To overcome water shortage caused by a growing population and limited resources close by, water needed to be drawn from Laguna Lake, one of the largest inland water bodies in Asia. Yet, Laguna Lake’s waters are among the world’s most challenging to treat due to a high concentration of algae and suspended solids.

Acting as the project manager on the client’s side, Arup has undertaken a feasibility study, developed the project specifications, and managed the procurement process and contract administration.

Putatan Water Treatment Plant 2’s state-of-the-art membrane technology enabled Manila to make use of water resource in Lake Putatan, which was previously untappable, with complete ease. With 150 million litres of water delivered per day, water security for Metro Manila has been strengthened.

Planning for complex water stresses

Arup was appointed by Maynilad to lead the feasibility work and manage project implementation. Our feasibility study utilised data from the nearby Putatan Water Treatment Plant 1 to more deeply understand the trends of lake water quality.

Understanding the complex issues surrounding water quality in Laguna Lake was critical to the project’s success. In particular, the study highlighted the importance of designing for rapid and potential worsening of water quality to ensure a reliable water service. These insights enabled us to select, identify and specify a process which could provide robust treatment across a range of different conditions. We were then able to specify a number of advanced technical pre-treatment processes, including dissolved air floatation (DAF), biological aerated filtration (BAF), ultrafiltration (UF), followed by reverse osmosis (RO) before a final chlorination step.

The Putatan WTP2 is now the most advanced water treatment plant in the Philippines, delivering 150ML of water per day.

Aerial view of Putatan Water Treatment Plant 2. Credit: Photosynthesis Inc.
The new plant can handle the highly variable quality of raw water coming from Laguna Lake, thus helping to sustain reliable water services.

An innovative design on a small footprint

Apart from the complexities of the water treatment process, Arup was tasked to design the plant on an extremely small footprint. Such limitations are common with water and wastewater projects in Metro Manila, due to the huge pressures on developable space.

Arup was responsible for developing solutions to accommodate a tight site of less than 100m wide and 300m long. This posed substantial challenges for the team, as a typical water treatment plant would usually be designed across a much larger land area. We also had to consider constraints such as site flooding in the high seismic region and existing drainage paths. To counter these constraints, we successfully planned a three-storey treatment plant which allowed the plant’s facilities to be “stacked” across different levels.

This award-winning project is helping Metro Manila relieve major water shortages and safeguard the city’s future water supplies. The success of Putatan WTP2 offers potential for the implementation of such advanced water treatment facilities in similar scenarios in other parts of the world.

Three-storey “stacked” treatment facility
The three-storey “stacked” treatment facilit

The addition of Putatan Water Treatment Plant 2 increases our ability to meet the needs of our customers and provides enhanced water security. The new plant can handle the highly variable quality of raw water coming from Laguna Lake, thus helping to sustain reliable water services.

Ramoncito Fernandez

President and CEO, Maynilad Water Services, Inc