Sewage treatment plants (STPs) can be considered as factories for the production of water, nutrients, energy, among other resources, and the final effluent quality is determined by the technological route adopted and the operating practices. It is in these units that the standards for discharge of treated sewage into water bodies or reuse (urban, agricultural, industrial, among others) are achieved. Despite the enormous potential, there are few full-scale experiences. The absence of a more comprehensive and specific national legislation for reuse is one of the biggest obstacles to its dissemination. This technical note (TN), the first of the collection “Non-potable water reuse: legal aspects, urban and agricultural use, and emerging technologies for the production of water for reuse”, presents the topics of interest related to legal aspects, agricultural use, gray water treated in constructed wetlands, high rate algal ponds, aerobic granular sludge, dynamic membranes post UASB reactor and systems with support medium based on polyurethane foam post UASB reactor. With the information contained in this collection of TNs, it is expected to contribute to the dissemination of consolidated knowledge by experts and sanitation service providers, and technical-scientific production applied to the subject of sewage treatment and water reuse.