In Singapore, not a single drop of water is wasted.

Singapore lacks deep springs and aquifers: its terrain is flat and low-lying, so the conditions for creating natural water sources are lacking. Yet the Asian metropolis has become a unique model worldwide for its ability to waste not a single drop of water and never, not even for a single day, find itself in a water crisis. Unlike entire areas, such as southern Italy, where natural water exists but is wasted, water recycling does not exist, and water shortages (with entire communities left without water), especially during periods of drought, are very frequent.

Singapore's winning bet hinges entirely on one word: recycling, both of rainwater and wastewater.

As far as rainwater is concerned, Singapore is organised with a huge collection system, with about two-thirds of the territory that act as a catchment area. Rainwater that falls on rooftops, streets, parks, and urban areas is channeled (via highly advanced and sophisticated systems, into canals and artificial rivers) to 17 harvest basins, some of which are artificial lakes, others located in the city center. From there, the rainwater flows into water purification plants, is treated with processes that involve both filtration and disinfection, and then reaches residents' taps.

During specific periods, when there is drought and the demand for water is very high, the water stored in rainwater collection basins is supplemented with water coming from desalination plants. In this case, Singapore uses almost exclusively reverse osmosis desalination (RO), today the most advanced world standard, which works with three steps:

• Collecting water from the sea
• Elimination of impurities and removal, through grids and filters, of algae, sand and debris
• Transformation into drinking water, through a remineralization process (for taste and chemical characteristics), disinfected and made compliant with total safety standards.

A final piece of the puzzle that allows Singapore, despite lacking aquifers and springs, to always have abundant drinking water, is the importation of drinking water, in cases of emergency, from Malaysia.

As for waste water, the system of advanced recycling and reuse which transforms them into a precious and safe resource is the program NEW Water, managed by the National Water Agency PUB (Public Utilities Board), within the broader strategy of the Four National Taps ("four national taps"): rainwater harvesting, desalination, imported water, wastewater recycling. With the NEWater system, water passes through very fine membranes that filter particles, bacteria, and suspended solids, and a semi-permeable membrane removes salts, viruses, pesticides, heavy metals, and many other impurities.

Finally, an ultraviolet (UV) disinfection eliminates any remaining traces of microorganisms, ensuring microbiological safety and the final result is ultra-clean water, which exceeds international drinkability standards such as those of the World Health Organization (WHO) and the United States Environmental Protection Agency (USEP).

Currently, a significant portion of water demand is met by NEWater, and there are plans to make it an even more significant source in the future. Some official documents indicate that in the past up to about 40 percent of water needsof the island could be satisfied with NEWater, with plans to reach over 50 percent in the next few years.

Thanks to the four taps of the  Four National Taps (rainwater harvesting, desalination, imported water, wastewater recycling), Singapore is considered a sponge city, the only one in the world where not even a drop of water is wasted.