Is Reverse Osmosis Water the Same as Distilled Water?

Updated on:
March 6, 2024

Two methods of water purification are often touted as producing the cleanest water: reverse osmosis and distillation. But are distilled water and water filtered through reverse osmosis truly cut from the same cloth, or do they bear unique differences?

The truth is they’re not the same, not even close.

Let’s embark on a journey to demystify the realm of water purification as we filter truth from fiction. 

So, grab a glass of your favorite H2O and join me in unraveling the refreshing truth behind these two purification processes.

Reverse Osmosis and Distillation Defined

  • Reverse osmosis: Reverse osmosis is a water purification method that uses a special filter to remove impurities and contaminants from water.
  • Distillation: Water distillation is a method for purifying water that uses heat to turn water into steam, leaving impurities behind, and then cools the steam to collect pure water.


Reverse osmosis and water distillation, while distinct processes, do share some similarities in their goals and outcomes:

  • Purification objective: It may go without saying, but both reverse osmosis and distillation filter water by removing impurities, contaminants, minerals, and particles that might be present in the water source. They create cleaner, safer water suitable for drinking, cooking, and other uses.
  • Effectiveness: Both reverse osmosis and distillation are considered advanced water purification methods that provide a high degree of purity. They are often chosen for applications where exceptionally clean water is required, such as in medical settings or industries that demand stringent water quality standards.
  • Broad applicability: Both methods can be used to purify various water sources, ranging from tap water and well water to seawater and brackish water. This versatility makes them viable options for a wide range of settings, from households to industrial facilities.
  • Emergency situations: Both reverse osmosis and distillation can be valuable in emergency scenarios or when access to clean water is limited. With both methods, you can obtain purified water from questionable or unreliable water sources.

Despite these similarities, it’s important to note that there are also notable differences between reverse osmosis and distillation. Let’s take a closer look at both processes.

The Reverse Osmosis Process

Reverse osmosis (RO) is a highly effective water filtration process used to purify water in homes across the US. It’s particularly effective at removing a wide range of contaminants, such as dissolved minerals, bacteria, viruses, and pollutants, from drinking water.

Reverse osmosis is a process that removes contaminants from water by pushing it through a semipermeable membrane (also called a reverse osmosis membrane). This membrane allows water molecules to pass through but not dissolved salts, organics, bacteria, or pathogens. 

In a residential reverse osmosis system, the process begins with pre-filtration, where tap water initially passes through an activated-carbon filter to remove larger particles like sand, silt, and debris. This protects the reverse osmosis membrane from clogging. 

The water then enters the RO membrane chamber, where a high-pressure pump creates sufficient pressure to overcome the natural osmotic pressure and push water molecules through the semipermeable membrane. The membrane is designed to allow only water molecules to pass through, while rejecting dissolved salts, minerals, contaminants, and impurities. 

The purified water, known as permeate, is collected and stored in a clean water tank, ready for consumption.

The second stream of water, laden with concentrated impurities and contaminants, is called the reject or brine stream. This stream carries away the rejected substances and is usually disposed of down the drain. 

To enhance water efficiency and minimize waste, many modern residential reverse osmosis systems incorporate a process known as “crossflow,” in which a portion of the incoming water is directed along the membrane surface to flush away accumulated impurities and maintain the membrane’s effectiveness.

Advantages of reverse osmosis

A number of advantages can account for reverse osmosis’s popularity among households seeking high-quality drinking water:

