Adianto P. Simamora, The Jakarta Post, Jakarta
Extensive groundwater contamination has left the city administration with no other choice but to instruct each household to install an onsite wastewater treatment system.
The measure was stipulated in a 2005 gubernatorial decree on wastewater management, but has yet to be enforced.
"Gray water, which has been polluted with synthetic detergents, is routinely poured down the drain. This comprises 80 percent of groundwater pollution," Dulles Manurung, the head of the licensing division of the Jakarta Environmental Management Agency (BPLHD), told The Jakarta Post on Tuesday.
The agency will initially target upscale residential areas, such as Pondok Indah in South Jakarta.
"Homeowners must replace traditional septic tanks with onsite wastewater disposal systems," Dulles added.
The 2005 decree requires all homeowners to treat gray and black (flushed) water before disposing of it.
Gray water includes wastewater from bathtubs, showers, washbasins, washing machines and kitchens, whereas black water is from toilets.
It says gray water should be left to stand before being channeled into the treatment facility.
The decree will affect both new and old houses across the city.
Dulles estimated there were septic tanks in more than four million homes across the city.
"It is difficult for us to change people's habits because septic tanks have been used for over 400 years now, but we have to do it to save the environment."
He said installing a wastewater treatment facility would cost Rp 2.9 million per unit, lower than the price of a septic tank at Rp 3.2 million.
The National Development Planning Board (Bappenas) earlier said the more than 10 million people living in Jakarta each produced between 875 grams and 1.75 kilograms of feces every week.
However, there are only about 220,000 buildings, mainly in Central Jakarta, which use the piped wastewater facilities established by city sewerage company PD PAL.
The figure is far below that of other Asian capital cities. All of Seoul's 9.7 million residents uses piped sewerage, 35 percent of Bangkok's population does and in Manila, 16 percent of the population use official means of treating waste.
The mandatory use of wastewater treatment facilities also applies to the operators of hotels, apartments, private and state offices as well as shopping malls.
"We will also check the buildings and withdraw the business permits of operators who have failed to build wastewater treatment facilities on their premises," Dulles said.
He added that developers who wanted to build housing complexes were required to establish communal sanitation systems.
"We are in the process of certifying 13 companies to produce the wastewater treatment facilities. It will then be up to the building operators or homeowners to make their selections," he said.
More than half of the city's inhabitants rely on groundwater for their daily water needs.
The administration has said groundwater collected from a depth of less than 40 meters is no longer safe to drink.
Health Ministry data shows that of every 1,000 babies born in the city, 50 die of diarrheal diseases, often caused by drinking water polluted with fecal matter.
Aside from the poor quality, the supply of groundwater to Jakarta has posed a serious problem to the city. Water shortages have come to be an inevitable part of the dry season, while flooding affects large areas of the city in the rainy season.
Last week, the administration launched a campaign to promote the use of percolation pits to harvest rainwater and replenish groundwater reserves.
The owners of buildings with a roof area exceeding 50 square meters are required to build a pit that can hold 2,000 liters of water.