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Editor's Notes

1. To provide a better understanding for the audience on the background of Singapore; Singapore is located off the southern-most tip of the Peninsula Malaysia, and has a total land area of 697 km2, with a local population of 4.5million. We are very fortunate to receive a high rainfall of 2.4m annually. As the island is highly populated and developed, most of these rain would either runoff, or could not be stored due to lack of storage space. Further to that, the high evaporation rate also resulted in tremendous lost of these water. With an average daily demand of 1.3mil m3 or about 300 million gallons, this make Singapore being listed as one of the water scarce country in the world
2. The Ministry of Environment and Water Resources (MEWR) focuses on management of water, land, air and public health. The operational undertakings in these areas are carried out by our two statutory boards, the National Environment Agency (for Clean Land, Clean Air, and Public Health) and the PUB (for Clean Water) Touching very briefly on the four main areas of the Ministry’s work:- Clean Land: is about managing waste solid waste, its collection and disposal, as well as controlling land-based pollution Clean Air: is about ensuring that air quality in Singapore is good and remains within international standards Public Health: our efforts are focused on maintaining a high standard of public cleanliness and hygiene, ensuring the living environment is disease-free, and that Singaporeans can enjoy clean, wholesome cooked food. Clean Water: the efforts centre on providing a clean and adequate supply of water for Singapore. Formed in 1963 to be the authority in charge of potable water, electricity and gas Corporatised electricity & gas entities in 1995 . Water functions remained with PUB together with regulatory functions of the electricity & gas industries Reconstituted with effect from 1 April 2001 Took over sewerage and drainage functions Now is national water agency responsible for the integrated management of Singapore’s water supply, water catchment and sewerage
3. B efore the mid-1970s, Singapore’s local water supply was obtained from the protected forested catchments in the central part of the island. With rapid population and economic growth, water demand increased and additional sources beyond these protected catchments had to be developed in the 1970s and early 1980s to meet the rising demand. These additional sources untapped semi-rural catchments where some degree of urbanisation already existed. Suitable large catchments were identified and existing incompatible activities such as pig farming and pollutive industries were relocated to non-water catchments. Squatters were resettled and backyard industries relocated. All premises in the catchments were completely sewered. Strict anti-pollution measures were introduced and legislation was enacted to protect the water source. Through judicious landuse planning and control, incompatible landuses such as pollutive industries were planned outside the water catchments. With the catchments cleaned up; a system of pollution control measures and enforcement in place, runoff from unprotected catchments was also tapped to supplement Singapore’s water supply. Runoff from the unprotected catchments is largely stored in reservoirs which were formed either by constructing dams across river estuaries or dykes along the coast. The quality of the raw water from these unprotected catchments is satisfactory and suitable for potable water use after conventional treatment with ozonation.
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5. As water from less pristine catchments such as those from urbanized catchments is tapped for water supply, there is a constant need to review the treatment technologies employed to ensure that the treated water quality continues to meet internationally accepted water standards. Apart from source control to ensure that the raw water quality is not polluted beyond economical treatment, the water treatment process employed is largely conventional and widely used with provisions for advanced processes to treat emerging contaminants should the need arise. The processes consist of: Pre-chlorination; Chemical coagulation and flocculation using aluminium sulphate as the primary coagulant, hydrated lime for pH correction and polyelectrolyte to enhance the quality of the flocs; Clarification using pulsator-clarifiers; Filtration using rapid sand filters; Primary disinfection using ozone or chlorine; and Post treatment using hydrated lime for pH adjustment to prevent corrosion in the distribution system and chloramination for residual disinfection. The treated water is fluoridated to prevent dental caries. With membrane filtration (microfiltration and ultrafiltration) becoming more affordable in terms of capital and operating costs, waterworks which are undergoing the upgrading have been retrofitted with membrane filters to replace the rapid sand filters. As catchments with increasing intensities of urbanization will be tapped for potable water supply, provisions are also made in waterworks for membranes processes, such as nanofiltration or reverse osmosis, to be installed to provide more robust treatment for emerging contaminants.
6. Potable water treated from waterworks is being pumped to service reservoirs for storage before distribution. The service reservoirs serve to regulate the daily demand fluctuations. From the 14 service reservoirs around the island, the water is sent via gravity into transmission mains and subsequently into distribution mains to the customers. Although bulk of the water is supplied to customers via gravity flow from service reservoirs located on high grounds, there are some other areas where water is supplied via localised boosting system or high level tanks, to serve customers in landed premises at ground level higher than 37 m above mean sea level.
7. The management of water quality encompassed 5 key trusts; Ensuring and maintaining a good water quality leaving the waterworks, with regular water quality monitoring maintained, both online and grab samples, with focus on surrogate parameters such as pH, conductivity, residual chlorine and turbidity. The whole supply chain from the source to the customer meter position, is managed in an integrated manner in line with the Hazard Analysis and Critical Control Points (HACCP) as spelt out by the WHO Guidelines for Drinking Water At the customer premise, enforcement and code of practice are used to regulate and ensure the quality of water PUB also engages an independent international External Audit Panel, comprises of renowned professors led by Prof Joan Rose, to scrutinize water quality data and process control, including the water supply network. Overriding all, PUB focus on R&D efforts, so as to maintain constant improvement in work flow, in particular, to ensure that the quality of water supplied to the customers are wholesome.
8. Load despatch from waterworks is managed 24/7 centrally by the Woodleigh System Control Centre (WSCC) to the 14 service reservoirs and distribution zones.
