Adianto P. Simamora, The Jakarta Post
The Bandung Institute of Technology (ITB) has been working on a mobile water treatment system, which can be started up and applied on the spot, in response to the unequal access to potable water in the city.
A single mobile unit has the capacity to treat 400 cubic meters of polluted water a day.
"One unit can serve more than 4,000 people with a production cost of Rp 1,100 per cubic meter," Indratmo Soekarno, the head of the ITB's department of civil engineering, said recently.
He said the treatment units were able to purify dirty water taken from rivers, wells or lakes.
"The quality of the water is of little consequence. One of our mobile units can purify water with a turbidity of 10,000 ppm (parts per million), which cannot be treated by the state-owned water operators," he said.
The dirty water is first oscillated, spiraling heavier particles like sand and sediment away, before being filtered.
Chlorine is then used to destroy disease-causing contaminants.
Indratmo said the technology could also be applied to make seawater potable, with a production cost of Rp 9,000 per cubic meter.
"We are also developing the technology to reduce the production cost still further," he said.
The treatment units were first used in the city during the floods last month, which left millions of people without access to clean water.
The ITB, in cooperation with the Indonesian Medical Association (IDI), deployed two treatment units to Jakarta.
"We set up one unit on Jl. Sultan Agung, East Jakarta, and another in Bekasi, giving free potable water to the flood victims," Hasnah Siregar, the IDI's chief public relations officer, said.
Many of the city's poor have limited or no access to clean water.
A report issued by the United Nations Development Program (UNDP) last year said Jakarta's slum dwellers paid five to 10 times more for water than people living in upscale areas.
The report said almost two in three people lacking access to clean water survive on less than US$2 a day, with one in three living on less than $1 a day.
Half of the some 10 million inhabitants of the city are believed to rely on groundwater.
The administration says groundwater supplies are steadily depleting due to overexploitation coupled with the poor rainwater catchment facilities in the city.
In low-lying North Jakarta, for example, groundwater depletion has caused serious land subsidence, making the area more vulnerable to flooding and allowing water from the Java Sea to seep into the coastal aquifers.
The administration says 80 percent of the groundwater in wells with depths of 10-20 meters is polluted.