How to Treat Your Salty Borehole Water？

Borehole water is a crucial water source in areas with limited freshwater resources, especially in rural regions, effectively meeting people’s basic daily needs. However, borehole water often contains various substances that can negatively impact water quality and health. If you rely on borehole water, keep reading. This guide explains how to select the right desalination solution to effectively remove salt and other harmful impurities, tailored to your specific water conditions.

Introduction of Borehole Water

Borehole water is obtained by drilling into the ground using mechanical equipment or manual methods to access underground water resources. Surface water, such as rainwater, river water, and seawater, filters through soil layers and sand, eventually collecting in the borehole. As a result, borehole water typically has lower levels of organic matter and suspended particles, making it relatively clear.

However, borehole water, due to the depth of the wells, often contains a high concentration of minerals such as calcium, magnesium, iron, manganese, sodium, potassium, and sulfates. These minerals can impact water quality. For instance, sodium ions can cause the water salty, while calcium and magnesium ions increase water hardness, negatively affecting taste. The quality of borehole water varies significantly by region, with coastal areas having higher mineral content. Additionally, the rocks in underground water layers can release heavy metals, particularly in areas near industrial wastewater discharge and mining operations, leading to elevated levels of heavy metals in the borehole water.

Why is Borehole Water Salty?

The quality of borehole water is closely related to the water source and soil environment. For instance, in coastal areas, the water obtained from boreholes is almost entirely seawater. Seawater can seep or otherwise enter the groundwater layers, increasing the salt content in the region’s groundwater. In addition, the soil itself is rich in minerals, primarily derived from the weathering of rocks. As groundwater flows through the soil layers, it naturally carries these salts and minerals, such as sodium chloride, sulfates, and carbonates, dissolving them into the water and causing it to taste salty.

The formation of salts in borehole water is also closely related to human activities. For example, excessive use of fertilizers, improper disposal of domestic and industrial wastewater, and large-scale deforestation leading to reduced vegetation can all contribute to the accumulation of salts in the soil. These factors can subsequently increase the concentration of salts in the groundwater.

Therefore, long-term use of untreated borehole water can be detrimental to health, potentially causing skin irritation, increasing the burden on the kidneys, and being unsuitable for individuals with hypertension. Besides, using borehole water can lead to the accumulation of salts in the soil, which is harmful to crop growth and unsuitable for animal consumption, negatively impacting livestock farming and breeding. In industrial production, directly using borehole water can increase equipment maintenance costs and adversely affect the quality of the final products.

How Can Salt be Removed from Water?

Borehole water typically has a high mineral content. While boiling can remove a small portion of the salts for drinking, it is far from meeting health standards or industrial plants requirements. Therefore, more specialized methods to remove salt are necessary, which is called desalination:

Water Softeners

Ion exchange filters use the exchange of ions on resin to replace specific salt ions and heavy metals in borehole water. For instance, common water softeners employ ion exchange to remove calcium and magnesium ions.

Also, ion exchange softeners can be designed with specific ion exchange resins to target certain ions such as iron, manganese, lead, chromium, and other heavy metal ions, as well as specific inorganic ions. This effectively addresses issues like high borehole water hardness, excessive levels of specific heavy metals, and yellowish discoloration.

However, ion exchange filters are generally more suitable for treating low-salinity borehole water. Suppose the borehole water contains high concentrations of sodium ions, chloride ions, sulfate ions, carbonate ions, and the like. In that case, it is advisable to consider nanofiltration and reverse osmosis filtration technologies for treatment.

Nanofiltration Filters

Nanofiltration technology uses selective permeability membranes that allow water and some dissolved salts to pass through while blocking larger salt ions, organic compounds, microorganisms, and heavy metals. Compared to ion exchange technology, nanofiltration can handle a wider variety of salt ions, such as sodium ions, chlorides, sulfates, carbonates, and some microorganisms found in borehole water. This enhances the taste and safety of the water.

Unlike reverse osmosis (RO) filters, nanofiltration filters can retain some beneficial minerals for the human body and usually operates with moderate energy consumption and water yield. Moreover, nanofiltration filters are highly effective and cheap, making them suitable for treating water sources with low to moderate salinity and for partial water quality adjustments.

Reverse Osmosis Filters

RO filters utilize membrane technology that selectively allows water and certain dissolved salts to pass through while intercepting large particles, salt ions, organic matter, microorganisms, and heavy metals. Compared to ion exchange technology, RO filters can handle a wider range of salt ions found in borehole water, including sodium ions, chlorides, sulfates, carbonates, and some microorganisms, thereby enhancing water taste and safety.

However, reverse osmosis membranes require high water quality input and typically need pre-treatment filters such as sediment filters and activated carbon filters. As a result, the initial investment for reverse osmosis systems is higher, making it suitable for users with higher budgets who prioritize the quality of their drinking water.

What is the Best Way to Remove Salt from My Bore Hole Water?

It is important to decide whether to purchase desalination equipment based on your local water quality standards, personal health conditions, and specific usage needs. Before making a purchase, it is advisable to test the Total Dissolved Solids (TDS) in your borehole water. For economic and practical considerations, home or small water treatment systems can use conductivity meters or salinity meters for testing.

