MANILA: Metro Manila’s water supply could come under increasing pressure as a strong El Nino brings prolonged dry conditions and reduces water inflows into reservoirs serving the capital region.
The Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) describes El Nino as a climate phenomenon characterised by unusually warm sea surface temperatures in the central and eastern tropical Pacific Ocean.
In the Philippines, it is commonly associated with below-normal rainfall, prolonged dry spells and increased temperatures.
Pagasa has warned that a strong to very strong El Nino could persist through the first quarter of 2027, with its effects potentially extending into the first half of the year.
This could affect water availability for households, agriculture and other sectors that depend on rivers and reservoirs.
Metro Manila’s water supply comes primarily from the Umiray-Angat-Ipo River System, which accounts for approximately 91% of the combined water requirements of the East and West Concession Areas.
At the centre of this system is Angat Dam in Bulacan, a major source of raw water for household consumption. It also supplies water for irrigation and supports power generation.
Water from Angat passes through Ipo Dam before reaching the Novaliches Portal, where it is divided between Manila Water and Maynilad. The two concessionaires treat the raw water at their respective facilities before distributing it to consumers.
Metro Manila also gets part of its water supply from Laguna Lake, which serves as another raw water source for the two concessionaires.
Reservoir levels help authorities assess available water reserves and determine whether adjustments to water releases and allocations are necessary.
The National Water Resources Board (NWRB) reduced Metro Manila’s raw water allocation from Angat Dam to 44 cubic meters per second (CMS) in October, down from the usual 50 to 53 CMS, as authorities manage available water resources.
Although water supply remained sufficient when the adjustment was implemented, the reduction underscores the need to manage available reserves amid the possibility of a prolonged dry season.
As of 8am on Nov 3, Angat Dam’s water level stood at 208.70m, 1.30m below its normal high water level of 210m, according to Pagasa.
The reading was slightly higher than the 208.64m recorded the previous day. However, the slight increase does not necessarily mean that water reserves are recovering sufficiently to meet future demand.
Authorities also consider rainfall, water inflows, releases and changes in reservoir levels over time when assessing available supply.
The United Nations Philippines warned that El Nino could increase heat stress, malnutrition and climate-sensitive diseases, lead to water scarcity, and place additional pressure on health systems and essential services.
In a statement on Oct 22, the UN said limited water availability could affect hygiene practices, healthcare delivery, maternal health services and nutrition outcomes, particularly among vulnerable populations.
The UN also warned that climate shocks could threaten crops, livestock and fisheries, potentially reducing agricultural output, driving up food prices and lowering household incomes.
Meanwhile, environmental group EcoWaste Coalition stressed the need to prioritize communities with limited access to reliable water systems, particularly those whose residents still travel long distances to fetch water.
EcoWaste Coalition program manager and environmentalist Jove Benosa said authorities should identify existing water sources, estimate available supply and match it with the demand of households, industries and the agricultural sector.
He also urged local governments to establish water-rationing protocols before shortages become critical, including clear guidelines on delivery schedules and the volume of water to be distributed.
“This should especially take into account the demand from sectors that primarily need water, such as ordinary households, industries and agriculture, because these are the sectors that will surely be affected,” Benosa said.
For Metro Manila, however, a reduction in raw water availability does not automatically mean households will experience interruptions in their water service.
Maynilad explained that the effects of El Nino on water services depend on several factors, including raw water availability and quality, treatment capacity, and distribution conditions.
Water must still undergo treatment and pass through distribution networks before reaching consumers, making dam levels only one part of the overall water supply system.
Alongside adjustments in water allocations and the identification of alternative sources, water authorities and concessionaires have urged consumers to use water responsibly as the dry months approach.
Maynilad advised its customers to adopt simple conservation practices, including properly turning off faucets when not in use, reusing water for non-potable activities such as cleaning and toilet flushing, and immediately repairing leaking indoor pipes.
Consumers were also encouraged to report visible leaks along streets to their water concessionaire for prompt repairs.
Maynilad said it continues to coordinate with the Metropolitan Waterworks and Sewerage System (MWSS), NWRB and PAGASA to monitor raw water conditions and prepare for the possible effects of prolonged dry weather.
The concessionaire also said it would issue separate advisories through its official channels if changes to water services become necessary because of dam conditions. - Philippine Daily Inquirer/ANN
