What is Deionized Water and Soft Water?

You may have heard of the concepts of ionized water and softened water. Have you at some point thought about these questions: What is deionized water and what is softed water? What’s the difference between them?

In this article, we’ll give you an in-depth look at the definitions of deionized water and demineralized water. In addition, we will introduce how to make them and where can they be used. Get started now!

Figure 1 Water deionization system.

Contents hide

1. What are Deionized Water and Soft Water?

Deionized water: is typically high-quality potable water with a low or non-existent concentration of ionic contaminants. Essentially, deionized water is generated via a process referred to as deionization, which eradicates minerals from raw water. According to different water quality and usage requirements, the outlet water resistivity can be controlled between 1~18MΩ.cm.

Deionization further eliminates organics hence it is revered in industrial applications. Deionized water rarely has a nutritional value given most if not all of the suspended solids and minerals are ejected. Nonetheless, it might harbor certain odors or tastes.

Soft water: Also known as demineralized water. It is potable water devoid of hardness minerals like calcium, magnesium, iron, and lime. Water softening prevents the accumulation of deposits on pipes, water heaters, and other water treatment equipment. It also results in the removal of certain tastes and odors. Water hardness is graded based on the concentration of hardness minerals per million. Underneath are the distinct classifications of water hardness.

Water hardness in mg/L Classification
0-60 mg/L Soft water
61-120 mg/L Moderately Soft water
121-180 mg/L Hard water
Above 180 mg/L Very Hard water

2. What is the Difference Between Deionized Water and Demineralized Water?

Soft water is calculated based on calcium and magnesium ions in the water, and a water softening system cannot reduce the total salt content in the water. Deionized water equipment can remove all metal ions in the water. Ionized water is calculated based on the amount of minerals in the water.

Therefore, the difference between the two is that softened water is the product of reducing the hardness of raw water after being processed by equipment. The ideal deionized water has higher purity, fewer soluble salts in the water, and the water quality reaches the standard of pure water.

3. How to Make Deionized (DI) Water?

Complex industrial, laboratory, and pharmaceutical applications necessitate high-quality purified water devoid of ionic contamination. This is often achieved by deploying deionization systems, which largely utilize ion exchange. In some fields, reverse osmosis is also used to produce deionized water.

Deionization (DI) Water

-What is Ion Exchange?

Ion exchange is simply a water treatment process that substitutes objectionable ionic pollutants with less objectionable ions in a reversible process. The ionic exchange is facilitated by the ion-exchange resins, which demand frequent regeneration for optimum ion exchange. Principally, there are two types of ion exchange resins utilized.

  • Cation exchange resins.
  • Anion exchange resins.

Anion exchange resins harbor ions synonymous with negative charges such as hydroxyl (OH-), which they release in exchange for the anionic contaminants in the feed water. Cation exchange resins, on the other hand, substitute the cationic contaminants in the feed water with desirable cations such as hydrogen (H+).

The deployment of both cation and anion exchange resins facilitates base exchange and organic scavenging resulting in the production of high-grade product water devoid of all ionic contaminants.

Figure 2 The process of ion exchange.

-Deionization Unit.

Deionization water systems eliminate the ionic impurities present in feed water through two deionization processes.

(1) Two-bed Deionization Process.

Typical two-bed deionization systems are equipped with both the anion exchange resins as well as the cation exchange resins. First, feedwater is injected into the cation exchange vessel whereby the resins discharge hydrogen ions that disperse the cationic pollutants in the feed water.

Divalent cations such as magnesium and calcium are swapped with 2 hydrogen ions while monovalent cations such as sodium are substituted by a single hydrogen ion to sustain electrical balance,

Subsequently, the water from the cationic vessel is then passed through the anion resins. Here, the hydroxide ions from the resins are released and swapped for the anionic pollutants in the water.

(2) Mixed-bed Deionization Process.


Figure 3 mixed-bed deionization process.

Unlike the two-bed deionization system, mixed-bed deionization units have ion exchange resins blended in a single vessel (both anion and cation resins). As such, the quality of deionized water generated by a mixed-bed deionization system is superior to that generated by a tow-bed deionization unit.

