In industrialised countries water service providers (WSPs) must provide an appropriate level of service with an acceptable performance at an acceptable cost to customers. In the UK a move towards sustainable development is now also a major goal for WSPs. However, the imposition of institutional systems and regulatory targets still encourage the adoption of less sustainable technologies or solutions by the water industry. It is within this context, that the Sustainable Water industry Asset Resource Decisions (SWARD) project has developed a set of decision support processes that allow WSPs to assess the relative sustainability of water/wastewater system asset development decisions. A Guidebook has been produced that takes the WSP and its stakeholders through the processes essential to incorporating sustainability in asset investment decision-making. Several case studies that demonstrate the SWARD principles in application are included within the Guidebook, the experience of which is described in this paper.