As the climate crisis hits, here’s how Singapore’s national water agency is pivoting

Oleh Si Ying ThianYogesh Hirdaramani

Continual investments in technology and research, innovative infrastructure design and circular economy principles can help Singapore build a resilient and sustainable water future, says Ridzuan Ismail with Singapore’s national water agency, PUB.

Ridzuan Ismail at a global smart water event in Washington DC, USA, in 2022. Image: Ridzuan Ismail's LinkedIn.

In 1963, a prolonged dry spell in Singapore meant that the country’s then newly formed water agency, PUB, had to impose water rationing for almost nine months.


Even before today’s heightened awareness of the climate crisis, the country has been considered one of the most water-stressed areas in the world, with limited natural water resources and space to store water.


Today, the PUB’s strategy relies on “four national taps” to maintain a sustainable water supply: imported water, catchment water, recycled wastewater known as NEWater, and desalinated water.


But as the climate crisis ushers in some of the hottest months on record in Singapore, and climate scientists project more dry spells and unpredictable weather, these sources of water are increasingly under threat.


GovInsider speaks to PUB’s Chief Sustainability Officer, Ridzuan Ismail, to learn what measures the agency is deploying to tackle this problem.

A double whammy: Water-resilient sources are more energy-intensive


Singapore’s Third National Climate Change Study, which details climate change projections up to 2100, found that dry spells could be more frequent and last longer, Channel NewsAsia reported.


"This will put greater stress on conventional water sources, such as local catchment water and the water we import from Malaysia,” says Ismail. Such dry spells could mean that reservoirs trap less water, while water imports from Malaysia may slow down.

While NEWater and desalinated water have higher water-resilience, they are relatively more energy-intensive. Image: PUB.

In the past, Singapore has dealt with these challenges by expanding Singapore’s catchment area to harvest rainwater on a large scale – thanks to an 8,000 km long network of rivers, canals, and drains that weave their way across the island, two-thirds of the country is utilised as water catchment.


But the need to climate-proof the country’s water supply means “a growing reliance on NEWater and desalinated water,” says Ismail.


However, he also points out the energy intensity of producing water-resilient sources will increase PUB’s energy usage and carbon footprint in the long-run.


A holistic approach to water management – closing both water and carbon loops – is needed to bolster Singapore’s resilience and sustainability amid climate change, says Ismail.

Recycling water endlessly, closing water and energy loops


Continual investment in research and technology and circular economy principles are needed to close both water and energy loops.


For example, innovating processes of water reclamation, used water treatment and NEWater production has enabled PUB to “reuse water endlessly,” quoting Ismail.


However, these processes tend to be more energy-intensive, so measures are taken to reduce their energy impact.


“An emerging challenge for PUB is to address the imperative to close the carbon loop. We are looking for novel ways to reduce our carbon emissions to ensure PUB can continue deliver on its mission in an environmentally sustainable manner,” he says.


Through innovative infrastructure design, such as the country’s 206 kilometres-long Deep Tunnel Sewerage System, PUB uses gravity, rather than energy-intensive pumping systems to convey water. The system essentially conveys used water to three centralised water reclamation plants across the island.


“The conveyance of used water via gravity instead of energy-intensive pumping stations enhances the robustness and reliability of the used water collection system,” Ismail explains.


Conceived in the 1990s, the infrastructure is designed to meet Singapore’s long-term needs for 100 years after completion, he adds.

The Marina East Desalination Plant achieves multiple land use by situating treatment facilities underground while integrating a green roof with a public open space. Image: Keppel.

According to a Straits Times article, the tunnels are expected to be operational by 2026, a year later than previously announced due to construction delays from COVID-19.


Similarly, the Marina East Desalination Plant, which treats freshwater from Marina Reservoir and desalinates seawater, achieves multiple land use by situating treatment facilities underground while integrating a green roof with a public open space for leisure use.


PUB is currently partnering with the National Environment Agency on Singapore’s first integrated water and waste treatment facility, known as the Tuas Nexus. The facility will be energy self-sufficient, as the agencies aim to repurpose waste products to produce biogas that can sustain the facility.


In 2024, PUB also introduced mandatory water recycling requirements for new projects in water-intensive industries, such as wafer fabrication, electronics, and biomedical industries.

PUB’s net-zero goals


PUB has set a target to achieve net-zero emissions by 2045, part of the Singapore government’s broader objective, by adopting a three-pronged approach known as 3Rs.


First, PUB aims to reduce energy required for water treatment processes, such as desalination, which requires several times more energy to treat than catchment water.

Sembcorp Tengeh Floating Solar Farm is one of the world's largest inland floating solar farms. Image: Sembcorp.

Second, PUB to replace electricity needs with renewable energy sources. For example, in 2021, PUB launched a 60 megawatt-peak floating solar farm at the Tengeh reservoir, one of the world’s largest inland floating solar photovoltaic systems.


“The electricity generated from the solar farm will be sufficient to power Singapore's five local water treatment plants, offsetting about 7% of PUB's annual energy needs and reducing PUB's carbon footprint,” stated PUB’s 2021 press release.


Ismail adds that PUB will be launching an upcoming floating solar farm at the Pandan area in Singapore.


Third, PUB aims to remove emissions through carbon removal technologies. PUB is currently partnering to build the world’s largest facility for ocean-based carbon dioxide removal, at PUB’s research and development facility in Tuas, located in Western Singapore.


According to its press release, the US$20 million facility capable of 3,650 metric tons of carbon dioxide removal per year while producing 105 metric tons of carbon-negative hydrogen.