Conductivity is an effective method for assessing the content of dissolved salts and other electrolytes in water. You can follow the below sheet to make a decision.

For home and small community use, we recommend considering a small reverse osmosis (RO) system. Even in cases where the raw water quality is challenging, these systems can effectively improve groundwater and efficiently remove various contaminants without occupying too much space. Prices typically range from $100 to $200, varying based on processing capacity and brand, allowing you to choose a suitable product within your budget.

If you prefer to remove most soluble salts, organic compounds, and heavy metals while retaining beneficial minerals, we suggest considering a nanofiltration (NF) treatment system. While NF systems are not as thorough in desalination as RO systems, they excel in terms of cost-effectiveness and applicability, especially suitable for situations where water quality requirements are not extremely stringent or where the raw water quality is already good.

NEWater also offers high-quality small RO systems and NF systems for moderate water volumes, aiming to provide clean water sources at affordable prices to more communities and residents. You can visit our water purifier product page🔗 or contact us for professional advice on equipment purchase.

Faqs:

What are the chemicals to remove salt from water?

The desalination process does not solely rely on the use of chemical agents. Chemical additives for treating salts in borehole water are typically employed within treatment systems, such as antiscalants to protect membrane performance in reverse osmosis units and membrane cleaners. Depending on specific needs, pH adjusters can also be added strategically to enhance treatment efficiency. Commonly used additives include coagulants, flocculants, and biocides, among others.

How to treat borehole water naturally?

For large particulate impurities in borehole water, such as sediment, stones, and suspended solids, sedimentation methods can effectively remove these insoluble substances. However, for soluble salts in borehole water, relying solely on simple methods like boiling or sand filtration without chemical agents or specialized equipment results in low efficiency and suboptimal outcomes. Moreover, these processes may risk contamination from other impurities. Therefore, consulting experts for professional treatment methods is advisable when dealing with salts in borehole water.

When should I choose reverse osmosis (RO) for salty borehole water?

When the well water has a high salinity, such as TDS exceeding 1000 ppm, and your target water quality is for direct drinking, you should choose an RO system to treat the well water. RO technology effectively reduces dissolved salts in well water while removing various contaminants, ensuring safe and clean product water.

Why is nanofiltration (NF) sometimes better than RO for borehole water?

Because nanofiltration can also efficiently treat well water with moderate salinity, and its overall cost is generally lower than reverse osmosis (RO), making NF systems more advantageous in certain applications.

Furthermore, NF can retain some beneficial minerals in the raw water while removing target dissolved salts and contaminants, making it suitable for applications with less stringent requirements for effluent quality. Nanofiltration systems operate at lower pressures and consume less energy, further reducing overall operating costs.

What salinity level of borehole water requires desalination treatment?

Well water with a salinity exceeding 500 ppm requires desalination treatment. If the concentration exceeds 1000 ppm, mandatory treatment is required to meet drinking or agricultural water standards.

Can boiling or sand filtration remove salt from borehole water?

Neither. Boiling only kills some bacteria in well water; dissolved salts, due to their high boiling point, will not evaporate with the steam. While sand filters can trap most large particles of sediment in well water, dissolved salt particles are extremely small and can easily pass through the sand filter layer. Therefore, neither method is effective in removing dissolved salts from water.

How to decide whether to install a desalination system for home use?

First, you need to test the salinity (total dissolved solids, TDS) and taste of your raw water.

If the water is too salty or tastes bad, and you don’t have a reliable municipal water supply, then investing in a home desalination system is well worth it. It can provide you with a stable, independent source of clean drinking water.

What pre-treatment is required for RO or NF systems?

Pre-treatment for reverse osmosis (RO) or nanofiltration (NF) systems typically requires sand filters and activated carbon filters. Sand filtration removes suspended solids and large particulate impurities from the raw water, while activated carbon eliminates chlorine and some microorganisms.

Pre-treatment is essential for membrane treatment. It effectively reduces water turbidity, prevents membrane elements from becoming clogged by contaminants, and extends membrane lifespan. It also ensures stable and efficient system operation, guaranteeing that the product water quality meets standards.

Is nanofiltration worth it for small-scale applications?

Yes, nanofiltration (NF) technology is ideal for small-scale applications such as homes or small communities. It is economical and practical, especially when treating water sources with moderate salinity, producing water that consistently meets drinking or light irrigation needs. It effectively removes some salts and contaminants while retaining some natural minerals, resulting in lower overall investment costs, lower operating energy consumption, and relatively less maintenance requirements.

Can treated borehole water meet drinking water standards?

Yes. With proper treatment, well water can meet stringent drinking water standards.

By combining suitable technologies such as reverse osmosis (RO), nanofiltration (NF), or ion exchange with appropriate pretreatment and post-treatment processes, dissolved salts, suspended solids, bacteria, viruses, heavy metals, pathogens, and other harmful contaminants can be effectively removed.

What affects the choice between ion exchange, NF, and RO? 

The choice depends on several key factors, including feed water salinity, budget, energy consumption, required water quality, intended use, and maintenance requirements.

For applications with high salinity water or requiring high-purity drinking water, reverse osmosis (RO) is generally recommended. For medium salinity water, limited budgets, or non-potable water applications, nanofiltration (NF) or ion exchange systems may be more suitable.