[Rabble]

"How could it get into groundwater unless the underground gas tanks were leaking?

Not certain of this but - I believe that MTBE when burned with gasoline becomes airborne and when rain washes it to the ground it seeps in, resulting in groundwater pollution.

[SpaceBar]

My understanding was that it was dispersed as a product of combustion and rained down as mentioned, but leaking underground storage tanks (called LUST in the hazmat/envirolaw industry) are possibly to blame as well.

[redgolum]

No, it is from leaking tanks.

MTBE burns pretty much completely. The main complaint comes from that it makes well water smell like dead fish (beside the carcinogen aspect).