Is Reverse Osmosis Water Acidic or Alkaline?

Last updated on January 2nd, 2023

In the world of drinking water there are many different kinds of water treatments. Some of them are better than others. The first two that come to mind are boilers and reverse osmosis. Boilers if often cost more because they require more space and labor, but generally requires that you change the filters less often. 

I say generally because some boilers don’t require you to change them. Reverse osmosis is a great treatment type unless you have really hard water or incredibly soft water or live in a really humid area. However, this is not true in all cases so don’t let me sway you too much on the treatment options without finding a solution that works for you.

Reverse osmosis water is one of the purest forms of water which has been proven to be beneficial for your health. But Is Reverse Osmosis Water Acidic? 

That depends on how you are looking at it. This article aims to give you a better understanding of what reverse osmosis water is, why it makes your water acidic, and the best ways to mitigate the problem.

Top 17 reasons why Reverse Osmosis Water is Acidic

The pH of reverse osmosis water is about 5.0, which is acidic. This is due to the fact that the process of reverse osmosis is designed to remove hydrogen from water. In order to do this, a small amount of acid is used in the process.

Ground Water Hardness

Many areas of the country have high levels of minerals in their water supply. This can lead to increased levels of hardness in the water and cause problems with scaling and corrosion for your appliances and pipes. Reverse osmosis will remove these minerals from your water, which can leave it with an acidic taste.

Ground Water pH

The pH level of groundwater can vary greatly depending on where you live and what type of area you are getting your water from. Groundwater has a tendency to be more acidic than surface water, but this isn’t always true as some areas have very alkaline ground waters that need treatment before they are safe for consumption by humans or animals alike.

Water Temperature

RO membranes are manufactured at temperatures of approximately 200 degrees Fahrenheit (93 degrees Celsius). When the water passes through the membrane, it absorbs heat from the membrane. This increases the temperature of the water and causes it to become more acidic.

Membrane Auto-Oxidation

Reverse osmosis membranes are made of polymers that have a negative charge on their surface. This negative charge attracts positively charged ions such as hydrogen and hydroxyl ions. 

These ions attach themselves to the membrane and begin to oxidize the membrane material. The oxidation of the polymers causes them to release free radicals into the water which further reduces its pH level.

Feed Water

Feed water can be naturally acidic or alkaline depending on where you live and what type of water source you’re using for your home’s reverse osmosis system. 

Some areas may have hard water with high levels of calcium carbonate which will contribute to an increase in acidity in your home’s RO system.

Others may have soft water with low levels of dissolved solids which will not impact your home’s RO system as much but could still contribute to an increase in acidity over time.

Water Softener Is Regenerating

The water softener regenerates by adding a brine solution to the tank. The brine solution is made up of salt and water, which dissolves into the water softener tank. 

The salt and water mixture is then pumped through the white resin beads, which remove the calcium and magnesium ions from the water. 

The calcium and magnesium ions are then passed through the black carbon bed and into the drain line. When this is happening, there is no water in your house.

Well Water Has Carbon Dioxide from Groundwater

If your well water has carbon dioxide (CO2) in it, it will be more acidic than pure rain water. The CO2 dissolves into the water and forms carbonic acid (H2CO3). 

This makes the pH about 7.4 instead of 8 for pure rain water. If you are concerned about this effect, check your local drinking water analysis report or ask your local health department for information on your area’s drinking water quality.

Acid/Alkaline Imbalance Caused By Other Factors

When you use an RO system, you’re removing several important minerals from your drinking water. These include calcium and magnesium — two minerals that are essential for bone health. 

These minerals need to be replaced if they’re removed during the filtration process; otherwise there will be an imbalance between acidity and alkalinity in your body, which can lead to serious health problems such as cancer or osteoporosis. 

Acidic Water Treatment Was Not Followed

The most common cause of acidic reverse osmosis water is the lack of basic addition after the system has been installed. Basic addition adds alkalinity back into the water to help balance out the pH levels. If your RO system does not have a basic addition unit, you should consider adding one to your system immediately.

Well Water Has Iron Bacteria in It

Iron bacteria are usually found in wells that are shallow and/or have high iron content in them from natural causes (such as iron pipes). If you live on a well and have an acidic reverse osmosis water problem, you may have iron bacteria in your well and not know about it yet!

Sulfur Reducing Bacteria Are Present

Reverse osmosis water has a pH of 3.5 or lower, and sometimes as low as 2.5. This is because it contains sulfate ions that are produced by sulfur-reducing bacteria in the RO membrane. 

Sulfur-reducing bacteria naturally occur in drinking water systems, but they don’t do any harm there because their numbers are limited by the amount of free oxygen in the water. 

However, if you use RO water for irrigation and/or as your primary source of drinking water, these bacteria will multiply quickly enough to produce harmful levels of hydrogen sulfide gas.

Mixed bed resin exhaustion

Mixed bed resins are used in the R/O system to remove all dissolved solids from the feed water. The resins can become exhausted when they have reached their maximum capacity for adsorbing contaminants. 

When this happens, they can’t remove more contaminants, even though they’re still being used. This causes the pH of the water to drop and make it acidic.

Resin bed exhaustion

The same thing that happens with mixed bed resins also happens with reverse osmosis membranes: The membrane becomes exhausted when its maximum capacity for removing solutes has been reached, causing the pH of the water to drop and making it acidic.

Ion exchange/cation exchange resin exhaustion

The ion exchange/cation exchange resin is the main component of a reverse osmosis system and it’s responsible for removing contaminants from the water. 

As time passes, this resin will become exhausted and can no longer remove all of the contaminants in your water. When this happens, you’ll see an increase in the pH levels of your water.

Carbon filter exhaustion

The carbon filters are responsible for removing chlorine and other contaminants from your water supply. 

As time passes, these filters will become exhausted as well and won’t be able to remove everything that they need to remove. This can lead to higher levels of chlorine in your drinking water as well as an increase in pH levels.

Water contact with air during storage and delivery

The air that is present in the water can lead to the formation of carbon dioxide (CO2) hydrogen carbonate or bicarbonate. This is because CO2 is very soluble in water, which means it dissolves easily in it. The more CO2 present in the water, the more acidity will be present.

CO2 (Carbon dioxide) solubility or saturation level in water is exceeded

The level at which CO2 becomes saturated in water may vary based on temperature and pressure, but it is usually around 400 ppm at room temperature. If this level is exceeded then an increase in acidity will be observed.

Conclusion: Is Reverse Osmosis Water Acidic

There are numerous reasons why a significant portion of the world’s population is acidotic. Although the main cause for this has nothing to do with Reverse Osmosis, it’s used by (and marketed to) many people who don’t actually need it and know nothing at all about Alkalinity, which can cause even more issues.

Reverse Osmosis water is trying to compete on a polluted and toxic playing field. It’s like a soccer team, who’s been practicing all year long and are ready to play their last match of the year, but they can’t because the other team hasn’t been preparing. 

That’s how these articles show that Reverse Osmosis Water is dying–because it’s up against much better products that have years’ worth of lab tests proving them.