Abstract: In a leak testing and leak localization arrangement for leak testing and localization for flat roofs or the like which are sealed by at least one electrically insulating sealing web (6), at least one voltage source (12) is applied between an upper side of the sealing web and below an underside of the sealing web. The upper side of the sealing web is sampled by means of a measuring device (9) provided with two measurement sensors (10, 11). In order to achieve reliable leak testing and precise leak localization with contact being made in an uncomplicated manner with the voltage source (12), web-shaped electrically conductive material is arranged on the underside of the sealing web (6) and is connected to one terminal of the voltage source (12). For this purpose, at least one metal grating web is provided as the web-shaped electrically conductive material, which web can be laid easily and is non-combustible and durable.