RO VS DI Water:What is The Difference? -NEWater


In both household and commercial settings, reverse osmosis and deionization are two common water purification techniques. Both methods are efficient in removing impurities from water, but they operate differently and are most suitable for specific kinds of water treatment applications. So what is the difference between di water vs. ro water?

In this article, we will explore the differences between RO and DI, including how they work, their strengths and weaknesses, and when each method is most appropriate to use. These differences can help you choose the best water purification method for your needs.

Figure 1 Reverse osmosis Vs DI water purification.

➣Reverse Osmosis Water Purification

In the process of reverse osmosis, unwanted impurities in water are filtered out by applying pressure to the water on one side of the membrane forcing water molecules through the membrane and blocking impurities. Because of its relatively mature technology, effectiveness in removing contaminants, and lack of contamination, reverse osmosis is widely used for residential, commercial, and industrial water filtration.

Before using reverse osmosis to purify water, the raw water is first passed through a sediment filter to remove any solid particles. It then passes through a carbon filter to remove any remaining impurities, such as chlorine and other chemicals. The water is then allowed to pass through using a semi-permeable membrane that allows only water molecules to pass through while preventing contaminants from passing through.

Reverse Osmosis Systems work flow

As shown in the video below, the contaminants are dumped while the filtered water is collected on the other side of the membrane.

Pros of Using Reverse Osmosis Water Treatment

Reverse osmosis is a beneficial technique for water filtration for a number of reasons:

  • High efficacy: Reverse osmosis is a very effective membrane treatment method for purifying water of impurities, with a desalination rate of up to 99%.
  • Versatility: Reverse osmosis is a versatile treatment method that may be used to purify a variety of water sources, including tap water, well water, and seawater.
  • Eco-friendliness: Reverse osmosis does not produce any harmful byproducts, making it an environmentally friendly option for water purification.
  • Cost-effectiveness: Reverse osmosis systems may cost more upfront than some alternative technologies, but over time they are usually more cost-effective because of their high efficiency and few maintenance needs.
  • Convenience: Reverse osmosis systems are relatively easy to install and maintain, making them a convenient option for purifying water in both residential and commercial settings.

Reverse Osmosis Equipment Manufacturer

Limitations of Reverse Osmosis

Reverse osmosis is an effective method for purifying water, but it does have some limitations. For example, it requires a high level of pressure to force the water through the membrane, which can be expensive to provide. It is also relatively slow, and it can remove some beneficial minerals from the water, such as calcium and magnesium. However, these limitations can be overcome by using a process called remineralization, which adds back some of the minerals that are removed during the purification process.

➣Deionized Water Systems

Figure 3 DI water purification.

DI water, or deionized water, is water that has had almost all of its dissolved ions removed through a process called ion exchange. This process involves passing the water through a resin bed that contains ions with a charge opposite to that of the ions present in the water. The ions in the water are attracted to the ions in the resin, and as the water passes through the bed, the ions are exchanged.

This leaves the water with a very low concentration of ions, making it highly pure and suitable for many applications where ultra-pure water is required. Some common uses of DI water include laboratory testing, electronic manufacturing, and rinsing and cleaning in the food and beverage industry.

Pros of Deionized Water Systems

There are several advantages to using deionization to purify water:

  • High Purity: Deionization can remove ions from water to produce water with a very high level of purity. This makes it ideal for use in applications where pure water is required, such as in laboratories and in the production of pharmaceuticals and other sensitive products.
  • Flexibility: Water of various quality and ion concentrations can be purified by deionization. As a result, it can be used in a variety of settings to cleanse water.
  • Environmentally Friendly: Deionization generates little to no waste and does not produce any harmful by-products, making it an environmentally friendly option for purifying water.

