Skip to content

Asia-Pacific Network for Global Change Research

Asia-Pacific Network for Global Change Research

Read our Science Bulletin

Constructed wetlands as a nature-based solution (NbS) for wastewater treatment: Social acceptability, challenges, opportunities, and policy options for the Philippines

In the Philippines, only 10% of wastewater is treated, and only 5% of the total population is connected to a sewer network. The rest rely on septic tanks and pit latrines and, worst, practice open defecation (Domingo and Manejar, 2021; Philippine Development Plan 2017-2022). Nature-based Solutions (NbS) can address growing water quality and sanitation concerns. Constructed Wetlands (CWs) are an example of an effective NbS for wastewater treatment and water security (UN-Habitat, 2008).

The first CWs treatment facility in the Philippines was built and is being managed by the Bayawan City Local Government Unit (LGU) in Negros Oriental (see Figure 1). Bayawan City is also called the “Agricultural Capital of Negros Oriental.” Bayawan is a component City in the 3rd Congressional District of the Province Negros Oriental. Composed of 28 barangays with a total land area of 69,908 hectares, the city is the largest in the province (Bayawan City Profile, 2022). Rural areas account for 83.1% of the city’s total land area, while urban areas constitute only 2.3% (1,573 hectares) and suburban areas amount to about 10,260 hectares or 14.7% (Bayawan City Profile, 2022). According to the 2020 Philippine Statistics Authority Census, the city’s total population is 122,747.

Figure 1. Philippine map showing the location of Negros Oriental and Bayawan City. Sources: Hue Man, 2023 (left) and Gonzales, 2006 (right)

The major economic activities in the city are farming and fishing. These reflect the key landscape of the city, which is agricultural. The city also has an approximately 15-kilometre coastline, rich in coastal resources. In 1995, an estimated 750 Informal Settler Families (ISF) lived on the coast, which made them highly exposed and vulnerable to disasters. Furthermore, they had no access to safe water supply and sanitation facilities and thus contributed to the pollution of the coastal waters (A. Aguilar, personal communication, August 2022). The City Health Office’s records revealed a significant prevalence of illness and mortality from water-borne infections in these informal settlements (Lipkow and Münch, 2010; A. Aguilar, personal communication, August 2022). To address this, the city government bought a seven-hectare piece of land, now called the GK Fisherman’s Village, as a relocation area for the affected families and installed CWs for domestic wastewater treatment. From May 2005 to August 2006, the City Engineering Office of the Bayawan City LGU worked on the project with technical assistance provided by the German Technical Cooperation or GTZ through its Water and Sanitation Program (Lipkow and Münch, 2010). In September 2006, the CWs system was officially inaugurated. It has been continuously operated and managed by the Bayawan City LGU until now (see Figure 2, photos taken February 2023).

Figure 2. Photos of GK Fisherman’s Village constructed wetlands

The Society for the Conservation of Philippine Wetlands, Inc (SCPW) and researchers from the University of the Philippines Los Baños (UPLB) conducted a case study on the operation of the CWs in Bayawan City as an NbS solution for wastewater treatment in the country, focusing on social acceptability and replicability of the said technology. This study is part of the “Integrated assessment of existing practices and development of pathways for the effective integration of nature-based water treatment in urban areas in Sri Lanka, the Philippines, and Vietnam” project funded by the Asia-Pacific Network for Global Change Research (APN).

Three (3) Focus Group Discussions (FGD) were conducted during field visits on August 16, 2022, and February 9, 2023. The FGDs included 1) block leaders of the GK Fisherman’s Village, 2) Barangay (village) officials and staff in Barangay Maninihon, and 3) Barangay officials and staff in Barangay Villareal, all from the City of Bayawan (see Figure 3).

Figure 3. FGDs on social acceptability for wastewater treatment using constructed wetlands (from left to right: GK Fisherman’s Village Block Leaders, Barangay LGU of Maninihon and Barangay LGU of Villareal in Bayawan City)

Key Informant Interviews (KIIs) were also conducted with selected personnel involved in the operation of the CW. In addition, 270 residents from the GK Fisherman’s Village were also invited to participate in the social acceptability survey. Results showed that 94% of the survey respondents are aware of the CW and its existence in the village. Table 1 summarises the survey results on the social acceptability of the CWs in Bayawan City.

