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Q: What could go wrong if carbon dioxide leaks into my water?

A: Adding carbon dioxide to water does not make it unsafe to drink. CO2 bubbled into water is a beverage: club soda. In the Perrier region of France and other places where CO2 naturally mixes with water, it is bottled and sold.

 

Besides making water bubbly, when CO2 mixes with water a small percentage of the CO2 dissolves and forms a weak acid called carbonic acid. You can taste this acid as the tang in carbonated drinks.

 

However, this is only part of the story. When CO2 and water are in an aquifer, they interact with the minerals that make up the aquifer rock. Some rocks contain minerals called carbonates. These carbonates dissolve quickly in acidic water.

 

Rocks are made up of many different chemical compounds, so when the carbonate minerals dissolve, other compounds also dissolve. When studying the risks of carbon dioxide leaking into water, it’s important to determine what these compounds are, and if they could be released in amounts large enough to degrade water quality.

 

Protection of underground sources of drinking water is the most important objective of the US EPA Underground Injection Control Program that regulates all underground injection in the US, and has been doing so for the last 40 years. [See FAQ What Would a CO2 Leak from an Industrial Site Look Like?] In order to develop the most effective regulations, researchers are studying the effects of carbon dioxide leaks in many ways: lab experiments, field controlled releases, and investigations in places where carbon dioxide is naturally concentrated or released from the earth. [See FAQ Does CO2 leak naturally from the earth?]

 

So far, these investigations are converging on similar results. They show that while carbon dioxide reacts with typical aquifer rocks, the changes in the concentrations of compounds dissolved in the water remain small, similar to natural variation in water composition, and they are temporary.

 


Dr. Changbing Yang of the Gulf Coast Carbon Center approved this FAQ.

 

 

Fact Checked

The link at the left is a summary of changes in the chemistry of shallow groundwater from CO2 injection at the ZERT field site in Bozeman, Montana.

 

 

Fact Checked

Click on the icon at the left to link to the Underground Injection Control Program that regulates all underground storage.

 

 

Fact Checked

This link takes you to a scientific journal article about rock-water-carbon dioxide batch experiments.

 

 

Fact Checked

The link at the left takes you to an article about a push-pull experiment in Cranfield, MS.

 

 

Fact Checked

Click the icon at left to read about a field experiment in which carbon dioxide was released into groundwater under controlled conditions, and the changes in metals were monitored.

 

 

Fact Checked

Click the link at left for a scientific journal article about a computer simulations that were performed to assesses the risk of releasing metals as a result of CO2 injection.

 

 

Fact Checked

The link at the left leads to a computer simulation study of the risks of lead and arsenic from CO2 injection. The authors found that across a range of 38,000 simulation scenarios, the maximum permitted concentration for lead in drinking water was never exceeded, and for arsenic it was exceeded in a few cases.

 

 

Fact Checked

The scientific journal article linked to at the left is a study of the risks to human health from the injection of CO2 underground.

 

 

Fact Checked

The link at the left leads to a study of a location where carbon dioxide naturally bubbles into an aquifer, but the metal contamination is unrelated to the CO2. Rather, the source of the contamination is brackish water that also feeds into the aquifer.