There is currently a shift of emphasis in the approach to treatment of landfill gas and leachate. Until recently, there have been two disparate schools of thought concerning the collection and disposal of these two by-products of organic waste degradation within the same bio-reactor. The tendency in the past has been to study gas and leachate as separate problems each of which requiring a separate solution. The reality is that both gas and leachate are consequences of the same processes within landfill sites, and are merely different phases from a common source. The optimum approach would logically appear to be treatment of both gas and leachate within the same system and attended to during the same equipment installation phase. Indeed, following the tenets provided for by the BATNEEC (Best Available Technology Not Entailing Excessive Cost) notes this would appear to be the preferred option, in terms of ease of installation, long term maintenance and, perhaps most importantly in the present climate, cost. As far as prediction of potential production and end treatment solutions is concerned, leachate and landfill gas can be treated as discrete by-products of degradation. However, the testing of theoretical models of production rates, as well as spatial location within a collection network, can be treated together. Technological improvement, and the continued downward trend in material costs allow those who specify systems, and those who buy them, a wealth of options for the safe combined disposal of both landfill gas and leachate.