9. Besides monitoring water quality at the source and the waterworks, the quality of water is monitored online throughout the water supply network from the moment water leaves the waterworks and at critical control points on the trunk mains, inlet and outlet of the service reservoirs. PUB also monitors the toxicity in treated water using fish at these locations. Surrogate parameters are measured using onsite sensors and analysers located at the various strategic and critical control points. These are monitored online at the WSCC. PUB is currently looking into development of mobile online water quality monitoring system to allow for strategic monitoring throughout the distribution network. Routine sampling is also performed daily at all waterworks, service reservoirs and distribution network. Over 1 70 (service reservoirs included) samples are collected weekly at different locations, including both supply directly from the PUB mains or customers’ premises. Over and above this, PUB carries out specific sampling programmes for more sensitive locations such as schools and hospitals. The parameters monitored include physical, chemical and biological. Surrogate parameters are selected for monitoring to provide indicative representation of the water quality. Surrogate parameters such as turbidity, pH, conductivity and total residual chlorine are monitored online. On top of the above surrogate parameters, free chlorine, and bacteriological parameters such as total coliforms and E-coli are also monitored through routine daily sampling. Over and above, the operation team also carries out investigative sampling whenever there’s any feedback and complaints pertaining to water quality. Special monitoring is also practiced when important events are happening in town.
10. More sophisticated (and pricey) Fish Biosensors are also deployed at some critical locations. They are capable of monitoring the fish breathing through electrical signals. These Fish Biosensors are very sensitive and serve as an early warning system. Operators at WSCC can be alerted automatically whenever the fish is agitated by any toxicity present in the water. The Fish Biosensor setup is also capable of performing auto-sampling when water quality is in question.
11. Throughout the years, PUB has been using fish (mainly tiger barbs) in conventional fish tanks to monitor the toxicity of the water, including treated water in the supply network. The treated water is de-chlorinated before passing through the fish tanks. These fish monitoring systems are deployed at key locations such as critical points along trunk mains and service reservoirs. CCTV with telemetry link to WSCC is used to monitor the well-being of fishes in the tanks.
12. PUB had also worked with our local research agency, A*Star, to use imaging system to monitor the activity of the fish in conventional fish tanks. The system developed is known as the “Fish Activity Monitoring System (FAMS)” which detects the movement of fishes by counting the silhouette of fishes. The current capability of the FAMS is limited to indicating whether the fish is dead or alive. Further enhancement is being made to extend its capabilities to monitor the activity of fishes, to be more comparable to the capabilities of the Fish Biosensor.
13. Although PUB’s legal boundary on water supply is up to the customers’ meter position, as the national water agency in Singapore, PUB’s moral obligation is to investigate all water quality reports up to the customers’ taps and to ensure customers take all necessary corrective action. In order to maintain the water quality in customers supply system, PUB stipulates that all plumbing works for potable water shall be carried out only by PUB licensed water service plumbers. This ensures that the safety aspects of drinking water supply are not compromised. In addition, Professional Engineer (PE) and Licensed Plumber (LP) employed for any water service work are to ensure and certify that all plumbing works and water fittings comply with PUB’s stipulated standards and requirements.. PUB also maintains and updates the Public Utilities Act and the Public Utilities (Water Supply) Regulations, in order to manage any enforcement actions required to maintain the standards.
14. PUB adopts a holistic approach to Integrated Water Resources Management (IWRM). PUB has a comprehensive programme to monitor water quality for the entire supply chain from source to tap. Throughout the water cycle, PUB maintains numerous sampling locations, and at critical areas, online water quality monitoring facilities are incorporated to provide real-time information for operation needs. To better integrate the water quality data, which are essentially managed by different functional groups down the operation line, PUB developed the “Water Quality Data Management System” to aggregate the sampling data. These provide a central platform for all the water quality to be stored and managed systematically. To further integrate these sampling data with online water quality data, the “Integrated Water Management system (IWMS)” is also developed. IWMS integrates PUB’s operations with water quality data and it encompasses a central archive of all quality data for raw water, drinking water and NEWater. Through data mining and business intelligence tools, IWMS enables real-time analysis and trending of water quality. IWMS was set up as an integrated operation system to better manage and utilise data in water operations for analysis and decision making. IWMS aims to drive performance across the enterprise by integrating PUB’s operations with a business intelligence system. There is a need for an integrated operation system to: Ensure all treated water comply with internationally accepted water standards; Enhance integrated water quality management from source to tap – a key component of PUB’s Integrated Water Resources Management; Provide a central platform for real-time access to water quality analysis and trending; Ensure tighter control of water quality from source to tap; and Provide opportunity for water quality data to be tapped for R&D
15. PUB has in place a comprehensive and integrated water quality management system to ensure safety of water from source to tap. Through vigilance, agile response to customers’ reports and an efficient management of the water quality system, PUB is constantly on its toes to meet the challenges in ensuring water supplied to customers is safe, wholesome and of the highest quality. This also mean constantly scanning the horizon for means and methods to further enhance the water quality management system and PUB’s service to customers.
16. PUB has in place a comprehensive and integrated water quality management system to ensure safety of water from source to tap. Through vigilance, agile response to customers’ reports and an efficient management of the water quality system, PUB is constantly on its toes to meet the challenges in ensuring water supplied to customers is safe, wholesome and of the highest quality. This also mean constantly scanning the horizon for means and methods to further enhance the water quality management system and PUB’s service to customers.