Water utilities use a variety of well-tested and reliable treatment processes to recycle / reclaim water. Utilities generally describe the various stages of treatment rather than the technologies utilized when referring to water quality, as there are multiple treatment techniques for achieving essentially the same result.
Generally speaking, the four core stages of treatment are primary treatment, secondary treatment, tertiary or advanced treatment, and disinfection. The number of treatment steps will vary based on how the water will be used. Most recycled water, however, will undergo some form of disinfection.