Summary of Singapore's Water Reuse Guideline or Regulation for Potable Water Reuse
This page is part of the EPA’s REUSExplorer tool, which summarizes the different state level regulations or guidelines for water reuse for a variety of sources and end-uses.
The source water for this summary is Treated Municipal Wastewater.
On this page:
- Technical basis
- Types of planned potable reuse approved for use in Singapore
- Water reuse treatment category/type
- Additional context and definitions
- Potable water reuse specifications (table)
- Upcoming regulations
- References
- Disclaimer
This page is a summary of the country’s water reuse law or policy and is provided for informational purposes only. Please always refer to the country for the most accurate and updated information.
In Singapore, potable water reuseThe use of highly treated recycled water for drinking water purposes. Includes the introduction of recycled water into an environmental buffer, such as groundwater aquifer or surface reservoir being withdrawn for potable purposes (indirect potable reuse), and the introduction of recycled water into a drinking water treatment facility or directly into a potable water distribution system (direct potable reuse). applications include indirect potable reuse (surface water augmentation and groundwater injection). The source of water treated municipal wastewater Treated wastewater effluent discharged from a centralized wastewater treatment plant of any size. Other terms referring to this source of water include domestic wastewater, treated wastewater effluent, reclaimed water, and treated sewage. is specified by the country as treated wastewater. The write-up on this page uses the country’s terms when discussing sources or uses of water that may differ from the Regulations and End-Use Specifications Explorer's (REUSExplorer's) terms.
Technical basis
Singapore allows the use of treated municipal wastewater for indirect potable reuse applications (surface water augmentation and ground water injection) through their advanced treatment process branded “NEWater” (PUB, 2022). The NEWater process generates advanced treated water through three treatment stages: 1) microfiltration/ultrafiltration, 2) reverse osmosis and 3) ultraviolet (UV) disinfection.
NEWater, Singapore’s advanced treated water, is subject to rigorous audit processes annually, conducted by local and international multidisciplinary experts. While not regulated as a drinking water supply, NEWater complies with the Singapore Food Agency’s regulations for drinking water quality according to the 2019 Environmental Public Health Regulations (Water Suitable for Drinking) (Singapore Statutes Online, 2023). NEWater quality is also benchmarked against the 2014 U.S. EPA National Primary Drinking Water Regulations and the 2022 WHO Guidelines for Drinking Water Quality (WHO, 2022).
Source control, primary and secondary treatment upstream play a key role in the quality of the water received at NEWater treatment plants to minimize fouling of the treatment membranes, and to safeguard the quality of NEWater. For example, Singapore uses online sensors for the detection of volatile organic compounds (VOC) in wastewater networks, as an early warning system of illegal discharges of industrial chemicals, spent oils or solvents. These tools aim to help Singapore’s Public Utilities Board (PUB) – Singapore’s National Water Agency – enforce source control of pollutants (WHO, 2017a). A small percentage of NEWater is added to reservoirs where it is mixed with the raw water, before receiving additional treatment at conventional drinking water treatment plants and piped to customers (PUB, 2022).Prior to being distributed or added to reservoirs, NEWater is stored in tanks with a minimum retention time of nine hours to allow sufficient time to respond to contamination or disruptive events while being continuously monitored online (WHO, 2017a).
Both NEWater and potable water in Singapore must meet all applicable requirements for chemical and microbial contaminants stipulated by local and international drinking water standards and guidelines such as the World Health Organization (WHO) guidelines for drinking-water quality (WHO, 2022). NEWater specifications for indirect potable reuse are summarized in the potable water reuse specifications table. Lastly, NEWater is further tested for other chemical and microbial parameters including pharmaceutical and personal care products, endocrine disrupting compounds, industrial solvents and waterborne pathogens. In total, NEWater is tested for f about 300 parameters at frequencies ranging from weekly to annually (PUB, personal communication, November 16, 2023). The technical basis for developing the specifications and/or removal of microbial contaminants, chemicals and other relevant indicators is aligned with international advanced water reuse standards and guidelines such as the WHO potable reuse guidance (WHO, 2017b) but is not otherwise explicitly specified (PUB, personal communication, November 16, 2023).
