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umardi, 60, walked to the backyard of a sewerage plant in community unit (RW) 03 of lower-middle class neighborhood Ma-lakasari in Duren Sawit, East Jakarta, and pointed out four large water inlets in which a series of machines were operating.

 '€œThis is where we clean wastewater from the neighborhood before we dump it in the river behind that wall,'€ Sumardi said pointing to a wall near three orange water tanks.

Sumardi has operated the sewerage machines, which serve 500 houses in the neighborhood since the waste management system was built by the city in 1998.

Malakasari is among neighborhoods that have communal sewerage systems using both aerobic and anaerobic processes in the capital.

As a large metropolis, Jakarta lacks a proper liquid-waste management system. Houses in the city generally only use septic tanks for solid waste and blackwater from toilets, while other wastewater, usually called greywater, is channeled into neighboring drains that feed into rivers.

Data from the city administration shows that service coverage for clean water in Jakarta stands at 60 percent, while wastewater treatment was only 4 percent. Wastewater treatment is key to increasing tap water coverage as it will help increase raw water supply, something for which water operators in Jakarta mostly rely on Jatiluhur Dam in West Java.

In 2013, the Jakarta administration revealed its plan to set up a new wastewater treatment system in the capital. The project, which had been delayed for 15 years, is set to build a total of 15 sewerage zones, is expected to be finished by 2050 and is estimated to cost Rp 70 trillion in investment (US$4.8 million).

Of the 15 zones in the centralized treatment plan, the city has one plant in Setiabudi, South Jakarta. It, however, covers only 2 percent of the city'€™s liquid waste.

Responding to the plan, urban-water spatial planner Prathiwi Widyatmi Putri said that it would be difficult for the city administration to realize the idea as centralized sewerage was costly due to the installation of sewers, including big pipes, in addition to other problems that could occur during the process.

Prathiwi, better known as Ami, explained that sewerage systems heavily relied on sewer installation on the ground, as well as the topography of the area.

Meanwhile, she added in Jakarta, there were already too many underground infrastructure installations, such as telephone and gas systems.

Therefore, Ami suggested the administration install sewerage systems in smaller areas, such as subdistricts or neighborhoods '€” like Malakasari '€” as it would cost less and pose fewer risks to other utility systems.

She emphasized that communal sewerage systems would also reduce the time from water processing to clean water distribution.

At present, Ami said, Jakarta produced more wastewater than the supply of clean tap water, but that with more communal sewerage systems, such as the one in Malakasari, the city could reach a balance between wastewater and clean water, in which treated wastewater could become raw water supply for clean water.

He explained that houses in the community units sent the wastewater to the sewerage machines using a network of pipes.

'€œThe pipes, however, had been clogged several times because of many things, from cutlery to underwear,'€ Sumardi said.

As a sewerage system user, Sumardi said that he had seen many advantages to his work, one of them being that the system makes groundwater in the neighborhood cleaner.(agn)