Abstract: A pipe system for supplying liquid fuel to a underground tank from a supply station and for transfer of said fuel from said tank to at least one dispensing station, said system comprising an assembly of flexible inner piping through which the fuel flows and an assembly of flexible outer piping enveloping the inner piping. The assembly of outer piping is continuous and envelops the inner piping along its entire length without interruption between the supply station and the underground tank and/or between said tank and the dispensing station and advantageously with the inner piping centered within the outer piping by means of concentric spacers perforated to allow gasoline leaking thereinto to flow therepast along the thus formed annular spacing, and preferably also with a branch bypass pipe to interconnect the annular spacing of the outlet conduit with the annular spacing of the inlet conduit to allow collection of gasoline leaking into such spacings into a common gravity fed cup.