Fresh water supply system for an aircraft

A fresh water supply system in an aircraft, comprising at least one fresh water supply tank, water tap means in said aircraft, main line means connecting said water tap means to said supply tank, said main line means being installed at a substantially horizontal level in said aircraft, said water supply tank being positioned substantially at the same horizontal level, at least one water conveying means connected to said system for transporting fresh water from said supply tank to said water tap, said main line means having at least one section formed as a ring conduit (3) having a horizontal length and at least one tap branch line (4) connecting said water tap means to said ring conduit, said water conveying means maintaining a water circulation in said ring conduit, said system further comprising heating means connected only to a portion of said ring conduit, said portion of said ring conduit having a short length relative to said horizontal length of said ring conduit, said system further comprising a heat insulation (10) provided on at least a portion of said ring conduit, said heat insulation in combination with said circulation optimally reducing said short length so that freeze-up is avoided with an optimally low heating energy input.