▁for ▁the ▁environment , ▁but ▁it ▁im parts ▁an ▁un ple asant ▁taste ▁to ▁water ▁even ▁at ▁very ▁low ▁concentr ations . ▁The ▁maximum ▁cont amin ant ▁level ▁of ▁M T BE ▁in ▁drink ing ▁water ▁has ▁not ▁yet ▁been ▁established ▁by ▁the ▁United ▁States ▁Environment al ▁Prote ction ▁Agency ▁( E PA ). ▁The ▁leak age ▁problem ▁is ▁partially ▁attributed ▁to ▁the ▁lack ▁of ▁effective ▁reg ulations ▁for ▁under ground ▁storage ▁t anks , ▁but ▁sp ill age ▁from ▁over fill ing ▁is ▁also ▁a ▁contrib utor . ▁As ▁an ▁ing red ient ▁in ▁un le aded ▁gas oline , ▁M T BE ▁is ▁the ▁most ▁water - sol ub le ▁component . ▁When ▁dissol ved ▁in ▁ground water , ▁M T BE ▁will ▁lead ▁the ▁cont amin ant ▁pl ume ▁with ▁the ▁remaining ▁components ▁such ▁as ▁ben z ene ▁and ▁to lu ene ▁following . ▁Thus ▁the ▁discovery ▁of ▁M T BE ▁in ▁public ▁ground water ▁well s ▁indicates ▁that ▁the ▁cont amin ant ▁source ▁was ▁a ▁gas oline ▁release . ▁Its ▁criticism ▁and ▁subsequent ▁decre ased ▁usage , ▁some ▁claim , ▁is ▁more ▁a ▁product ▁of ▁its ▁easy ▁detect ability ▁( t aste ) ▁in ▁extremely ▁low ▁concentr ations ▁( pp b ) ▁than ▁its ▁to x icity . ▁The ▁M T BE ▁concentr ations ▁used ▁in ▁the ▁EU ▁( us ually ▁ 1 . 0 – 1 . 6 %) ▁and ▁allowed ▁( maxim um ▁ 5 %) ▁in ▁Europe ▁are ▁lower ▁than ▁in ▁California . ▁ ▁Che v