Adianto P. Simamora, The Jakarta Post, Jakarta
Amid rising concern over a water crisis in the capital, the city administration has stepped up pressure on industrial sectors to start recycling water.
The Jakarta Mining Agency said the recycled water could be used to meet demands for clean water from companies operating in business districts.
"Recycling water is a must to reduce the excessive exploitation of groundwater," agency head Peni Susanti said Wednesday.
The agency signed an agreement on the management of groundwater with operators of the business areas Mega Kuningan in Central Jakarta, Kelapa Gading in North Jakarta and Mangga Dua in West Jakarta.
The administration, however, did not specify technologies that could be used to recycle water.
"Recycling water has become common practice in several countries to save water," she said.
Recycled water is most commonly used for non-potable purposes, such as agriculture, landscape, public parks and golf course irrigation.
Other applications include cooling water for power plants and oil refineries, industrial process water for facilities such as paper mills and carpet dyers, toilet flushing, dust control, construction activities, concrete mixing and artificial lakes, as stated on the website of the U.S. Environmental Protection Agency.
Although most water recycling projects have been developed to meet non-potable demands, a number of projects use recycled water indirectly for potable purposes.
These projects include recharging groundwater aquifers and augmenting surface water reservoirs with recycled water. In groundwater recharge projects, recycled water can be spread or injected into groundwater aquifers to augment groundwater supplies, and to prevent salt water intrusion in coastal areas.
Peni said the overexploitation of groundwater in Jakarta had accelerated land subsidence, particularly in business districts where many high-rise building have been built.
"In the Mega Kuningan business area, the level of the groundwater is decreasing by five meters per year. The area could collapse unless there is some control of the groundwater use," she said.
According to agency data, 80 percent of the city's land subsidence is caused by building construction, 17 percent by groundwater exploitation and 3 percent by natural causes.
"Therefore, we will invite all managements of the business districts in the capital to sign the agreement," she said.
She said operators of business areas were also required to set up percolation pits to help recharge the groundwater supply.
"They must also dig lakes in their areas to harvest rain in a bid to recharge the groundwater supply," she said.
Businesses, including hotels and hospitals, are the main users of groundwater.
There are currently 3,600 companies in Jakarta that hold permits to take a maximum of 100 cubic meters of groundwater per day.
Since the groundwater reserve has reached critical levels, the administration has stopped issuing new permits for the industrial sector.
Governor-elect Fauzi Bowo, in a speech at a seminar organized by the agency, said he would raise the tariff of groundwater to protect the long-term interests of the city.
The mining agency currently charges companies Rp 4,000 for every cubic meter of groundwater they use. Piped water costs about Rp 12,000 a cubic meter.
Estimates by the Jakarta administration put the city's water needs at around 547.5 million cubic meters per year.
The city's two tap water operators can only meet half of the need as they produce 295 million cubic meters of water per year.