Updating Manila’s sewerage plan for a changing urban environment
At a glance
We partnered with Maynilad Water Services, Inc. to update the feasibility study for wastewater infrastructure in the City of Manila.
High population density, legacy sewer assets and limited available land create complex requirements for long-term sewerage planning. Using updated operational data, field observations and asset-condition information, we reassessed sewage flows, reviewed network and treatment options, and developed an evidence-based framework to guide future investment decisions.
The study proposes a sewerage system structured into two connected catchments supported by dedicated Water Reclamation Facilities. The proposed configuration is intended to strengthen system reliability and allow phased implementation within a constrained urban environment It provides a practical pathway for expanding sewerage coverage and supporting improved sanitation and environmental outcomes.
The challenge
Manila is among the most densely populated cities in the Philippines. Approximately 1.8 million people live within the city, with an estimated population density of 45,000 per square kilometre.
Parts of Manila’s legacy sewer network date back more than a century, making updated condition assessment, rehabilitation planning and long-term system development increasingly important.
Maynilad is pursuing the long-term expansion of sewerage coverage in the city. As population, asset conditions and operating requirements evolved following the original feasibility study, Maynilad commissioned an update to support future planning and investment decisions to reflect current conditions, projected demand and the realities of a highly urbanised environment.
Our response
We updated the feasibility study with a focus on what is technically workable, operationally sustainable and implementable over time. We reassessed sewage flows using updated population projections and refined the catchment configurations across the city.
Field data informed the assessment. We carried out a six-month water quality sampling programme across 33 locations to understand system conditions and variability. We used the findings to review network capacity and treatment requirements against projected demand.
We also assessed existing assets to understand their condition and potential role within the future system. This enabled us to develop integrated sewerage options that respond to current constraints and future growth. We evaluated different network configurations and treatment approaches, including the initial screening of potential Water Reclamation Facilities sites.
Constructability and operational requirements informed each stage of the assessment. We refined the proposed layouts to account for access constraints, land availability and future maintenance requirements. We also applied an asset-management framework to support risk-based rehabilitation and replacement decisions and help prioritise future investments.
The impact
The study provides a clearer framework for the future operation and development of Manila’s sewerage system.
A key recommendation is the subdivision of the system into northern and southern catchments, each supported by a dedicated Water Reclamation Facility. While the division largely follows the Pasig River, the configuration retains a strategic crossing to maintain connectivity and optimise system performance.
The proposed configuration is expected to distribute treatment capacity across the network, reduce reliance on a single conveyance route and provide greater flexibility as demand and system requirements evolve.
We identified potential Water Reclamation Facility locations through satellite imagery review and structured site screening. The assessment reflects the constraints of a built-up urban environment and supports a phased approach to implementation.
Grounded in current data and aligned with the realities of Manila, the updated feasibility study provides Maynilad with an evidence-based framework to guide future sewerage investments and support its long-term service and environmental commitments.