What Effect Does Carbon Dioxide Have on Tap Water?

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Carbon dioxide – the gas we exhale during respiration – is found in varying levels in our tap water.

Often, carbon dioxide is found naturally in water. Other times (in the case of carbonated water products), it’s added intentionally to water.

How exactly does carbon dioxide end up in tap water, and how might it affect the water quality? We’ve answered these questions and more in this guide.

📌 Key Takeaways:

  • Carbon dioxide gets into water through rainfall, organic matter, plants and aquatic life, and water pollution.
  • CO2 reduces water’s pH level but shouldn’t otherwise have an effect on water’s taste, smell, appearance, or quality.
  • You can remove carbon dioxide from drinking water by sending the water through a tank containing limestone chips.

📥 How Does Carbon Dioxide Get Into Water?

There are a few different ways that carbon dioxide might get into water:

  • Through rainfall – When precipitation occurs, rain falls through the air, which contains trace amounts of carbon dioxide. Some of the carbon dioxide gases are absorbed by the rain. The rainwater then lands in bodies of water that may be used as public drinking water supplies or travels into water sources from the land via surface runoff.
  • Through organic matter – Organic matter, like decaying plants and leaves, releases carbon dioxide as it breaks down. When water seeps through soils containing organic matter, it picks up some of the released carbon dioxide gases. This water may then collect in a groundwater source, such as an underground aquifer supplying a private well.
  • Through plants and aquatic life. Plants and fish also release carbon dioxide into natural water sources.
  • Through water pollution. Carbon dioxide is emitted into the earth’s atmosphere through a number of human activities, including energy production (burning fossil fuels), and other chemical reactions (such as manufacturing cement). This atmospheric CO2 will be absorbed in liquid form by the earth’s water sources.
Carbon dioxide from burning fuels at industrial plants

🚰 How Much Carbon Dioxide Does Tap Water Contain?

The level of carbon dioxide in water from a tap depends on the water source and its exposure to the influencing factors listed above.

If you live in an area with a higher-than-average amount of carbon dioxide emissions, your water might contain more carbon dioxide than other drinking water supplies in other regions.

There’s no way to know how much carbon dioxide your tap water contains without using a test kit or doing a lengthy science experiment, and we couldn’t find any information online about the average amount of carbon dioxide in tap water.

📌 Note: A couple of websites gave an average “carbon footprint” for tap water, but this has nothing to do with how much carbon the water contains – it’s actually a measure of how much energy is used to produce the water, which is irrelevant to the question.

🔎 What Effect Does Carbon Dioxide Have On Tap Water?

So, now you know how carbon dioxide gets into water – what effect might it have on your tap water quality?

Chemical Effects Of Carbon Dioxide in Water

In chemical terms, carbon dioxide reacts to decrease water’s pH level and increase its acidity. How? Because carbonic acid is formed, which causes the water’s hydrogen ions to dissociate, changing its pH level.

If you add carbon dioxide to a water supply, it’ll make it less alkaline and more acidic. The average pH of tap water is neutral – around 7. Water with high carbon dioxide levels might have a pH of 6.5 or lower.

Carbon dioxide in water

Health Effects Of Carbon Dioxide in Water

Does carbon dioxide in water have any health effects in the human body? Luckily, the answer seems to be no. Carbonic acid is a weak acid that doesn’t pose a health threat if it’s consumed in small amounts.

A recent study found that total capture of carbon dioxide in our global tap water supplies doesn’t appear to be harmful to our health. However, if carbon dioxide decreases water’s pH, this could cause a number of health effects associated with drinking acidic water, like teeth damage, increased likelihood of heavy metals exposure (due to the water’s corrosive properties), and digestive problems.

Environmental Effects Of Carbon Dioxide in Water

If the natural water sources used for drinking water supplies contain too much carbon dioxide, there’s a risk that the fish and other living organisms in the water may be harmed.

Carbon dioxide hinders fish’s ability to transport oxygen in its blood, potentially causing the fish to suffocate – even if the water supply contains a lot of oxygen. Acidity caused by elevated carbon dioxide levels may also damage fish’s gills and restrict their oxygen intake, potentially killing them. Ocean acidification is a major problem caused by CO2.

🤔 What Is Carbon Dioxide?

