1. Water recycling
2. Desalination
3. OTEC (Ocean Thermal Energy Conversion)
Water Recycling Water recycling here on Oahu is an important part of ensuring a sustainable water supply for future generations. Through the natural water cycle, the earth has recycled and reused water for millions of years. Water recycling generally refers to projects that use technology to speed up these natural processes. Recycled water can reduce much of Oahu's aquifer water demands, as long as it is adequately treated to ensure water quality appropriate for the use. The recycling of water has many benefits. The main benefit is that by recycling water, we are saving ground water for other uses. Another benefit is that recycled water is safe and has been used for over 40 years, with no negative human or environmental side effects (HWRF). Because the amount of precipitation on Oahu changes varies, sometimes the island goes through drought. With water recycling, the amount of secondary effluent available for recycling is always greater than the demand of it, therefore making it virtually drought proof. Also, recycled water can be produced at a price that is cost-effective, when compared with other methods. Water recycling facilities on Oahu have been in place since 2000 (HBWS). The Honouliuli Water Recycling Facility in Eva, is the largest recycling plant on Oahu. The plant was built next to the City and County of Honolulu's waster water treatment plant, which provides the recycling plant with secondary effluent as the base for the recycling process. Currently, the facility has the production capacity of 12 million gallons per day and produces two grades of recycled water. R-1 water is used