Reverse Osmosis vs Distilled Water

Both reverse osmosis (RO) systems and water distillers are renowned for their ability to reduce many types of contaminants in water. Both also are used in an abundance of homes in the United States. Both reverse osmosis systems and water distillers offer impressive contaminant reduction, so, you naturally may wonder which is the better fit for your home. Below you can find answers to questions about the similarities, differences, and advantages reverse osmosis systems and water distillers possess.

How are reverse osmosis and distilled water alike?

Both reverse osmosis systems and distillers are alike in their ability to eliminate the vast majority of contaminants from water and their environmental advantage over bottled water.

Removed contaminants

Both RO systems and distillers purify water by removing almost all contaminants. Both systems remove chlorine, chloramine, VOCs, heavy metals, and some bacteria and viruses. RO systems remove these contaminants by passing them through a series of filters, while distillers boil the water and cool down the resulting steam to a liquid state. Both RO systems and water distillers output water that is more contaminant free than most other filtration systems.

Environmental impact

While all filtration systems have some environmental impact, both home RO systems and water distillers have a much smaller environmental impact than buying bottled water. RO systems’ environmental impact stems from materials used in filter cartridges and wastewater during the filtration process. Many filters used in reverse osmosis systems are recyclable, so you should check the materials used in the filter before throwing it away. About 25% of water used in a home reverse osmosis system turns into the filtered product, while the other 75% carries the filtered contaminants down the drain. While 75% may seem wasteful, this “waste” is necessary to create safe, crisp-tasting water. The technology behind RO systems has greatly increased in the past decade, and reverse osmosis will only become more efficient in the future.

Distillers impact the environment through their use of electricity to heat water. About 3 kWh are used to distill a gallon of water. This costs the consumer about 30 cents on average. Since distillers are used almost exclusively for drinking water, less water is purified by a distiller than is filtered with an RO system. However, water for other purposes must also be purified by other means, so there is an additional environmental impact for those applications.

Both RO systems and distillers are far more environmentally friendly than using bottled water for drinking. About 40 billion plastic bottles are used in the world each month. Most of these are not recycled, and not all that are recycled end up as reusable plastic. The suggested water intake varies per person but generally falls between one-half gallon (64 ounces) and one gallon (128 ounces) per day. On the lower end of that range, this means that 4 plastic water bottles would need to be disposed every day for each person in a home. If there are four people living in your home, this total reaches almost 6,000 plastic water bottles used every year. Compare this to 4 or 5 thrown-away or recycled RO cartridges each year, and reverse osmosis filters come away as a clear winner in environmental friendliness. Likewise, the energy used to create the plastic bottles and transport them far outweighs the energy used to distill water for your home.

How are reverse osmosis and distilled water different?

Reverse osmosis systems and distillers are different in how they filter water, their efficiency, and their costs.


Reverse osmosis systems contain at least three stages, but distillers simply boil water and collect the steam. RO systems start with a sediment filter that removes large particles, followed by an activated carbon filter that removes chlorine, volatile organic compounds, organic chemicals, and more. The final stage of a three-stage RO system is the reverse osmosis membrane. In this stage, water is placed under pressure as it is forced through a semi-permeable membrane that contains tiny pores. This stage reduces levels of inorganic compounds as well as some viruses and bacteria. These inorganic compounds include heavy metals like copper, lead, and sodium. A remineralizing filter can be added to reverse osmosis systems to improve the taste and mineral content of the filtered water, and additional pre-filters and post-filters are sometimes added to further protect the RO membrane.

Distillers, on the other hand, are not filters in the traditional sense. They work by boiling water and collecting the resulting steam. The distillation process removes nearly all impurities from water if the system operates at the appropriate temperature. Because the boiling points of most contaminants is higher than the boiling point of water, the contaminants are left behind in the boiling chamber while the steam condenses on the ceiling and drips to a collection container. Distillation removes inorganic compounds such as metals and elements that contribute to water hardness. It also eliminates bacteria and viruses by killing them during the boiling process. Because distillers remove so many contaminants from water, distilled water typically contains a flat, bland taste that RO systems with a remineralizing filter do not have.



The speed of filtration is also vastly different between the two filtration types. A home RO system comes with a gallons per day (GPD) rating that tells how many gallons will be purified by a system per day. This Pentair Freshpoint reverse osmosis system, for example, can filter about 50 gallons of water per day if necessary. In contrast, an average home water distiller takes much longer to produce a single gallon than RO systems. This Pure Water Countertop Distiller, for example, can purify 0.88 gallons of water in about 3.5 hours. While this speed may be fast enough for a single person’s daily water intake, a distiller does not work fast enough to be used for most cooking applications. RO systems filter enough water in a day to be used for washing dishes, cooking, and drinking.


