In order to do a life cycle assessment (LCA) of a waste water treatment technique, a system to handle the mapped inventory data and a life cycle impact assessment (LCIA) method/model is needed. Besides NEPTUNE, another EU-funded project has the same methodology need namely INNOWATECH (contract No. 036882) running in parallel with NEPTUNE but focusing on industrial waste water. With the aim of facilitating cooperation between the two projects a common LCA methodology framework has been worked out and is described in the following. This methodology work has been done as a joint effort between NEPTUNE WP4 and INNOWATECH WP4 represented by the WP4 lead partner IVL. The aim of the co-operation is to establish common methodologies and/or LCA models and/or tools in order to achieve a homogenous approach in INNOWATECH and NEPTUNE. Further, the aim is to facilitate possibilities of data exchange between the two projects and eventually normalise the final output. A coordination/working group with representatives from INNOWATECH (WP4) and NEPTUNE (WP4) has been set up. It consists of the following representatives from the two projects: NEPTUNE: Henrik Fred Larsen (DTU/IPU), Michael Hauschild (DTU), Henrik Wenzel (SDU). INNOWATECH: Mats Almemark (IVL), Christian Junestedt (IVL). In support of this work and as a starting point for especially NEPTUNE WP4, a review of existing LCA studies on waste water treatment technologies has been done by DTU and is included as an Appendix.