Carbon dioxide is a gas naturally present in the earth’s atmosphere. This gas is odorless and colorless when it occurs at standard atmospheric pressures and temperatures.

CO2 is formed of one carbon atom (C) and two oxygen atoms (O2).

In the environment, carbon dioxide acts as a “greenhouse gas”, absorbing dangerous infrared energy while allowing visible light to pass. Thanks to carbon dioxide, the earth is able to hold heat from the sun, which is needed for human survival.

However, too much carbon dioxide can have a detrimental effect on the atmosphere, causing the earth to warm up too quickly (global warming).

carbon dioxide in earths atmosphere

🧐 Where Does Carbon Dioxide Come From?

Carbon dioxide is constantly present in the earth’s atmosphere, and has been since the earth was formed. There are two sources of CO2: natural carbon dioxide release and human activities.

Naturally Released CO2

Plants release carbon dioxide when they respirate – and so do animals and humans. When plants and organic compounds decompose, they also release carbon dioxide into the atmosphere. Another natural source of carbon dioxide is volcano eruptions.

Human Activities

Human activities have become a bigger and bigger source of CO2 emissions in the past few centuries. There are tens of human activities that release carbon dioxide into the atmosphere, including the burning of coal, oil, and natural gases, transportation, and cement production.

🚫 How to Remove Carbon Dioxide From Drinking Water

The majority of water filters are unable to remove carbon dioxide. Even reverse osmosis filters, which offer incredibly thorough contaminant removal, can’t remove dissolved gases like CO2.

So, how can you effectively remove carbonic acid from your water?

Neutralizing Filter

Based on our research, the most effective and eco-friendly way to remove carbonic acid from a water supply is to send the water through a tank containing limestone chips, often known as an acid neutralizer or a neutralizing filter.

Limestones are a calcium-rich substance that force water above its natural pH ceiling.

As water passes through the tank, it’ll absorb the minerals in the limestone, neutralizing the carbonic acid, raising pH, and forming calcium bicarbonate.

Magnesium oxide can be used in a similar filter setup to remove carbonic acid as the water’s pH rises. You could also add high pH additives or a pH adjuster to water.

Discover the top-rated acid neutralizer systems for optimal pH balance 👈

Pouring calcite media into the springwell water ph neutralizer

Soda Ash System

You could add a solution of soda ash sodium carbonate to your water for similar results. The water’s carbonic acid reacts with the carbonic acid, forming sodium bicarbonate.

This treatment method is a good option if you don’t want to increase your water hardness or introduce alkaline salts to your water.

Natural Off-Gassing

If you leave water to sit out for long enough, it’ll release dissolved gases like CO2 back into the air. Try leaving your water to stand in a jug overnight. By the morning, its dissolved CO2 content should be lower.

📑 Final Word

Carbon dioxide in drinking water is usually harmless, but high levels of CO2 might put your water in the acidic pH range.

If you’re concerned or curious about your water’s carbon dioxide levels, buy a CO2 water test. Most water filters don’t remove this dissolved gas from water, but you can use a pH neutralizing filter if you’re keen to drink water with a lower CO2 content.

❔ Carbon Dioxide and Tap Water: FAQ

How does carbon dioxide affect the pH of tap water?

Carbon dioxide forms carbonic acid, which makes water acidic. A lower pH in drinking water may be caused by excess carbonic acid. Excessive CO2 may even affect water temperature.

Does tap water absorb CO2?

Yes, tap water absorbs CO2. Water is more likely to absorb CO2 if it’s slightly alkaline (meaning that its natural pH ceiling is higher).

Is it safe to drink carbonated water?

Yes, drinking carbonated water (water with carbon dioxide gas dissolved in it) is safe. There’s no evidence to suggest that this water has health effects. In fact, drinking carbonated water instead of soda or alcohol is beneficial. However, you may experience bloating and gas from drinking fizzy water.

  • Brian Campbell
    President & CEO, CWS, CWR

    Brian Campbell, a WQA Certified Water Specialist (CWS) and Certified Water Treatment Representative (CWR) with 5+ years of experience, helps homeowners navigate the world of water treatment. After honing his skills at Hach Company, he founded his business to empower homeowners with the knowledge and tools to achieve safe, healthy water. Brian's tested countless devices, from simple pitchers to complex systems, helping his readers find the perfect fit for their unique needs.

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