Waternet, the water cycle company of Amsterdam and surrounding areas, uses the life cycle assessment (LCA) method to evaluate the environmental impact of investment decisions and to determine the potential reduction of direct and indirect greenhouse gas (GHG) emissions of different alternatives. This approach enables Waternet to fulfil its corporate objective to improve sustainability and to become climate neutral by 2020. Three example studies that give a good overview of the use of LCAs at Waternet and problems encountered are discussed: phosphate removal and recovery from wastewater, pH correction of drinking water with carbon dioxide (CO2) and materials for drinking water distribution pipes. The environmental impact assessments were performed in SimaPro 7 using the ReCiPe method and the Intergovernmental Panel on Climate Change Global Warming Potential (IPCC GWP) 100a method. The Ecoinvent 2.0 and 2.2 databases were used for the material and process data. From the examples described, it can be concluded that only the phosphate removal case had a significant effect on the climate footprint. The article discusses applications and limitations of the LCA technique. The most important limitation is that the impact of water consumption and the possible impact of effluent compounds to surface water are not considered within the used methods.