Consequently, mixed-bed deionization is often deployed as a post-treatment process in reverse osmosis systems and two-bed deionization systems. Technically, it refines the water produced via two-bed deionization.

(3) Electrodeionization.

Electrodeionization is a contemporary deionization technology that runs on DC energy rather than chemical ions. It has been touted by many as the ideal substitute for mixed-bed deionization due to its effectiveness and efficiency.

Electrodeionization gets rid of the ionic contaminants from raw water without necessarily replacing them with less objectionable minerals. It is gradually gaining prominence in industries and laboratories because it does not generate lethal wastewater.

Figure 4 The process of electrodeionization.

-Reverse Osmosis System.

The reverse osmosis system process is a physical filtration process. The incoming water is forced into the system under high pressure, pushing the raw water through the membrane. The system uses a reverse osmosis membrane with nanometer-sized pores, so it can remove suspended solids, colloids, organic matter, viruses, and bacteria, as well as soluble salts, including mineral ions, from the water.
Therefore, after passing through the reverse osmosis system, the raw water is divided into two types of water flows, one side is pure water, and the other side is high-concentration salt water. The produced water is of high quality, thereby achieving the purpose of deionization.

Reverse Osmosis

4. How to Make Soft Water?

The main processes for softening water treatment include a dosing method, lime method, electromagnetic method, membrane separation method, and ion exchange method. Here we mainly discuss two types of water softening equipment, salt-based water softeners and salt-free water softeners.

-Sodium ion exchanger.

When the raw water with hardness passes through the water softener containing the resin layer, the calcium and magnesium ions in the water will be exchanged and adsorbed by the resin due to the principle of ion exchange, and the sodium ions will be released at the same time. Because sodium ions replace calcium and magnesium ions in raw water, the hardness of the water is reduced.

This process makes it difficult for carbonate scale and sulfate scale to form in the water, thereby obtaining softened water. Softened water can reduce the formation of scale, extend the life of appliances, and enhance the taste of water. Softened water can be used for circulating water applications in catering, food, chemical, pharmaceutical and other industries. It should be noted that when the resin absorbs a certain amount of calcium and magnesium ions, it will reach a saturated state and must be regenerated.

-Salt-free water softener.

Salt-free softening is a process that can replace cation exchange resin for softening. The entire process does not require salt washing to achieve the effect of scale prevention and descaling. The characteristics are no backwashing, no regeneration, no change in PH value, no waste water production, “0” operating cost, unchanged TDS (total dissolved solids), and short contact time.

Figure 4 Salt-free water softener system.

5. The Deionized Water and Softened Water Advantages.

In complex industrial, pharmaceutical, or laboratory applications, the use of untreated raw water with high concentrations as an ingredient or cleaning agent can put the entire process in jeopardy. To mitigate contamination of essential products or services, deionization, and water softener systems are deployed to supply first-rate softened water or deionized water.

-Why is Deionized Water Important?

In pharmaceutical manufacturing, deionized water is considered blanks because of its chemical composition, which permits its use as an impartial solvent. It harbors no impurities hence it does not risk contaminating the drugs or sensitive products it is used as an ingredient. The following are key advantages of using deionized water.

  • It mitigates the accumulation of salts and other impurities on vital equipment and distribution pipes. Therein, it prevents premature damage to the equipment thereby saving users repair and/or replacement expenses.
  • When utilized as an ingredient in the production of cosmetics or food processing, deionized water makes certain the end product is free from contamination.
  • When prescribed by doctors, deionized water can be consumed to aid the body in detoxifying. Consumption of deionized water should only be under the prescription of health experts given its intake could pose health risks to patients with mineral deficiencies.

-Why Do You Need to Use Demineralized Water?

