Improving and managing universal services of water and sanitation in a holistic manner is critical to achieving the Sustainable Development Goals, and addressing the needs of millions of people around the world. Ensuring access to water services is a key factor in working towards the SDGs, and water service delivery planning can support utilities in improving provision of these services. A service delivery plan identifies the actions required and associated costs for achieving a defined level of water services delivery over a defined period of time. This publications is a guideline or how-to manual on preparing water service delivery plans with a focus on small to medium sized organised water utilities having with approximately 5,000 to over 100,000 connections mainly in areas with limited capacity and resources. The manual is simplified enough to ensure that these utilities are able to move from a situation where they are struggling to deliver water services to where basic service levels in terms of water quality, quantity, accessibility, reliability, affordability, and acceptability are met. Meeting these basic service levels provides a strong foundation for the utility to progressively move up the ladder of delivering improved services.

There are 2.4 billion people without improved sanitation and another 2.1 billion with inadequate sanitation (i.e. wastewater drains directly into surface waters), and despite improvements over the past decades, the unsafe management of fecal waste and wastewater continues to present a major risk to public health and the environment (UN, 2016). There is growing interest in low cost sanitation solutions which harness natural systems. However, it can be difficult for wastewater utility managers to understand under what conditions such nature-based solutions (NBS) might be applicable and how best to combine traditional infrastructure, for example an activated sludge treatment plant, with an NBS such as treatment wetlands. There is increasing scientific evidence that treatment systems with designs inspired by nature are highly efficient treatment technologies. The cost-effective design and implementation of ecosystems in wastewater treatment is something that exists and has the potential to be further promoted globally as both a sustainable and practical solution. This book serves as a compilation of technical references, case examples and guidance for applying nature-based solutions for treatment of domestic wastewater, and enables a wide variety of stakeholders to understand the design parameters, removal efficiencies, costs, co-benefits for both people and nature and trade-offs for consideration in their local context. Examples through case studies are from across the globe and provide practical insights into the variety of potentially applicable solutions.

By 2025, two thirds of the world's population will be living in water stressed conditions. Meanwhile, the degradation of water ecosystems is occurring at alarming rates. Water utilities and water regulators that choose to play an active role in catchment management with nature based solutions (NBS) are uniquely positioned to help. Building a robust knowledge base and supporting opportunities for cross-sector collaboration are fundamental to the mainstreaming of NBS. The International Water Association (IWA) and The Nature Conservancy (TNC) are working together to encourage and facilitate active utility involvement in NBS, as well as promoting stronger connections between water utilities and regulatory bodies. Implementation of NBS involves multiple, interdependent stakeholders at various governance levels, and consequently regulators a key role in creating the enabling environments for these interactions and negotiations. This publication taps into diverse geographies and contexts, delving into case studies for a richer conversation that addresses the variety of challenges and elements for success for integrating NBS into water utility operations and planning. By publicizing successful case studies, the IWA/TNC partnership fulfils a dual purpose of endorsing these efforts and providing actionable guidance for other water utilities striving to improve their sustainability and resiliency.