Mixed Bed Deionizer for Food and Beverage Production

Limitations of Deionization

Deionization is typically used for water softening to remove contaminant ions such as calcium, magnesium, and chloride ions. However, deionization has some limitations that should be considered:

  • Limited Effectiveness: Deionization is not effective at removing all types of contaminants from water. It is only effective at removing ions, and cannot remove organic compounds, bacteria, or viruses.
  • Limited Capacity: Deionization systems have a limited capacity for removing ions, and will eventually become saturated and need to be regenerated or replaced.
  • Requires Regular Maintenance: Deionization systems require regular maintenance to ensure they are operating effectively. This includes replacing ion exchange resins and regularly testing the water to ensure that it meets the desired purity standards

Pros of Using Deionization to Purify Water

➣Differences Between Reverse Osmosis and Deionization

Two sophisticated procedures that are frequently used to cleanse water are reverse osmosis and deionization. Both methods clean water of contaminants, but they do it in distinct ways. The following are the primary distinctions between deionization and reverse osmosis:

1. Principle of Operation

Reverse osmosis is a separation process that relies on a partially permeable membrane to separate dissolved solids from water. The water is forced through the membrane under pressure, and the impurities are left behind. Deionization, on the other hand, uses ion exchange resins to eject objectionable ions from the water. The resins have a positive or negative charge, which attracts ions of the opposite charge. The ions are then exchanged for hydrogen or hydroxyl ions, which are released into the water.

2. Types of Impurities Removed

A wide variety of pollutants, including dissolved salts, minerals, and organic contaminants, can be removed by reverse osmosis. It is frequently used to clean contaminated water, brackish water, and seawater. Deionization, on the other hand, is primarily used to remove ions, such as sodium, calcium, and magnesium, from the water. It is not as effective at removing organic contaminants.

3. Efficiency

Reverse osmosis is generally more efficient at removing impurities from water than deionization. This is because the membrane used in reverse osmosis is able to remove a wider range of impurities, and it can do so with a high degree of accuracy. Deionization, on the other hand, relies on the exchange of ions, which is not as precise as the separation process used in reverse osmosis.

Pros of Using Deionization to Purify Water

4. Cost

Deionization is generally more cost-effective than reverse osmosis, as it requires less energy and maintenance. However, the cost of deionization depends on the quality of the water being treated and the type of resin used. Although reverse osmosis systems cost more to operate and maintain, they can deliver water of superior quality.

5. Applications

Many different industries, including water treatment, food and beverage processing, pharmaceutical manufacture, and power generation, use reverse osmosis and deionization. Reverse osmosis is often used to produce purified water for drinking, while deionization is commonly used to produce high-purity water for scientific and industrial applications.

➣RO Water vs DI Water, Which is Better?

Both reverse osmosis and deionization produce high-purity water, but they work differently and in different capacities. RO is more effective at removing dissolved solids, while deionization is more effective at removing ions. In general, RO is more suitable for applications where the presence of dissolved solids is a major concern, while deionization is more suitable for applications where the presence of ions is a major concern.

It’s also worth noting that both RO and DI have their limitations. Deionization may be less effective at removing certain types of organic molecules, and reverse osmosis may be less effective at getting rid of certain impurities, such as dissolved gases. To achieve the desired level of water purity, it may sometimes be necessary to combine reverse osmosis and deionization.

➣RODI Water System

A RO/DI system is a filtration stage with an additional “DI or deionization” device after the RO system, which removes 90% to 99% of impurities in the water and reduces the TDS (Total Dissolved Solids) of the water to zero.

RODI is a common deionized water system for laboratory. By modularizing the entire system, it has good integration, high space utilization, simple installation, reduced maintenance, and one-click access to high-end pure water.

DI system for lab


Although they function differently, in general, both reverse osmosis and deionized water filtration are effective technologies for removing contaminants in water and producing clean water. Deionized water purification uses ion exchange to remove ions and other contaminants, while reverse osmosis pushes water through a membrane to remove impurities. Both processes produce highly clean water, though reverse osmosis is usually more effective at removing a wider range of impurities.

In the end, the user’s unique requirements and preferences will determine whether reverse osmosis or DI water purification is best. NEWater is the ideal option if you’re looking for a reverse osmosis system or a DI water filter. Cutting-edge technologies, premium materials, and unsurpassed experience are used to build our devices. Please go to our website right now to place your order.

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