The Author describes the need for and the technical development of a new, advantageous, system for the detection of leaks beneath waste disposal linings. The paper sets this technical development within the context of other similar approaches to the problem of leak detection. Essentially, the system comprises the use of cross-laid textiles, containing conductor wires, and separated by an electrically insulating textile layer. This ‘sandwich’ is placed below the prime impermeable membrane. Leaks are detected by measuring both conductivity and capacitance characteristics between pairs of adjacent wires as well as between overlying wire sets: This complex approach allows the inherent variables of liquid quantity and conductivity to be differentiated and leak locations identified to within half a metre. The system permits rapid and economic repair of leaking membranes, even after a waste disposal site might be full and landscaped, without the need for excavation. Naturally, the system can also be used for construction monitoring of joint efficiency during fabrication and commissioning. The paper describes the successful outcome of large scale trials.