Plumbing systems have evolved from being a simple means of distributing water and collecting wastes into increasingly sophisticated systems that must also address environmental concerns. The design of a plumbing system must incorporate not only traditional issues of sanitation, flow, and pressure, but also environmentally based preferences for recycling wastewater, use of non-utility water, and different treatments for potable and non-potable water. New technologies, responses to water efficiency concerns, and community-based water quality goals pose numerous challenges for 21st Century plumbing design. These challenges are often exacerbated by stresses induced by rapid development.
"Non-utility" water refers to water not provided by the utility, such as rainwater and graywater.