  • Effective contaminant removal: A reverse osmosis water filter is highly efficient at removing a wide range of harmful contaminants from water, including bacteria, viruses, heavy metals, pesticides, and volatile organic compounds (VOCs). This ensures that the water you consume is clean and safe.
  • Improved taste and odor: The removal of impurities through reverse osmosis often results in improved taste, odor, and clarity of the water. This can make tap water more palatable and enjoyable to drink.
  • Minimal energy consumption: While a reverse osmosis system does require some energy to operate the high-pressure pump, its energy consumption is relatively low compared to other water treatment methods. This makes it a cost-effective option for water purification.
  • Compact: Residential reverse osmosis systems are typically compact and can be conveniently installed under the sink or in other small spaces, requiring minimal installation area.
  • Convenience and accessibility: Having a reverse osmosis system at home means access to a constant supply of purified water readily available for drinking and cooking. This eliminates the need to purchase bottled water and reduces plastic waste.
  • Customizable filtration: Some residential reverse osmosis filtration systems come with multiple filtration stages, allowing you to customize the system based on the specific contaminants present in your water supply.
  • Easy maintenance: Routine maintenance for residential reverse osmosis filters usually involves simple tasks like changing filters and occasionally cleaning the system. These tasks are straightforward and can be performed without professional help.
  • Water-softening capabilities: Modern reverse osmosis water filters can reduce water hardness by removing minerals that cause scale buildup on plumbing fixtures and appliances. This can extend the lifespan of your plumbing and appliances.
  • Removal of chlorine and chloramine: Many reverse osmosis systems include a carbon filter that effectively removes chlorine and chloramine from water. These chemicals are often used for disinfection in municipal water supplies but can affect the taste and smell of the water.
  • Peace of mind: Using reverse osmosis gives homeowners the peace of mind that the water they and their families are consuming is of high quality and free from a wide range of potential contaminants.
  • Versatile installation options: Reverse osmosis systems can be installed as standalone units or integrated into existing water treatment setups, providing flexibility in how you implement water purification in your home.
  • Longevity and durability: When properly maintained, the reverse osmosis membrane and system components can have a relatively long lifespan, providing consistent water purification over an extended period.

Disadvantages of reverse osmosis

It’s important to note that while reverse osmosis water filtration has many benefits, it also has some drawbacks:

  • Wastewater generation: One of the primary drawbacks of reverse osmosis is that it generates a significant amount of wastewater. Water scarcity can compound these concerns in affected areas.
  • Slow filtration rate: Reverse osmosis operates at a slower filtration rate compared to other water treatment methods. The high pressure required for the process can result in a relatively slow water flow, which might not be ideal for households requiring large quantities of purified water quickly.
  • Initial cost and installation: Residential reverse osmosis systems can be relatively expensive to purchase and install, particularly if you opt for models with multiple filtration stages or advanced features. The initial investment can be a deterrent for some homeowners.
  • Ongoing maintenance and costs: Regular maintenance is necessary to ensure the optimal performance of a reverse osmosis system. Filters need to be replaced periodically, and the system may require cleaning to prevent clogging and maintain efficiency. These maintenance tasks often include ongoing costs.
  • Energy consumption: While the energy consumption of reverse osmosis systems is relatively low compared to some alternative water treatment methods, the high-pressure pump still requires electricity to operate.
  • Selective removal of minerals: While reverse osmosis is effective at removing impurities, it also removes essential minerals like calcium and magnesium from the water. This can result in demineralized water that lacks some of the essential nutrients found in natural water sources.
  • Complex installation: Although modern systems are designed to be user-friendly, the installation process might require some technical knowledge and skills. Some homeowners might prefer professional installation, adding to the overall cost.
  • pH imbalance: The removal of minerals can result in a shift in the pH of the purified water, making it slightly more acidic. Drinking water with an imbalanced pH could potentially affect the taste of the water and the alkaline balance in the body.
  • Limited removal of certain contaminants: While reverse osmosis is effective at removing many contaminants, it might not be as effective against some dissolved gases, certain volatile organic compounds (VOCs), and extremely small particles. Additional treatment steps might be necessary for comprehensive purification.
  • Environmental concerns: The wastewater generated during reverse osmosis contains concentrated contaminants and can pose environmental challenges if not properly disposed of.
  • Impact on flow rate: Installing a reverse osmosis system can sometimes reduce the overall water flow rate in your home’s plumbing system, especially if the system is not sized appropriately for the household’s water usage demands.
  • Storage requirements: The purified water collected in the storage tank of an RO system might need to be used relatively quickly to prevent stagnation and the potential growth of microorganisms.