  • Soft water reduces or avoids the formation of scale;
  • Helps extend the service life of household appliances;
  • Water quality is good, tastes better, and is good for the human body;
  • Suitable for washing and bathing;
  • Avoid issues such as energy waste and reduced efficiency of water equipment;
  • Industrial cooling water softening at a lower cost.

soft Water

6. Where Can Deionized Water and Softed Water be Used?

The growth of industrialization across the globe has driven an astronomical demand for deionization systems as industries seek to generate deionized water for product manufacturing. High-quality water is a basic necessity in most industrial processes hence the unlimited demand for deionized and soft water. Underneath, are key industries currently utilizing deionized water in various applications.

(1)Pharmaceutical manufacturing.

The manufacturing of pharmaceutical products such as drugs and water for injection necessitates high hygiene levels and the use of contaminants-free water. Deionization systems help pharmaceuticals to achieve the high-quality purified water necessitated for essential processes by eradicating up to 99.9% of ionic impurities found in tap water.

Deionized water can be polished using other water treatment processes like ultrafiltration, reverse osmosis, and ultraviolet radiation to meet the quality demands set by USP, JP, or Eur. Ph. The following are common uses of deionized water in pharmaceutical applications.

  • Supplying high-quality water for cleaning pharmaceutical equipment and appliances.
  • Generating excipients for medicinal formulation.
  • Safe solvent for diluting pharmaceutical solutions such as syrup.
  • Providing pharmaceutical-grade water for injections (WFI).


Various laboratories including hospitals, academic research, and industrial and agricultural laboratories mostly operate using highly purified water. The use of ordinary tap water in various laboratory experiments or activities could potentially alter the test results. Due to the sensitivity of biological, chemical, or agricultural tests, blank water such as deionized water is necessitated in laboratories. Common applications of deionized water in laboratories include cleaning apparatus, watering down concentrated solutions, and mixing various solutions.

Figure 6 Application of deionized water.

(3)Boiler feedwater.

To prolong the lifespan of boiler feedwater equipment, deionized or softened water is utilized because it is devoid of hardness minerals. The use of untreated raw water subjects your boiler feed to potential scaling and ultimately fouling. The use of deionized water in boiler feed has proven it can prolong the plant’s life service and avert premature damage.


The use of hard water in laundry results in excessive use of detergents as well as soiling, which essentially means your brightly colored clothes will have spots. To prevent all these, water intended for use in laundry applications is first softened using ion exchange, lime softening, reverse osmosis, distillation, and using chelating agents.

Other applications of deionized and softened water include:

  • A final rinse in car washes.
  • Fire extinguishing.
  • Food processing.
  • Manufacturing of cosmetics.

7. The Cost of Deionized Water and Soft Water.

(1) The Cost of Producing Deionized Water.

The cost of producing deionized water varies significantly depending on the quality of feed water deionized and the deionization technology utilized. To establish the cumulative cost of generating deionized water, you need to factor in the following variables, installation, labor, power consumption, regeneration, and maintenance expenses.

Figure 7 Water softener for households.

To aid you in understanding the operational costs of a deionized water system, we have broken down the operational considerations of a 14,000 GPD deionization plant. In this illustration, the overriding assumption is that the system runs continuously for 24 hours at a flow rate of approximately 10 GPM.

  • Replacement of Resins.

Most deionization systems necessitate a change of resins every once in 5 years. However, the period might be different for different water deionization systems depending on the frequency of use. A cation resin measuring 5 ft3 costs approximately $500 while an anion resin costs roughly $250 per ft3. Considering that the change is done once in 5 years, the total cost of resin replacement per month equals $38.

  • Consumables (regeneration chemicals).

If regeneration of both the cation and anion resins is carried out twice a day, the cost of each regeneration will be approximately $27.8. This is assuming that the price of HCL (32%) is roughly $0.24/lb. while the price of NaOH (50%) is $0.24/lb. Additionally, a single regeneration cycle consumes 3.5 gallons of HCL and 1.8 gallons of NaOH. This brings the monthly cost of regeneration chemicals to roughly $720.

  • Wastewater treatment costs.

The production of deionized water comes at a cost, there is a production of highly concentrated wastewater which necessitates treatment prior to disposal. A cation regeneration cycle generates 85 gallons of wastewater while an anion regeneration cycle results in 95 gallons of wastewater. Irrespective of the wastewater treatment process deployed, the average cost is roughly $70 per month.