Point-of-use reverse osmosis systems cost anywhere from $200 to $1200, while home water distillers typically cost between $600 and $4000. Factors that affect RO system costs include the number of filter stages and the GPD rating of the system. Distillation cost factors involve the system’s size and efficiency.

The operating costs of an RO system involve purchasing new filter cartridges a couple of times a year, while distillers’ operating costs are more linear. You can expect to spend about $100 a year on replacement sediment and carbon filters for a reverse osmosis system. Every two years, you will need to replace the RO membrane, which ranges from $50 to $200. A distiller, on the other hand, is maintained by cleaning, not by replacing parts. However, the electricity used by a distiller takes up most of the operating costs. The average electricity cost in the United States is 10 cents per kWh. A distiller uses about 3 kWh to distill a single gallon of water, making the cost of home distillation about 30 cents per gallon. This makes reverse osmosis filtration much cheaper per gallon of water than home water distillers.

Advantages of reverse osmosis over distilled water

Reverse osmosis systems hold several advantages over water distillers.

Allow for remineralization

RO systems are commonly equipped with remineralization filters as the final stage of the filtration process. This gives water a better taste and the added benefit of healthy mineral content.

More versatile

Reverse osmosis systems come with a faucet attachment that can output water from a storage tank whenever needed. In extreme cases, reverse osmosis can even be used for whole-house filtration. This allows you to use RO water for applications such as cooking, washing dishes, and drinking. Distillers, on the other hand, only output enough water to be used for consumption.

Less expensive

Reverse osmosis systems are typically less expensive than home water distillers. Not only is the initial cost of an RO system typically smaller than that of a distiller, but the operating costs are smaller as well. Because RO systems output far more water more quickly than distillers, the cost per gallon of an RO system is much lower than that of a water distiller. Depending on how much water is utilized, a gallon of filtered water from a home RO system can cost as little as 0.4 cents. The electricity used by a distiller, on the other hand, costs about 30 cents per gallon.

Advantages of distilled water over reverse osmosis

While reverse osmosis systems hold the upper hand in many areas, water distillers possess some distinct advantages.

Can be used in rented spaces

RO systems attach to the plumbing in a home and, as a result, cannot be installed in an apartment. For those living in an apartment that want access to pure water, distillers are an excellent option.

Less complicated setup

Reverse osmosis systems often need water softeners attached before water passes through the stages of the RO filters. This prevents water hardness from building up on the RO membrane and causing damage over time. When purchasing an RO system, you must also decide how many stages of filtration you want and have the system installed under the sink. Distillers, on the other hand, are very simple to operate. They simply must be connected to a power source and provided water to distill.

Better at removing bacteria and viruses

While RO systems can remove most bacteria and viruses from water, bacteria can grow on the membrane and enter the water supply. For city-treated water, this is not an issue. However, if water is being sourced from elsewhere, such as a well, a distiller is more effective at eliminating bacteria and viruses than RO systems.

Used in many industrial applications

Because water distillers remove so many contaminants, distilled water is used to clean machines in hospitals, labs, and factories to prevent limescale buildup. It is also used in hospitals to cook food and to clean hands of medical professionals. The pharmaceutical industry also uses distilled water to prevent any unwanted reactions from occurring when mixing ingredients.

Frequently asked questions

Is reverse osmosis water and distilled water the same?

No. While RO water and distilled water are both pure, they undergo different purification processes that give them a different taste and contamination level. Reverse osmosis systems contain a remineralizing filter that prevents water from having a flat taste, but water distillers remove these minerals without adding them back in.

Can I boil water instead of using a distiller?

No, boiling water kills viruses and bacteria, but other contaminants will increase in concentration when water is boiled because of water lost in the form of steam. A water distiller catches this vapor and cools it down to a liquid while leaving the inorganic contaminants behind.

Do reverse osmosis systems remove water hardness?

RO systems are not water softeners, but water softeners can be added as a form of pre-filtration. If your water contains high levels of water hardness, adding a water softener can preserve the life of your reverse osmosis system.

Do reverse osmosis systems remove chlorine?

Yes, the carbon prefilter in an RO system removes chlorine before water reaches the reverse osmosis membrane. You may hear that reverse osmosis filters cannot remove chlorine, but these sources are referring to the RO membrane, not a full RO system.

Do reverse osmosis systems need electricity?

No, reverse osmosis systems rely on water pressure to power the system. If your water pressure is low enough where you need an RO booster pump, then electricity is required for your system to function.



Posted by John Woodard on July 16, 2022

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