Fuel Ethers and Groundwater

EFOA is committed to continuous promotion of best practices for handling fuel ethers as part of its goal to reduce and prevent contaminations in surface and groundwater.

Background concentrations (= surface water e.g. rivers, lakes)

Widespread use of fuel ethers in gasoline has lead to detectable concentrations in the environment, along with other fuel components, albeit in very small concentrations.  The source of these background levels was the partially burned petrol (white smoke) that occurs when a car is first started and before the catalytic converter is warm enough to work.

The impact of the background concentrations has been analysed intensively in the science based EU-Risk Assessment on MTBE. The Risk Assessment concluded that the measured concentrations of MTBE are far below any threshold where they could pose a possible concern to people’s health. This assessment for MTBE is valid for ETBE and TAME as well.

Despite an increase in the use of fuel ethers in recent years the average background concentration has not increased. It is thought that the steady improvement in car technology (faster warming catalysts) and the introduction of vapour recovery equipment at petrol stations is leading to lower emissions and a decrease of these measured concentrations. Together these will lead to a reduced background concentration of fuel ethers which is already today far below any critical limit.

Groundwater concentrations (= underground water)

Fuel ethers have the potential to impact water used for drinking. The EU-Risk Assessment for MTBE concluded that, although concerns do exist regarding water contamination, the measured concentrations of ethers are far below any threshold where they could pose a possible concern to people’s health. This assessment for MTBE is valid for ETBE and TAME as well.

The EU-Risk assessment for MTBE confirmed a taste and odour threshold of 15 µg/l for MTBE and this limit has been included in water quality regulations in several EU Member States.  

Further reading
Code of Best Practice for handling fuel ethers