  • Electricity costs.

The prevalent power voltage of a region often influences the electricity bills of a water deionization system. If the system is using 460V power, the monthly expenditure on power is approximately $35. This is assuming that the power consumption is billed at a rate of $0.10 per kW/h. Cumulatively, the total cost of producing 1000 gallons of deionized water is approximately $2.8.

(2) The Cost of Producing Softened Water.

Similarly, the cumulative cost of a water softener system can be classified into two broad categories. The purchasing price, which takes into consideration the buying price of the water softening equipment and the operational cost, factors in the installation, labor, power consumption, and maintenance expenses of the system.

To establish the overall cost of a water softener system, you have to calculate the total operational costs. The operational costs will vary significantly based on the water softening process deployed, the concentration of hardness ions in your feed water, and the size of the water softener.

For most users, the monthly expenses on water softener systems range from $10-$20. The differences in operational costs are accounted for by the difference in production capacities, desired water quality, and feed water quality.

8. Deionized (DI)Water and Soft Water Systems Types.

-Deionized Water System

There are varying water deionization systems manufactured with distinct specifications to generate different types of deionized water. Types of deionized or purified water vary from type II to type IV with the main difference being the conductivity, resistivity, and Total organic carbons (TOC).

To generate these distinct grades of deionized water, distinct deionization systems, and processes are employed. The following are popular deionization systems manufactured by NEWater.

* Dual bed deionization system.

As the name suggests, dual-bed deionized units are made up of two separate vessels. Cation-exchange resins are housed in one container while the adjacent vessel harbors anion exchange resins. For diversity, NEWater manufactures dual-bed deionization skids with varying exchange capacities ranging from 40k Grains to 800k Grains.

This ensures all our customers have their unique demands for deionized water well catered for. In addition, they have varying service flow rates ranging from 2 GPM to 135GPM. The key features of two-bed deionizers are:

  • Automatic regeneration.
  • Digital stager.
  • Tanks made of fiberglass.
  • Diaphragm valves.

Figure 8 Two-bed deionization system.

* Mixed-bed deionization systems.

Mixed-bed deionized systems have both the cation and anion exchange resins housed in one pressure vessel. The anion and cation exchange resins are rigorously blended and this allows the substitution of both cationic and anionic pollutants with hydrogen and hydroxyl ions respectively.

NEWater’s mixed-bed deionized systems are highly effective hence they are often deployed as stand-alone deionizers or secondary deionizers whereby they polish the deionized water from dual-bed deionization systems. The following are the basic features of our mixed-bed deionization skid:

  • Exchange capacities range from 62K Grains to 450K Grains.
  • Automatic regeneration.
  • Digital stager and upon request PLC.
  • Butterfly and diaphragm valves.
  • Flow rates range from 18 GPM to 190 GPM.
  • Carbon steel vessels lined with rubber.

*Water Electrodeionization Systems.

 Figure 9 Electrodeionization system.

Electrodeionization(EDI)systems utilize DC power and active media to eject ionic pollutants from feed water. EDI water systems are greatly revered because they do not necessitate the use of chemicals to deionize water hence they do not generate waste. Principally, EDI devices are deployed to polish water produced by reverse osmosis systems or two-bed deionization systems.

NEWater specializes in the production of electrodeionization systems with impeccable deionization rates, low operational costs, and compact modules. Our systems are highly versatile and are widely utilized in different industries to generate high-quality purified water. The basic features of electrodeionization systems include:

  • Production of high-quality water (up to 18 Megohm-cm).
  • Service flow rates range from 2 GPM to 220 GPM.
  • Compact structures.
  • Minimized chemical consumption.

(2) Water Softener Systems.

The dominant water-softening technology being utilized by households, industries, and businesses is ion exchange. Water softener skids make use of ion exchange resins to substitute undesired ionic impurities with less objectionable ions.