Considering these disadvantages as well as the advantages can help homeowners make an informed decision about whether a reverse osmosis system is the right choice for their residential water filtration needs.

The Distillation Process

Water distillation is a widely employed residential water filtration method that relies on the principles of evaporation and condensation. 

The process involves boiling water, causing it to vaporize and leave behind impurities such as minerals, heavy metals, and pollutants. These impurities remain in the original container water, while the water vapor rises and passes through a cooling system.

The cooling system typically consists of a condenser or cooling coils, where the water vapor is rapidly cooled and condensed back into a liquid state. This condensation stage transforms the vapor into distilled water, which is free from the majority of impurities due to the separation of the liquid from the contaminants during vaporization. 

However, some volatile organic compounds (VOCs) with higher boiling points than water may still be present in the distilled water.

The resulting purified drinking water is collected in a separate, clean container, ready for consumption. 

While effective at removing many contaminants, distilled water and its process have some drawbacks, such as its energy-intensive nature and the potential loss of beneficial minerals during the process. 

To address these limitations, some advanced residential distillation systems incorporate post-distillation mineralization stages to enhance the water’s taste and health benefits.

Advantages of distillation

The following advantages of water distillation make it an attractive method of residential water filtration, especially for use in cooking and baking:

  • Effective removal of contaminants: Water distillation is highly efficient at removing a wide range of contaminants, including heavy metals, minerals, bacteria, viruses, chemicals, and other impurities, as well as bacteria, viruses, and other microorganisms, and chemical contaminants, such as chlorine, chloramines, and certain organic compounds. 
  • Volatile organic compounds (VOCs) removal: Water distillation is particularly effective at removing volatile organic compounds (VOCs) with low boiling points. These compounds, often found in pesticides, herbicides, and industrial chemicals, are vaporized and left behind during the distillation process.
  • Mineral and salt removal: Distillation can effectively eliminate minerals and salts from water, producing water that is soft and free of hardness. This benefits people who prefer low-mineral content water or who have specific dietary needs.
  • Independence from water source quality: Water distillation can produce purified water regardless of the initial source’s quality. It’s effective at treating various types of water, including tap water, well water, brackish water, and even seawater.
  • Environmental considerations: Unlike some other filtration methods that require disposable filters or produce wastewater, water distillation generates relatively minimal waste. It doesn’t rely on consumable filter cartridges, reducing the environmental impact associated with filter replacements.
  • Simple maintenance: Distillation systems typically have fewer components that require regular maintenance compared to complex filtration systems..
  • Versatility: Water distillation systems are available in various sizes, making them suitable for residential use as well as larger-scale applications. This versatility allows homeowners to choose a system that matches their water consumption needs.
  • Chemical-free process: Water distillation is a chemical-free purification method. It doesn’t require the use of additional chemicals or additives, ensuring that the purified water remains free of such substances.
  • Long history of use: The process of water distillation has been employed for centuries, proving its reliability and effectiveness as a method of water purification.

Disadvantages of distillation

While water distillation offers these advantages, it also has some limitations including the following:

  • Energy required: A significant amount of energy is required to heat water to boiling point. This can lead to higher utility costs as well as contributing to a higher carbon footprint, especially if the energy source used for heating is not environmentally friendly.
  • Slow process: Distillation is a relatively slow method of water purification. This can limit the amount of purified water produced in a given time period, which might be a concern for households with high water consumption needs.
  • Loss of beneficial minerals: Water distillation removes not only harmful contaminants but also beneficial minerals present in water, such as calcium, magnesium, and potassium. Some people prefer water with a certain mineral content for taste and potential health benefits, and distillation might not provide this.
  • Initial cost: The initial investment in a water distillation system can be relatively high compared to other filtration methods. The cost includes the purchase of the distillation unit itself, as well as potential installation expenses.

Maintenance: While distillation systems generally require less maintenance than some other complex filtration systems, they still need periodic maintenance, such as descaling to prevent mineral buildup in the heating element or on the distillation chamber’s surfaces.

