An overall analysis of several permeable reactive barriers (PRBs) which have been in operation at manufactured gas plants (MGPs) and related sites for over five years has been implemented. It was found that virtually all of them are performing well, or even perfectly, over time. Especially in Europe, 'efficiently controllable' PRBs (EC-PRBs), packed with granular activated carbon (GAC) to treat polycyclic aromatic hydrocarbons (PAHs) and benzene, toluene, ethylbenzene and xylenes (BTEX), have successfully been operated for over five years. This contribution covers the main results. Major overall conclusions from the work of the German PRB research and development (R&D) network 'RUBIN', and from the work in the recently published French, UK and German PRB handbooks and guidelines are included. In Europe, EC-PRBs such as in situ vessels (ISV) or modified F&G technologies ('non-classical' F&G) are the preferred solutions, in comparison to continuous reactive barriers (CRBs) in the US. The criteria supporting the first technological option are that the PRB can be configured to suit site-specific features, and that monitoring and maintenance can be controlled more effectively. Some companies propose a maintenance strategy based on annual operations that can range from simple clearing of clogged sections to replacement of the reactive medium (particularly recommended for barriers based on the adsorption principle). This approach can only be considered if the design of the barrier allows easy access to the treatment reactor and is sometimes backed up by guarantees on the performance of the barrier, usually over periods of 10 or 30 years. Although the PRB concept first emerged in North America, our study shows that European projects have also played a part in the development of this technology. After projects in 1994 (A22 motorway, France) and 1995 (Belfast, UK), the technique was developed in 1996 and began to take off in 1998 (first PRBs in Germany), however with a focus on zero valent iron (ZVI) PRBs to treat chlorinated volatile organic hydrocarbons (cVOC). Nevertheless, it must be stressed that, despite the fact that PRBs at former MGPs employing GAC to treat PAHs, BTEX, cyanides etc. represent a minority of all PRBs (around 10% of approximately 120 PRB sites worldwide), they have constantly performed well over time, in comparison to a considerable number of ZVI barriers at cVOC sites, which did not. Hence, EC-PRBs packed with GAC seem to have a bright future for application at numerous MGPs worldwide, especially in Europe.