The National Disaster Coordinating Council said Tuesday the homes of nearly 1.9 million people in the capital and surrounding areas were inundated, with nearly 380,000 people brought to schools, churches and other evacuation centers.
Overwhelmed officials have called for international help, warning they may not have sufficient resources to withstand another storm that forecasters say is brewing east of the island nation and could hit as early as Friday.
Tropical Storm Ketsana, which scythed across the northern Philippines on Saturday, dumped more than a month's worth of rain in just 12 hours, fueling the worst flooding to hit the country in more than 40 years.
Troops, police and volunteers have already rescued more than 12,359 people, but unconfirmed reports of more deaths abound, Defense Secretary Gilbert Teodoro said.
He told a news conference that help from foreign governments will ensure that the Philippine government can continue its relief work.
"We are trying our level best to provide basic necessities, but the potential for a more serious situation is there," Teodoro told a news conference. "We cannot wait for that to happen."
The extent of devastation became clearer Monday as TV networks broadcast images of mud-covered communities, cars upended on city streets and reported huge numbers of villagers without drinking water, food and power.
In Manila's suburban Marikina city, a sofa hung from electric wires.
Since the storm struck, the government has declared a "state of calamity" in metropolitan Manila and 25 storm-hit provinces, allowing officials to use emergency funds for relief and rescue.
Resident Jeff Aquino said floodwaters rose to his home's third floor at the height of the storm.
Aquino, his wife, three young children and two nephews spent that night on their roof without food and water, mixing infant formula for his 2-year-old twins with the falling rain.
Among those stranded by the floodwaters was young actress Christine Reyes, who was rescued by movie and TV heartthrob Richard Gutierrez from the rooftop of her home near Manila after she made a frantic call for help to a local TV network with her mobile phone.
Gutierrez, a close friend and Reyes' co-star in an upcoming movie, heard of her plight, borrowed an army speedboat and ferried Reyes, her mother and two young children to safety.
Rescuers pulled a mud-splattered body of a woman from the swollen Marikina river Monday. About eight hours later, police found three more bodies from the brownish waters.
The United States has donated $100,000 and deployed a military helicopter and five rubber boats manned by about 20 American soldiers from the country's south, where they have been providing counterterrorism training. The United Nations Children's Fund and the World Food Program have also provided food and other aid.