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  • MTBE stands for Methyl tertiary butyl ether or methyl tert-butyl ether and is an additive classified as an oxygenate because it adds oxygen to fuel.

MTBE is a colorless, cancer-linked liquid legally allowed in tap water in all 50 states. Read on to learn more about the dangers of MTBE, how it sneaks into our public water supplies, and the best way to protect yourself from this dangerous hazardous drinking water contaminant.

What is MTBE?

MTBE stands for methyl tertiary butyl ether or methyl tert-butyl ether. For decades, MTBE has been used as a gasoline additive to make cars more fuel-efficient, reduce greenhouse gas emissions, and raise octane levels to improve engine performance. MTBE is an additive classified as an oxygenate because it adds oxygen to fuel. That’s why MTBE is most likely to contaminate water due to gasoline spills or leaks.

What makes MTBE so frightening, and difficult to detect, is its invisibility, longevity, and mobility. Just one spill or leak can secretly contaminate multiple water supplies for years - and even decades. So even though recent use of MTBE is decreasing in an effort to better protect our environment and our water, MTBE contamination can—and will—continue.

  • It’s basically invisible. MTBE is a colorless liquid. Which means you can’t see it in your water - even if you’re looking for it.

  • It can thrive in soil and water for decades. Which means it can continue to pollute the environment, as well as tap water supplies, years after any leak or spill.

  • It’s mobile. It easily mixes with soil and water - and can spread far and fast. This gives the chemical plenty of opportunity to sneak into tap water sources, near and far, like surface water and groundwater.

The bottom line is that MTBE can quickly mix with water or seep into soil, potentially reaching groundwater sources. And once groundwater contamination occurs, MTBE can spread with the flow of the water, contaminating even more soil and public water supplies - even those miles and miles away.

Contamination Facts







The most common ways MTBE sneaks into public water supplies are through gasoline spills or leaks. Here are some specific examples:

  • Storage tank leaks. Gasoline is stored in both aboveground and underground tanks near gas stations, fuel distribution facilities, and industrial sites. These tanks can degrade or develop leaks over time, which allows MTBE to infiltrate surrounding soil and groundwater supplies.

  • Accidental spills and releases. Spills during fuel transport are another common source of MTBE contamination.

  • Contaminated runoff. Because it’s so mobile, rainwater or snowmelt can easily carry MTBE into streams, rivers, drinking water wells, and other bodies of water.

While the U.S. EPA admits that MTBE “likely” causes cancer, the organization does not regulate MTBE in our public water supplies. Therefore, there is no enforceable drinking water standard for MTBE. And it is legally allowed in our public drinking water supplies - at any level.

And since the chemical is not regulated, that means it’s not tested for, either. Which means even if your water is contaminated, you’d probably never know it… nor would your local water treatment center.

Recent data from the Environmental Working Group (EWG) shows that MTBE has been found in public water supplies in at least 27 states, putting millions of Americans at risk. Outbreaks have occurred from coast to coast, from Fallston, Maryland to Santa Monica, California over the past several decades.

To protect public health, the Environmental Working Group (EWG) has established “health guidelines” for drinking water quality and safety. The EWG suggests that no more than 13 parts per billion (ppb) of MTBE should be allowed in water to protect the public from cancer.

For perspective, 13 ppb is basically the equivalent of 13 drops of MTBE mixed into an Olympic-sized swimming pool. In other words, even minimal, near-zero levels of MTBE / concentrations of MTBE can be considered highly dangerous and, according to EWG research, can carry cancer risks.

Meanwhile, EWG data shows some drinking water supplies containing MTBE levels as high as 62.3 ppb. That’s more than 5x what the EWG considers safe for public health!

So not only has MTBE been found in drinking water supplies from coast to coast, it’s also found at alarmingly high doses / high concentrations.

Health Effects of MTBE Exposure

Animal studies have linked ingestion of MTBE through drinking water with the following health effects:

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Remember, the U.S. EPA does not protect Americans from MTBE contamination. Therefore, we must protect ourselves. The problem is, bottled water can be just as dangerous as tap water. Boiling water is risky. And the vast majority of typical, mainstream water filters are not powerful enough to remove the chemical.

All of our premium water filters and filtration systems remove up to 99.9% of MTBE from tap water and private well water, so you can trust every drop. In fact, our filters are the only water filters on the planet proven to protect you from 365+ contaminants, including MTBE, without targeting beneficial minerals!

So if you want proven protection from MTBE and complete confidence in your water, upgrade to Clearly Filtered today to get easy access to clean, safe drinking water!


1. EPA Draft Says MTBE a 'Likely' Cause of Cancer


3. MTBE controversy

4. Fact Sheet: Santa Monica MTBE project

5. ToxFAQsTM for Methyl tert-Butyl Ether (MTBE)

6. Methyl tert-Butyl Ether (MTBE) and Drinking Water

7. ToxGuideTM for Methyl tert- Butyl Ether (MTBE)

8. Global Product Strategy (GPS) Safety Summary: Methyl-tert-Butyl Ether (MTBE)

9. Gordon S. (2003). Human Exposure to Methyl tert-Butyl Ether (MTBE) While Bathing with Contaminated Water.

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