish water is treated with a water treatment system that is rated for desalination. Desalination is a process that removes dissolved mineral salts from saline water and converts it into fresh, drinkable water. Reverse osmosis and distillation are the primary desalination technologies used to treat brackish water. Seawater can also be desalinated through reverse osmosis and distillation, but the desalination of sweater is not as efficient due to higher salt content.

1.  Reverse osmosis

Reverse osmosis is the leading desalination technology in the world. A reverse osmosis system applies pressure to saline water and forces it through a semipermeable membrane. The membrane’s small pores block the passage of dissolved salts and other contaminants but allow water to flow through, converting brackish water into fresh water. One of the world’s largest reverse osmosis desalination plants in Israel can produce about 165 million gallons of fresh water each day.

Learn more: What is a reverse osmosis system and how does it work?

2. Distillation

Distillation is a desalination method that mimics evaporation in the atmosphere. Brackish water is heated until it evaporates into steam. Salts and minerals cannot evaporate as water can, so water condenses and resumes its liquid form when it is transformed into fresh water.

There are two primary distillation methods used to desalinate brackish water: multistage flash distillation and solar distillation. Multistage flash distillation is used in large-scale operations, while solar distillation is used in small-scale operations and in small communities.

Learn more: What is a water distiller and how does it work? 

Multistage flash distillation

In multistage flash distillation, brackish water is passed through multiple chambers where it is heated and compressed under high pressure. In each successive chamber, the pressure is reduced, causing the water to rapidly boil. The vapor produced in each chamber is then condensed and collected as fresh water. Saudi Arabia is home to one of the largest multistage flash distillation systems, producing about 200 million gallons of fresh water each day.

Solar distillation

In solar distillation, a pool of brackish water is covered by a transparent glass or plastic dome. Sunlight streams through the covering, evaporating the water and condensing it on the cover. The condensation, which is fresh water, then flows from the cover into a collecting trough.

Learn more: What is distilled water and is it safe to drink?

What is brackish water used for?

Brackish water is used in both its natural and freshwater state. In its natural state, brackish water is used primarily as a cooling agent in the thermoelectric power industry, oil and gas industries, and in mining applications. Also, brackish water can be used for irrigation in a practice known as saline agriculture. Certain crops, such as cabbage and oats, are salt tolerant and can be grown on salt-affected land while irrigated with brackish water. Saline agriculture is most common in the Middle East where it improves food security and reduces stress on scarce freshwater supplies.

Once desalinated, brackish water can be used as drinking water for humans and livestock. As freshwater scarcity intensifies, especially in arid, developing regions of the world, the treatment of brackish water provides an avenue to meet the mounting water needs of an increasing population. The presence of brackish water sources worldwide means it could reduce water scarcity, but as with every natural resource, brackish water resources must be used responsibly if they are to provide a long-term solution.

Can you drink brackish water?

No, you cannot drink brackish water because of it contains too much salt. If you drink salty water, your kidneys will overproduce urine to expel the excess salt from your body, leading to dehydration. However, when desalinated and treated, brackish water is safe to drink.


If you have further questions about brackish water or any other water-related concerns, please don’t hesitate to contact us.

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