The Department of Public Works and Highways (DPWH) admitted that outdated and heavily clogged drainage systems in Metro Manila are among the causes of the widespread flooding following days of heavy rainfall due to weather conditions. 

In a televised interview on 23 July, DPWH Secretary Manuel Bonoan said that around 70 percent of drainage systems in Metro Manila are old and heavily silted. 

“Especially the local drainage, about 70 percent are silted, it’s muck that’s inside the drainage,” Bonoan said. He also stressed that flooding cannot be addressed effectively by upgrading pumping stations alone if water cannot reach these stations due to undersized or blocked drains.  

Bonoan noted that the DPWH has adjusted its flood control designs, as the current are based on a 25-year return period and are no longer at par with the increasing intensity and frequency of rainfall. 

“We are now assessing what’s more appropriate either a 50-year or even a 100-year return period. That’s what we are working on.”

As part of the Metro Manila flood control program under the World Bank Assisted Program which started in 2018, the government is also rehabilitating existing pumping stations in order to increase discharge capacity.

The DPWH secretary said 32 pumping stations are being upgraded and are expected to be completed by 2026.

Two new pumping stations are also being constructed in the Tatalon area in Quezon City under the same program. 

To further address risk, floodgates and retarding basins that will redirect excess rain water from the Sierra Madre mountain range toward Laguna Lake are also being developed to avoid immediate flow in Metro Manila. 

DPWH-NCR’s maintenance division chief Josel Bolivar said persistent flooding in certain areas is partly due to the incomplete status of flood control projects. He pointed out that some drainage systems have yet to be fully upgraded, including those in Taft Avenue in Pasay City and Commonwealth Avenue in Quezon City.