To generate softened water, the hardness minerals (magnesium and calcium) are swapped with sodium or potassium. Over time, the ion exchange resins become overwhelmed with the objectionable ions thereby obliging regeneration. The water softener systems manufactured by NEWater are broadly categorized into industrial or commercial water softener systems.

Industrial water softener systems.

Hard water is known for fouling valuable equipment and clogging pipes, boilers, and heat exchangers. As such, most industries utilize water-softener skids to avert the scaling effects of hard water.

NEWater provides varying water softener systems purposed to soften water for industrial applications like boiler feed water. Our industrial water softener units have the following distinctive attributes.

  • Automatic regeneration.
  • Exchange capacities range from 90K Grains to 4,200K Grains.
  • Tanks are made of fiberglass or carbon steel.
  • Flow rate ranging from 15 GPM to 1000 GPM.
  • Butterfly valves or diaphragm valves.

Figure 10 Industrial water softener skid.

Commercial water softener systems.

Unlike industries, most commercial enterprises do not necessitate high-capacity water softener systems. To ensure residential complexes, business offices, and other commercial entities have a cost-efficient solution to hard water; NEWater manufactures conventional small-sized water softener systems. Our commercial water softener systems are available in standard and customized versions. The following are key attributes of commercial water softener units.

  • Diverse exchange capacity ranges (10K Grains to 30K Grains).
  • Fleck control valves.
  • Tanks made of fiberglass (measuring 6-10 in diameter).
  • Diverse flow rates range from 8 GPM to 10 GPM.
  • Automatic regeneration.

9. NEWater Deionized System and Water Softener System.

The demand for water deionization skids and water softener systems keeps steadily rising as more industries seek high-quality purified water. For over 20 years, NEWater has fronted the production of water softener skids and deionization systems for various industries.

Equipped with unique and intelligent designs, NEWater’s deionization systems are guaranteed to offer your industry or business a cost-efficient solution to your water problem. Below, we expound on why you should procure your water softener systems and water deionization equipment from NEWater.

-Simple Installation and easy operation.


Figure 5 Water softener system.

The installation of NEWater’s deionization and water softener skids is pretty easy given most of them are plug-and-play. For skid-mounted systems, which are available on order, we assemble all components on a metal frame thereby minimizing the costs of installation.

With measures such as automatic regeneration, our water softeners and deionizers are considerably uncomplicated to use. This is further enhanced by our detailed and easy-to-understand user manuals. Additionally, NEWater provides free installation manuals via remote video tutorials and our customer support team is always available for consultations.

-High ionic-contaminant removal rates.

Our water deionization systems are highly proficient at eradicating objectionable ions from raw water and the deionized water generated rarely necessitates refinement. Depending on the requirements of your deionized or soft water, you can selectively utilize our two-bed deionization or mixed-bed deionization systems.

-No Highly Concentrated Wastewater from Electrodeionization.

In recent years, NEWater’s electrodeionization systems have increased in demand due to their effectiveness and overall cost-efficiency. A key advantage of Electrodeionization systems is that they do not utilize chemicals or salts to replace the ionic contaminants in feed water. This eliminates the possibility of having highly volatile wastewater thereby saving you the need for wastewater treatment.

-Automatic Regeneration.

With NEWater’s water softener units and deionization plants, you do not have to worry about regeneration given we have our systems fitted with meters or timed clocks. Over time, the objectionable ions derived from the feed water overwhelm the cation and anion ion exchange resins. At this point, regeneration is necessitated to uphold the production standards of the ion exchange resins.

Final Words

In the past 20 years, NEWater has provided various capacities of well water softening systems, deionized systems, EDI systems, and reverse osmosis systems to customers in different fields. By manufacturing high-quality water softeners designed to produce deionized water at an affordable price, NEWater is equipping industry, homes, and businesses with the necessary tools to combat water scarcity.

If you are interested in learning more about water deionization systems, and water softening systems, you can visit our webpage. For the latest quotes or technical consultation with our engineers, please feel free to contact us via email at info@newater.com. We provide factory-priced softening systems and deionization systems to customers around the world. We also welcome distribution of our products.

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