Water is considered a vital resource for global sustainability and economic growth. Nevertheless, global climate change, rapid urbanization, and environmental degradation are accelerating the depletion of clean water resources at an alarming pace in the twenty-first century. In response, Rainwater Harvesting Systems (RWHS) emerge as a promising alternative water source.

Malaysia, endowed with high annual rainfall and substantial domestic water consumption stands poised to leverage rainwater harvesting for both potable and non-potable uses. Yet, the efficacy of harvested rainwater hinges on meeting acceptable water quality standards. The quality of harvested and stored rainwater can be influenced by topography, weather, and sources of pollution. Therefore, treatment and regular monitoring are required as poor water quality can impose health risks due to the existence of chemical, physical and microbiological contaminants. With the RWHS treatment system, the harvested rainwater can be converted into clean water as an alternative water supply for various domestic applications.

Calculate the water efficiency of REDAC building using WE Calculator developed by Greenbuildingindex Sdn. Bhd. based on the rainfall station located at Simpang Empat station. Propose possible solutions in brief to improve the water efficiency. Submit the calculations and proposed solutions in a proposal.

Subsequently, present solutions for both potable and non-potable water reuse for building occupants, complete with treatment technologies and schematic layouts, with the goal of advocating rainwater reuse as a comprehensive strategy for efficient water management and safety.

Propose a sustainable solution of rainwater harvesting and storage with minimum cost which fulfill the total coliform requirement in Water Reuse Standard in Malaysia (http://www.nahrim.gov.my/). Prepare the proposal according to the guidelines.