  • Limited pH adjustment: Distilled water tends to have a neutral pH due to the absence of minerals. Some people prefer slightly alkaline or slightly acidic water for taste or health reasons, and distillation doesn’t provide a convenient way to adjust the pH.
  • Space requirements: Water distillation units can take up considerable space in the home depending on application and water demand. This might be a concern for homes with limited space.
  • Risk of contaminant transfer: In cases where the distillation unit is not properly cleaned and maintained, there is a risk of contaminants building up inside the system and potentially transferring back into the distilled water, compromising its quality.
  • Inefficiency for specific contaminants: Some chemicals and compounds might evaporate and recondense along with the water vapor. Thus, it might not be the best choice for specific contaminants that have boiling points close to or greater than water’s boiling point, including some VOCs (volatile organic compounds).
  • Wastewater generation: Distillation produces some wastewater in the form of the concentrated impurities left behind in the distillation chamber. Proper disposal of this wastewater is important to avoid environmental impact.

Homeowners considering distilled water should weigh these disadvantages against the advantages and assess whether the method aligns with their specific water purification needs and preferences. If you do decide to drink distilled water, you may need to make sure you’re getting essential minerals from other sources.

Reverse Osmosis vs Distilled Water: Which Is Better?

Whether reverse osmosis water filtration or water distillation is better depends on your specific needs, preferences, and circumstances. You should base your choice on factors such as water quality, available resources, health considerations, and environmental concerns.

Reverse osmosis water filtration might be better if you prioritize these aspects of filtration:

  • Mineral retention: You might prefer some mineral content in your water for taste and potential health benefits; reverse osmosis retains some minerals, unlike distillation, which removes nearly all minerals.
  • Filtration speed: Perhaps you need a quicker method of obtaining purified water; reverse osmosis systems generally produce purified water faster than distillation.
  • Energy efficiency: Reverse osmosis systems typically use less energy than distillation.
  • Space constraints: Reverse osmosis systems can be more compact and less complex than distillation setups.
  • Moderate contaminants: Your water source contains moderate levels of contaminants, and you’re primarily concerned with removing common impurities like chlorine, sediment, and certain minerals.

Of course, distilled water is for you if you’re looking for something else from your filtration system:

  • High purity: Distilled water is free of a wide range of contaminants, including most volatile organic compounds (VOCs) and certain chemicals that are not effectively removed by reverse osmosis.
  • Pathogen elimination: Distillation’s high heat ensures complete elimination of bacteria, viruses, and other pathogens and microorganisms from your water. Distilled water is the purest water you can drink.
  • Emergency situations: Distillation can purify water from unreliable or contaminated sources, as distillation can effectively purify water from various quality levels.
  • Reduced energy availability: In some circumstances, for example if you’re off-grid, distillation can be set up using simple methods that don’t rely heavily on grid-based energy.
  • Removal of specific contaminants: Some water sources containing specific contaminants, such as certain volatile chemicals or heavy metals, are better filtered through distillation.

Ultimately, there’s no one-size-fits-all answer to which method is better; they’re both highly effective but come with downsides. 

It’s important to assess your priorities and needs, consider the advantages and disadvantages of each method, and seek expert advice if needed. In some cases, a combination of distilled water and reverse osmosis might be the most suitable approach to achieving the desired water quality.

Is Reverse Osmosis Water the Same as Distilled Water: Wrapping Up

While these two methods share the noble goal of providing water free from impurities, it’s clear that they dance to slightly different tunes. 

Reverse osmosis, with its semipermeable membrane, and distillation, harnessing the power of heat, stand as two distinct champions of purity. Reverse osmosis water retains a touch of mineral charm and is swift in its purification, while distilled water emerges as the victor when it comes to vanquishing the most VOCs and pathogens with its steamy embrace.

Whether you opt for reverse osmosis water or the distilled variety, each sip is a reminder of the benefits and ingenuity that science and technology bring to our lives.

If you have an interest in delving deeper into the comparison of different water filtration choices, there are several important factors you should consider. Feel free to check out our pages highlighting the best well water filters for more comprehensive details.

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