Figure 4. Roundtable discussions during the National Consultation Meeting on NbS for Wastewater Treatment in the Philippines

The study confirmed that CWs are a cost-effective way of treating domestic wastewater to reduce water pollution, which helps improve the community’s health. Key factors affecting social acceptability according to the result of the FGD, the KIIs, and the survey are adequate preparation, participation and involvement of the local community, awareness, trust in the implementers, a feeling of safety, and the perceived impacts and benefits for the community. Moreover, through thematic analysis, it was found that the critical aspects for the sustainability and replicability of the CW in the case of Bayawan City are strong political will, policy and funding support, cooperation of the community (social/public acceptance), the existence of a unit responsible solely for managing the operations and maintenance of the CWs, technical knowledge, and availability of land.

Regarding improvement opportunities for current and future applications, the study suggests that generating more direct benefits, especially provisioning services, which have economic value for the community, is essential to ensure the continued interest and support of local decision-makers and politicians. Currently, the community perceives the CW as beneficial only for its regulatory service, specifically for wastewater treatment.

As part of the APN project, a national consultation meeting on NbS for Wastewater Treatment was organised by the SCPW-UPLB APN Philippine Team. It was a critical step in initiating efforts to document NbS interventions and trigger discussions and actions on their effectiveness and potential for replication in the Philippines. Stakeholder inputs collected during the meeting enabled the development of a framework for NbS replication and identifying necessary policies to support NbS for wastewater treatment. It also increased the awareness, especially among decision-makers, of the potential contribution of NbS to resolving some of the pressing issues and challenges related to water quality in the country.

The meeting was held on October 7, 2022, and included 34 participants from 21 National Government Agencies (NGAs), private institutions, and academic and Civil Society Organizations (CSOs). Ms Amy Lecciones, Executive Director of SCPW, opened the event and explained the event’s objectives to the participants, many of whom are also part of the network of SCPW. The welcome address was followed by three presentations by: (1) Dr Jega V. Jegatheesan, Project Leader of the APN project and Professor from RMIT University Australia, who shared some info about the project; (2) Engineer Antonio S. Aguilar, Jr., Assistant City Engineer of Bayawan City, Negros Oriental, who made a presentation on “Nature-based solution in the Philippines: Bayawan Best Practices”; and  (3) Dr Perlie P. Velasco, from the University of the Philippines Los Baños (UPLB), who presented the draft assessment framework for CWs for domestic wastewater treatment in the country. The presentations were followed by a roundtable discussion facilitated by Dr Ma. Catriona Devanadera (see Figure 4).

The round table discussions focused on the step-by-step process for establishing CWs, challenges and opportunities related to NbS-CW, key factors for replication and up-scaling, policy options and other recommendations for advancing the use of NbS for wastewater treatment in the country. Boxes 1 to 4 show the results of the roundtable discussions during the National Consultation Meeting. The project team is currently working on following up on some of the recommendations. Specifically, it is developing guidelines for establishing, operating, and maintaining CWs based on the example and the lessons learnt from the Bayawan case study. Commitments to further collaboration developed through the workshop are expected to serve as stepping-stones for following up on some of the policy-related recommendations, such as the suggestion for integrating CW in the country’s Nationally Determined Contributions (NDCs) to the Paris Agreement, among others.

