Is Water from Reverse Osmosis Alkaline or Acidic?

September 20, 2023 5 min read

Is Water from Reverse Osmosis Alkaline or Acidic?

As nutritionists continue to discover new information about the body and its functions, the result is a growing interest in water quality and its impact on health. Water quality can be improved by your choice of water filter, but one filter in particular stands out for its ability to filter out even the most microscopic of contaminants.  Reverse osmosis (also known as RO) is known for being the most effective type of water filter (1). However, does running your water through an RO filter affect its alkalinity?

Understanding pH and its importance

When one speaks in terms of “alkalinity” and “acidity,” it is first necessary to understand what the  pH scale is. The pH is a number assigned to a solution on a scale of 0 through 14. The number assigned expresses how acidic or alkaline (basic) a solution is. The lower the pH, the more acidic the solution. The higher the pH, the more alkaline the solution. For reference, water has a neutral pH of 7, since it is neither alkaline nor acidic. 

The pH plays a crucial role in bodily functions. Your body and all of its organs require very specific pH levels to function effectively, and dramatic increases or decreases to its pH level can lead to negative health effects, like blood disease. It is important, therefore, to avoid eating too many acidic food/drinks that can take your body out of its equilibrium. 

Exploring the characteristics of water filtered through reverse osmosis

Reverse osmosis is highly effective in removing contaminants, and it boasts a removal rate of 98% of contaminants from its drinking water (2). It does this by “pushing water through a microscopically small filter material. Because of the microscopic pores on the semi-permeable membrane filter, reverse osmosis can… even remove dissolved substances from within the water” (1). RO relies mainly on water pressure to filter, so it is energy efficient and does not require electricity. 

However, because it is so effective in contaminant removal, it additionally removes any healthy minerals present in the water. This in turn decreases the water’s pH. Reverse osmosis water generally has a pH of 6.5, slightly below the neutral pH of 7 (3). This is around the same pH of bottled water, which is also slightly acidic. Tap water tends to range depending on geographic location, anywhere from extremely acidic to alkaline. Distilled water can fall as low as a 5.8 due to the lack of minerals in the water. 

Unraveling the pH of RO water

Typically, people assume reverse osmosis water is the best water for you because it is filtered so effectively. However, this is not the case when pH is considered. RO water has a pH of around 6.5, which is close to neutral but still acidic. This is due to the filtering out of alkaline minerals, like magnesium, calcium, and sodium, which raise the water’s pH. By filtering out these minerals, the water is more filtered, but not actually better for you. In order to try to raise the pH of reverse osmosis water back to neutral, you can try filtering your water through an alkalizing water filter. This will raise the water’s pH and come with its own health benefits.

Debunking common misconceptions

Myth: Reverse osmosis water is always perfectly neutral because it is nearly pure water, which is the definition of a pH of 7.

Fact: RO water is stripped of its naturally alkalizing, healthy minerals during the purification process. Therefore, it is acidic and has a pH lower than 7. By the time it is finished filtering in an RO system, the water has absorbed carbon dioxide from the atmosphere and has acidified. 

Myth: Reverse osmosis water is healthier than distilled, filtered, or tap water.

Fact: While fresh RO water is almost completely removed of dangerous contaminants, it does not include healthy minerals that are necessary for human health. Additionally, as the water sits out, an acidification process naturally occurs when water absorbs carbon dioxide from the surrounding air. To regain its healthy pH and healthy minerals, this water must be alkalized. Therefore, its health benefits are comparable to those from distilled or filtered water, as well as some types of tap water (pending geographic location.)

Benefits of alkaline water and its relation to RO water

Reverse osmosis water, as previously mentioned, has a pH under neutral, which means it is acidic because all of the healthy minerals were filtered out. However, there is a type of water where the healthy minerals are not only kept in, but embraced in order to raise the water’s pH. Alkaline water undergoes a purification process that increases its pH to about 8 or 9. While more research is still being conducted on the effects of alkaline water, it is believed to bring the body’s pH back to equilibrium. Additionally, consumption of alkaline water is cited to reduce heartburn, help with digestion, and improve acid reflux. To introduce alkalinity to your RO water (or your tap!), consider filtering it through a Seychelle pH pitcher

The Wrap-Up

Reverse osmosis water is one of the most highly filtered waters consumable. However, it is not necessarily the best for you. RO water is slightly acidic because all contaminants–even healthy minerals–are filtered from the water. The healthy minerals naturally found in water are called “alkaline minerals,” and they raise the water’s pH and provide your body with various health benefits, including reducing heartburn. In order to reintroduce these minerals into your RO water and reap the health benefits, try filtering your reverse osmosis water through a Seychelle pH pitcher. Your water will have a higher pH, and you will drink healthy, contaminant free water every time!

Frequently Asked Questions

Is reverse osmosis as good as alkaline water?

Reverse osmosis is effective in removing contaminants from water. However, it removes healthy minerals such as calcium and magnesium from the water, as well, which actually makes the water more acidic. Alkaline water keeps these healthy minerals present, which has positive health effects for the consumer. 

Does reverse osmosis water become acidic?

Yes. As healthy minerals are filtered out during reverse osmosis, the water becomes more acidic. 

What is the typical pH of reverse osmosis water?

RO water typically has a pH of 6.5, which is slightly acidic. 

Is it safe to drink reverse osmosis water?

Yes. Reverse osmosis is highly effective in removing contaminants from water, and it is safe to drink.

References Cited

  1. Chauncey Crail and Samantha Allen,Forbes Home,
  2. American Home Water & Air, 
American Home Water & Air,