Small-scale water supply and sanitation systems form an essential part of the provision of services in the pan-European region, particularly in rural areas, and sufficient financial means are required to facilitate their safe operation and safeguard public health. Challenges for these systems include a large financial gap between the costs of providing services and availability of funding sources, insufficiency in ability to cover all recurrent costs, low economies of scale and lower policy attention and financial priority from governments. This publication guides national and subnational policy-makers responsible for water and sanitation interventions in defining strategies for the sustainable financing of service provision through small-scale water supply and sanitation systems.