Box 1. Challenges to replicating and up-scaling NbS for wastwater treatment in the Philippines
  • Lack of policy, especially on green infrastructure
  • Weak implementation of existing policies
  • Limited political will
  • Limited sustainability and funding support
  • Changes in the Comprehensive Land Use Plan
  • Database management and availability
  • Maintenance for long-term use
  • Availability of space in urban areas
  • Absence of guidelines or frameworks to support implementation
  • Lack of systematic assessment of NbS
  • Compliance with environmental standards
  • Social acceptability
  • Lack of community awareness
Box 2. Opportunities for replicating and up-scaling NbS for wastewater treatment in the Philippines
  • LGUs are potentially critical partners for up-scaling and replication snice the Local Government Code mandates them to ensure basic services and facilities.
  • The Mandanas Law, which directs the full devolution of certain functions of the executive branch to the LGUs, was issued to aid the efficient implementation of the Supreme Court Ruling on the Mandanas-Garcia case and strengthen the autonomy and empowerment of LGUs.
  • Mainstreaming CW is an option, especially in low-density and isolated communities (e.g. small islands).
  • There is also good potential for adopting CWs in rural areas where land is still available.
  • Domestic wastewater treatment through CWs can be included in the services provided at resettlement facilities.
  • Integrating methane capture in Decentralised Wastewater Treatment Systems (DEWATS) would enable access to green financing for scaling.
  • Methane capture and linkage to the Clean Development Mechanism (CDM) as a contribution to the attainment of the Sustainable Development Goals (SDGs).
  • International funding may be available for CWs for climate change adaptation and resilience.
  • Research opportunities for students.
  • Public-private partnerships.
  • NbS can be integrated with ongoing development of the Bill to create the Department of Water Resources and National Wetland Policy.
Box 3. Policy options on how NbS for wastewater treatment can be pursued, replicated, and up-scaled in the Philippines.
  • Exploration of wastewater reuse for agricultural purposes (DA AO 11 series of 2019).
  • Revisit existing laws and policies, including their implementation (e.g. Clean Water Act, Supreme Court Mandamus on Manila Bay) to improve the enabling environment for scaling CWs.
  • The Technical Bulletin for protected areas can recommend the use of CWs when feasible for their management office and visitor facilities.
  • Development of an operation or maintenance protocol on the disposal of organic waste from plants in CWs.
  • Crafting of policies on NbS: Executive Order, Department Administrative Order at the national level, and municipal or city ordinance at the local level.
  • Lobbying LGUs to include CWs as a priority option for treating wastewater in the CLUP and other NGO-mandated reports.
  • Integration in the Climate and Disaster Risk Assessment (CDRA) process for consequent integration in CLUP.
  • In every permit application, the amount of expected wastewater should be considered; relative to this, depending on the expected wastewater amount, NbS can be required.
  • Policy for incentivising NbS as initial buy-in for the LGUs.
Box 4. Other insights and recommendations on how to pursue, replicate, and up-scale NbS for wastewater treatment in the Philippines.
  • Creation of NbS tools and guidelines for government agencies to support implementation.
  • Conduct an integrated assessment of expected impacts before implementing an NbS in a community.
  • Coordination with DENR bureaus for policymaking issues regarding NbS practices.
  • Mapping out wetlands to identify areas that need to be prioritised, how critical the identified areas are, and the feasibility of sustaining them.
  • Collaboration with LGUs, private entities, and other stakeholders.
  • Creation of livelihood opportunities for local communities from NbS.
  • Increase public awareness and participation.
  • Integration of CWs in the national laws relating to sewage treatment (building code, Clean Water Act).
  • Replication and improvement of good practices through innovations in design to enhance flexibility and performance.


Bayawan City Profile. (2022). Bayawan City Official Website. Retrieved August 18, 2022 from

Domingo, S.N. and Manejar, A.J.A. (2021). Review of Urban Wastewater Management  and Clean Water Act. Discussion Paper Series 2021-46. Philippine Institute for Development Studies.

“HueMan1”. (2020). Map of the Philippines showing the location of Negros Oriental [Map]. Wikipedia.

Gonzales, M. (2006). Map of Negros Oriental showing the location of Bayawan [Map]. Wikipedia.

Google Maps. (2023). “Bayawan City, Negros Oriental” [Map].

Lipkow, U. and Münch, E. (2010). Constructed wetland for a peri-urban housing area, Bayawan City, Philippines. Sustainable Sanitation Alliance Project. Retrieved from

National Economic and Development Authority. (2017). Philippine Development Plan 2017–2022.

UN-Habitat. (2008). Constructed Wetlands Manual. UN-Habitat Water for Asian Cities Programme.