The Swedish Defence Research Agency (FOI) has addressed challenges related to environmental impact and sustainability of temporary communities such as the military, peacekeepers, or humanitarians in conflict and disaster areas in approximately 20 years. Experience has shown that the environmental legacy of these communities, regardless of purpose and type, may be significant, especially regarding the cumulative (or aggregate) impact. For instance, the total water footprint of all the actors present in an area, together with the local population, may exceed an aquifer's natural recharge rate, causing irreparable damage to the local environment. Direct, second- or third-order impacts are counter to resiliencebuilding efforts and hampers positive development in the affected region. The report was originally produced as a paper within the project Environmental Dimensions of Sustainable Recovery: Learning from Post-Conflict and Disaster Response, led by the American University´s School of International Service and World Wildlife Fund, 2012-2014. It presents the result discusses FOI's experiences with environmental issues at both the policy level and the tactical level, with and within the military community, UN peacekeeping and the humanitarian community operating in conflict and/or crises areas. It discusses some available tools to predict and manage environmental impact and suggests ways to achieve a greater flow of information among the different actors present over time in an area of operation.