The recent landfill collapse in Rodriguez, Rizal, has renewed scrutiny over waste management practices near the environmentally critical Sierra Madre mountain range — and Senator Risa Hontiveros says the dangers extend far beyond the immediate disaster site.

According to Hontiveros, communities living near landfill facilities may already be facing serious health and environmental threats ranging from contaminated water to disease outbreaks.

“One major concern is water contamination,” she said.

Toxic leachate, a hazardous liquid produced when rainwater filters through garbage, can seep into nearby waterways such as Burgos Creek and flow into the Marikina Watershed, she explained.

“This can potentially affect local deep wells and even Metro Manila’s water supply,” Hontiveros warned.

Residents near landfill sites have also reported worsening air quality, including persistent foul odors and increased pest activity.

“Some residents have already complained of persistent foul odors, along with increased pests such as flies and insects,” she said.

These conditions raise the risk of respiratory illnesses and diseases such as dysentery, salmonella, and E. coli.

Beyond immediate health concerns, Hontiveros pointed to systemic regulatory weaknesses that she believes allow unsafe landfill operations to continue.

“There is a clear gap in oversight of landfill operations,” she said.

The senator cited Department of Environment and Natural Resources (DENR) Administrative Order 2017-15, which she said weakened independent monitoring by removing multi-sector oversight teams.

To address this, she is pushing for the reinstatement of Multi-partite Monitoring Teams and the creation of strict “no-go zones” for waste facilities in protected watershed areas.

Another structural issue, she said, lies in how landfill operations generate revenue for local governments.

“We must also address the structural problem in which local governments rely on landfill tipping fees, which can discourage strict enforcement,” Hontiveros said.

She proposes reforms that would separate local government revenues from waste volume and require real-time digital monitoring of landfill facilities.

The senator warned that landfill operations near the Sierra Madre could have broader environmental consequences.

Known as Luzon’s natural barrier against storms and floods, the Sierra Madre plays a crucial role in protecting downstream communities.

Yet landfill facilities in Rizal Province are operating dangerously close to protected watersheds and conservation zones, Hontiveros said.

She also warned that some operators may be exploiting regulatory loopholes to continue operating in areas the Supreme Court (SC) ruled should be protected under Province of Rizal vs. Executive Secretary, G.R. No. 129546.

“We must immediately audit all landfill permits and environmental compliance in Rizal to ensure no facility is operating beyond safe structural or ecological limits,” she said.

If landfill operations near watershed areas are not strictly monitored, Hontiveros warned that the long-term consequences could be severe.

Toxic leachate could contaminate waterways such as Burgos Creek and the Bosoboso River before eventually reaching critical water sources like Wawa Dam.

“What begins as a local environmental problem could escalate into a serious water security threat for Metro Manila,” she said.

Unchecked landfill expansion could also damage ecosystems in the Upper Marikina River Basin while weakening natural flood-control systems that protect surrounding communities.

Hontiveros said she has already filed a Senate resolution seeking an investigation into the country’s solid waste management system.

“Landfill collapses caused by dangerous ‘no-soil cover’ practices are not just ‘mere accidents,’ but are the result of regulatory negligence,” she said.

She added that the inquiry will examine whether rising garbage fees in Manila are linked to unsafe landfill operations in Rizal.

“Those responsible, both operators and regulators, must be held accountable,” the senator said.