Efficiency of environmental resources is one of the goals of the sustainable development of a building and its sanitation. Sanitation efficiency was sought through hybrid offsite system, which was a decentralization of sanitation services. This study proposed a hybrid onsite system combining phytoarchitecture and phytosanitation, which empowers renewable building plants to improve resource efficiency, as well as sustainable building environmental health. Based on various empirical studies on sanitation management in rural and urban areas in many places, this retrospective study identified three wastewater disposal efficiencies. It was through quantity distribution, environmental media in which the greywater could be discharged, and quality treatment. The results marked the feasibility of wastewater services for greywater treatment, which served at least 75% of the wastewater quantity. Its main contribution was related to the distribution of discharge to all environmental media, and the improvement of the quality of greywater at its disposal. Building plants could be used for hybrid onsite system, thereby making these plants multifunctional to maintain the quality of the building environment. This hybrid onsite phytosanitation system covered various feasibility features compared to other existing systems. Implementation was flexible for new provisions and adaptation to existing systems for both urban and rural areas. Thus, the service maintained sustainable buildings and environmental health.