• the technical, institutional, and financial capacity to satisfy public health and safety requirements on a long-term basis.

Like any good business, a sustainable water system can also adapt to future changes in regulatory requirements and customer demand.

Sustainability depends not only on a system's capacity and capabilities, or on its financial prospects, but also on the larger socioeconomic and resource environment that both supports and draws on the system, the regulatory requirements the system must meet, and the technical and financial assistance available to it. A thorough evaluation of all these factors (including the system's own resources) is necessary to identify the main deficiencies jeopardizing sustainability. Water systems need to periodically evaluate their present and future plans, processes, skills, and services and seek to identify options and solutions that will promote sustainability. The ability to effectively implement such potential solutions, and to identify and implement them in the future, is an oft-overlooked but critical component of a system's sustainability. Achieving sustainability is not a one-time task; it requires a continuous effort.

Small systems today face severe challenges, including rapidly increasing regulation, declining water quality and quantity, legal liability for failing to meet the SDWA or other purveyor responsibilities, financial distress, and customer resistance. A system's ability to deal with these challenges depends to a great degree on its managerial, technical, and financial capabilities. Many systems possess adequate staff, expertise, and other resources to meet these challenges, or they can develop the necessary resources. Systems that lack these assets or the ability to develop them, or that simply face community, socioeconomic, or environmental issues beyond their control, usually need to be restructured—that is, absorbed into, combined with, or served by other utilities.

Communities require water of sufficient quality and quantity to meet their needs, reliably delivered at affordable rates. A small water system's ability to meet these basic expectations often depends on factors beyond the system's control.

The most obvious such factor is a lack of sufficient community income to maintain the water system's infrastructure and operations. As discussed in Chapter 2, many small rural systems suffer from this problem.

Another factor is the stability of the community's population. If a system's population is continually decreasing, as in many rural communities, or rapidly increasing, as in many periurban areas, the system often lacks the expertise or