In 2025, Southeast Asia’s (SEA) water and waste sector entered a decisive phase shaped by climate stress, urban growth and tightening environmental regulation. Governments across the region moved beyond policy intent to implementation, focusing on expanding wastewater treatment, strengthening water supply security, reducing plastic leakage and adopting technology-driven solutions.

Although progress differed by country, the year marked a clear move towards stronger, more efficient and environmentally sound water and waste management systems across the region, with increasing use of technology. Southeast Asian Infrastructure takes a look at the water and waste sector roundup for 2025…

Robust wastewater management initiatives

Wastewater management emerged as a key urban infrastructure priority across fast growing SEA economies in 2025, driven by urbanisation and environmental pressures.

In Indonesia, in a major ongoing initiative, Jakarta continued to advance its zone-based sewerage master plan under the Jakarta Sewerage System programme. With centralised wastewater coverage still below 2 per cent, the initiative represents a structural shift in the city’s sanitation strategy. By dividing Jakarta into 15 sewerage zones, the programme aims to expand coverage, reduce surface water pollution and curb groundwater contamination from uncontrolled on-site systems. In September 2025, Indonesia also introduced a new nationwide domestic wastewater regulation in a move to boost water quality and sanitation.

The Philippines recorded steady gains through multilateral development bank-backed programmes that explicitly link wastewater management with coastal and marine protection objectives. New investments in 2025 focused on Metro Manila, Cebu and Davao, prioritising sewerage network expansion, septage treatment capacity and tighter control of wastewater outfalls. As of June 2025, Manila Water was providing sewerage services to 311,663 connections. Coverage remained dominated by combined sewer systems, accounting for 247,756 connections, while separate systems, hybrid systems and private sewage treatment plants represented smaller but gradually expanding segments. The year-on-year increase of 4.67 per cent in the provision of household connections, equivalent to 13,895 additional connections compared to the same period last year, indicates steady progress in dense urban areas.

Vietnam continued to expand urban wastewater treatment capacity in major metropolitan centres such as Hanoi and Ho Chi Minh City, as well as in key provincial cities. In August 2025, the Yen Xa Wastewater Treatment Plant was inaugurated. The facility has a capacity of 270,000 cubic metres per day and deploys conventional activated sludge process.

Thailand and Malaysia adopted a more consolidated and focused approach. Thailand concentrated on upgrading and optimising existing municipal wastewater treatment plants, with particular attention to operatio­nal performance in tourism-intensive coas­tal cities where effluent quality directly affects local economies. Malaysia prioritised regulatory compliance upgrades and the use of public-private partnership (PPP) models to ­stre­ngthen municipal wastewater systems, espe­cially in rapidly urbanising development corridors. Singapore remained at the technological frontier, with continued investment in adva­n­ced wastewater treatment and industrial water reuse, exemplified by new industry-linked facilities such as the advanced treat­­ment plant being developed on Jurong Island.

Ramping up water supply infrastructure

In 2025, growing climate challenges have spurred SEA governments to strengthen and diversify water supply infrastructure, enhancing regional resilience. In line with this, innovative methods to enhance water security are being explored across the region. For instance, as of December 2025, Singapore’s Public Utilities Board is conducting feasibility studies for a potential sixth desalination plant, demonstrating continued investment in expanding water infrastructure to safeguard supply and security. These efforts complement the ongoing expansion of water reuse under the NEWater programme, reinforcing Singapore’s long-term strategy to reduce dependence on freshwater resources.

Advancing circular economy initiatives

Across SEA, circular water economy app­roaches gained traction in 2025, with governments, development partners and industry exploring systems that recover and reuse water, reduce discharge and close resource loops. A notable example is the pilot project on industrial wastewater reuse laun­ched at the Deep C Industrial Zones in Vietnam in November 2025 under the United Nations Development Programme-led Accele­rate Circular Economy Business Programme. This initiative combines nanofiltration and reverse osmosis technologies to treat industrial effluent to reuse standards, enabling its use for cooling and other processes within the industrial park and laying the groundwork for larger-scale reuse across other zones.

Complementing this, various initiatives were undertaken across the waste sector in SEA countries. In Thailand, policy momentum was driven by decisive regulatory intervention. The country implemented a complete ban on plastic waste imports in January 2025, fundamentally altering regional waste trade patterns. The ban forced a rapid recalibration of domestic waste management systems, accelerating investment in recycling infrastructure, sorting facilities and downstream processing capacity.

Technology-driven transformations

In 2025, the SEA region saw a surge in water-related technology deployments as utilities sought innovative solutions to improve operational efficiency and enhance climate resilience amid growing environmental challenges. Digital solutions gained traction, including smart metering, leak detection and remote monitoring for both water and wastewater utilities. AI-enabled routing and data analytics are being increasingly deployed for municipal waste collection, improving efficiency and reducing costs. Waste-to-energy and landfill gas recovery projects have ex­pan­ded, supporting emissions reduction goals.

in December 2025, Malaysia reached a significant milestone with the completion of its first water treatment plant (WTP) to deploy an asset digital twin, at the Semenyih 2 WTP. Now fully operational, the facility integrates digital twin technology across its systems, representing one of the most advanced applications of smart water technologies in the region. The Semenyih 2 plant treats around 100 million litres per day and features a digital twin platform, enabling real-time monito­ring, operational optimisation and predictive analytics for enhanced asset management.

Navigating forward

Looking ahead, utilities are shifting from incremental capacity additions to system level transformation, backed by stronger governance, targeted investment and technology adoption. By end 2025, progress was marked by structured, finance-backed programmes, though unevenly. The next phase will test delivery on performance, financial viability and environmental gains. Priorities include scaling digital, data-driven operations to cut losses, optimise energy use and improve reliability, alongside decentralised modular systems for rapid rural and urban expansion. Reflecting this, in August 2025, Hydroflux Engineering Private Limited deployed two 20,000 litres per day RapidSmart membrane bioreactor units on Batam Island, Indonesia.

Across both the water and waste sector, stronger institutions, better project preparation and innovative financing will be critical. Blended finance, PPPs, and performance-linked contracts can crowd in private capital, while regional knowledge sharing and clear pilot-to-scale pathways will accelerate replication of successful, sustainable models.