Singapore's NEWater is one of the most documented water recycling programmes operating at national scale. First introduced in 2003, the process takes treated used water (effluent from conventional wastewater treatment) and subjects it to three additional advanced purification stages. The result is high-grade reclaimed water that consistently surpasses drinking water standards set by the World Health Organization and the United States Environmental Protection Agency.
As of 2025, NEWater supplies approximately 40% of Singapore's total water demand. PUB, the national water agency, operates five NEWater facilities with combined capacity exceeding 200 million gallons per day (mgd).
Stage 1: Microfiltration and Ultrafiltration
The first barrier in the NEWater process forces treated used water through hollow-fibre membranes with pore sizes of approximately 0.04 to 0.1 micrometres. At this scale, suspended solids, colloidal particles, bacteria and some larger viruses are physically removed from the water stream.
Modern NEWater plants increasingly adopt Membrane Bioreactor (MBR) technology, which integrates biological treatment with membrane filtration in a single step. MBR systems reduce the physical footprint of treatment facilities, a significant consideration on an island where usable land is limited to 728 square kilometres.
Stage 2: Reverse Osmosis
Water passing through microfiltration enters reverse osmosis (RO) units, where it is pressurised against semi-permeable membranes with far tighter pore structures. RO removes dissolved salts, organic molecules, heavy metals, pesticide residues and virtually all remaining microbiological contaminants.
The resulting permeate is essentially demineralised water. At Bedok NEWater Factory, the RO systems operate in parallel arrays of 16-inch membrane tubes, each containing tightly wound spiral membranes that maximise surface area within a compact housing.
Stage 3: Ultraviolet Disinfection
As a final safety barrier, the RO permeate passes through ultraviolet irradiation chambers. UV light at 254 nanometres wavelength damages the DNA of any remaining microorganisms, rendering them unable to reproduce. Following UV treatment, alkaline chemicals (typically lime or sodium hydroxide) are added to restore the pH balance to neutral levels suitable for consumption or industrial use.
Current Facilities and Expansion
Singapore currently operates the following NEWater plants:
- Bedok NEWater Factory — operational since 2003, the original demonstration-scale plant
- Kranji NEWater Factory — operational since 2003
- Ulu Pandan NEWater Factory — commissioned in 2007
- Changi NEWater Factory (Phase 1) — operational within the Changi Water Reclamation Plant
- Tuas NEWater Factory (TNF) — initial capacity of 25 mgd, with expansion tenders for 75 mgd total capacity launched in late 2024
PUB's expansion roadmap includes reconstruction of the Kranji Water Reclamation Plant and its associated NEWater factory, along with further expansion of the Changi Water Reclamation Plant. These projects are part of a long-term strategy to meet water demand projected to nearly double by 2065.
Quality Assurance and Monitoring
NEWater undergoes over 300 water quality tests at multiple stages of production. These tests cover physical, chemical, biological and radiological parameters. PUB publishes regular water quality reports confirming compliance with both Singapore's own Environmental Public Health (Water Suitable for Drinking) Regulations and international benchmarks from WHO and US EPA.
NEWater has been tested to meet and exceed WHO and US EPA drinking water standards across all measured parameters since production began in 2003.
Membrane Research and Innovation
The Singapore Membrane Consortium (SG MEM) coordinates ongoing research to reduce the energy cost of membrane-based water treatment. Key research areas at NTU's Singapore Membrane Technology Centre (SMTC) include:
- Biomimetic membranes inspired by natural water channel proteins (aquaporins)
- Forward osmosis and pressure-retarded osmosis for energy recovery
- Low-pressure nanofiltration as a less energy-intensive alternative to conventional RO
- 3D-printed spacers that optimise flow distribution within membrane modules
- Advanced fouling detection sensors to extend membrane lifespan
These research lines feed directly into PUB's procurement pipeline, with pilot results from lab-scale membranes tested at operational NEWater facilities before broader deployment.