# High Rate Stormwater Treatment for Water Reuse and Conservation--Review
## 1 Introduction  
Green Stormwater Infrastructure (GSI) provides a sustainable framework for stormwater harvesting, employing methods like vegetated swales, constructed wetlands, biofilters, etc. These approaches offer multiple advantages, including flood mitigation, water quality improvement, and support for urban ecological systems. GSI is variously referred to in some countries as low-impact development (LID), water-sensitive urban design (WSUD), and sustainable urban drainage design (SUDS). GSI supports the development of cities with diverse water sources and minimal energy reliance, promoting broader social, political, and environmental sustainability. The effects of GSI on urban ecology, public health, and sustainability--both immediate and long-term--are outlined in Table 1. This review focuses primarily on the technical aspects of stormwater reuse. Legal and regulatory considerationsare addressed by national water quality guidelines specific to the intended use of the water and are not discussed in detail here. For instance, in Australia, drinking water standards are outlined in the Australian Drinking Water Guidelines [1], while the Australian Guidelines for Water Recycling [2] provide a framework for developing safe and sustainable strategies for recycling water from sources such as greywater and stormwater. Stormwater management is a critical component of water quality efforts at the catchment, waterway, and local levels. The Australian Guidelines for Urban Stormwater Management [3] promote an ecologically sustainable approach to managing stormwater. Similar documents addressing these issues exist in other countries applicable in their jurisdictions. Among GSI methods, constructed wetlands and biofiltration systems excel in the treatment of stormwater because of other pollutant removal efficiency and suitability for urban areas. However, achieving disinfection levels that meet potable standards, particularly through UV treatment, necessitates effective pre-treatment to reduce pathogen levels. While wetlands and biofilters provide robust pre-treatment, consistent maintenance is key to maintaining their performance over time. The increasing concern about emerging contaminants and microplastics in stormwater and their fate and impacts on human and environmental health is another aspect of GSIs. Ongoing maintenance is essential for the reliable operation of stormwater harvesting systems. Without it, blockages may reduce system efficiency and allow pollutants to re-enter the water supply. Regular vegetation management in wetlands and biofilters also helps maintain treatment capacity. A thorough life cycle cost analysis should account for aspects such as planning, design, construction costs, maintenance schedules, pollutant disposal, de-silting of storage areas, corrective measures, and eventual decommissioning. This comprehensive analysis is vital during the planning stages to balance treatment costs with environmental benefits. GSI offers valuable benefits for ecological, human, and environmental health and sustainability in both the short and long term. However, the success of GSI systems relies on thoughtful design, regular maintenance, and integration with other urban infrastructure. Adaptive management and ongoing monitoring are necessary to ensure that GSI systems meet evolving needs and continue to deliver desired outcomes as conditions shift. The paper outlines the following main objectives for advancing stormwater management practices: