Abstract: This invention relates to liquid leak detectors and detection systems. A liquid leak detector (10) includes a first electrically conducting layer (12), a second perforate, open, porous and/or permeable electrically conducting layer (13) opposed to said first layer and an intermediate perforate, open, porous and/or permeable electrically non-conducting layer (14) for electrically isolating the two conducting layers (12, 13) whilst allowing liquid, which passes through the second conductor (13), to form an electrically conducting path between the conductors (12, 13).