Types of planned potable reuse approved for use in Singapore
The majority of NEWater is supplied via a separate distribution system to industrial users for non-potable use while a small percentage of NEWater is added to reservoirs to be mixed with raw water. The percentage of NEWater added to the water reservoirs varies and is increased during dry seasons to bolster water security.
Water reuse treatment category/type
Singapore does not assign treated municipal wastewater used for indirect potable water reuse to a category or class of recycled water. The advanced treated water is considered safe to drink.
Additional context and definitions
Singapore has an estimated water demand of 2 million m3/day (PUB, 2023) and has diversified its water sources by adopting a ‘4 National Taps’ strategy which includes imported water, captured stormwater, NEWater and seawater desalination (WHO, 2017a). NEWater and seawater desalination are intended to serve as a ‘drought-proof’ source of water during prolonged periods of low rainfall. The NEWater factories in Singapore have a supply capacity of 760,000 m3/day, almost 40% of Singapore’s water demand (WHO, 2017a) and are a key part of the water supply strategy to preserve the available potable water supplies for human consumption, while ensuring a sustainable supply of recycled water for use by industry. Recycling wastewater multiplies the available water resources in land scarce Singapore. By 2060, the non-domestic sector is projected to increase from the current 55% to 70% of Singapore’s future water demand, and the capacity of advanced treated water will be expanded to meet up to 55% of this future demand (PUB, 2018).
Potable water reuse specifications
Summary of Singapore's Advanced Treated Water Specifications
| Recycled Water Class/Category (Approved Uses) | Source Water Type | Water Quality Parameter | Specificationa | Sampling/Monitoring Requirements (Frequency of monitoring; site/ location of sample; quantification methods)b |
|---|---|---|---|---|
| NEWater – advanced treated water for industrial applications | Treated wastewater | E. coli | Must not be detectable in 100 mL | Not specified |
| Color | <15 True Colour Units | |||
| Turbidity | <5 NTU | |||
| Chlorine | <5 mg/L | |||
| pH value | 6.5-9.5 | |||
| Gross Alpha Activity | <0.5 becquerel/L | |||
| Gross Beta activity | <1 becquerel/L | |||
| Radon 222 concentration | <100 becquerel/L | |||
| Nitrate (as NO3-) | <50 mg/L | |||
| Nitrite (as NO2-) | <3 mg/L | |||
| Barium | <1.3 mg/L | |||
| Boron | <2.4 mg/L | |||
| Lead | <0.01 mg/L | |||
| Fluoride | <0.7 mg/L | |||
| Copper | <2 mg/L | |||
| Manganese | <0.4 mg/L | |||
| multiple | ||||
| Additional chemical parameters | Singapore provides 106 parameter values in “The Schedule” in the 2019 Environmental Public Health Regulations (Water Suitable for Drinking) |
Source = Singapore Statutes Online (2023)
a These values are provided for indirect potable water reuse of NEWater according to Singapore’s Environmental Public Health (Water Suitable for Drinking) regulations. In addition, NEWater also complies with US EPA’s National Primary and Secondary Drinking Water Regulations under the Safe Drinking Water Act and the 2022 WHO Guidelines for Drinking Water Quality (4th Edition, including the 1st and 2nd addenda).
b Information about sampling and monitoring requirements such as frequency, site and quantification methods not specifically listed in the table was not explicitly specified in Singapore’s regulations.
Upcoming regulations
No upcoming reuse regulations related to potable use of treated municipal wastewater were found for Singapore.
References:
Geneva: World Health Organization (WHO). 2017a. Potable reuse: Guidance for producing safe drinking-water.
Geneva: World Health Organization (WHO). 2017b. Potable reuse: Guidance for producing safe drinking-water.
Geneva: WHO. 2022. Guidelines for drinking-water quality: fourth edition incorporating the first and second addenda.
Public Utilities Board (PUB), Singapore’s National Water Agency. 2018. Our Water, Our Future.
PUB, Singapore’s National Water Agency. 2022. NEWater.
PUB, Singapore’s National Water Agency. 2023. Water Conservation.
Singapore Statutes Online. Environmental Public Health (Water Suitable for Drinking) (No. 2) Regulations 2019. Visited on November 20, 2023:
Please contact us at waterreuse@epa.gov if the information on this page needs updating or if this state is updating or planning to update its laws and policies and we have not included that information on the news page.