Multa Fidrus, Tangerang – Thousands of Tangerang residents living along the Cisadane river are at risk of various illnesses due to the increasing level of pollution in the river, a report says.

Tangerang municipality water company PDAM Tirta Benteng announced Monday that tests of river water had shown alarming levels of contaminant, including manganese, iron, ammonia and sodium.

Company spokesman Indra Wawan Setiawan said the hazardous chemicals could build up as deposits in the human body, causing effects that were likely to become apparent within the next five years. "The effects will range from skin diseases and digestive problems to kidney failure and various kinds of cancer," he said.

He said Tangerang tap water consumers would also be affected, but that people living along the riverbank were at a greater risk as they used water directly from the river for household purposes. He said they were also alarmed by river water seeping into the wells of residents living nearby.

The report was based on recent tests on water samples from the Cisadane River carried out by a joint team of officials from the municipality's environmental agency, health agency and water companies PDAM Tirta Benteng and PDAM Tirta Kerta Raharja.

The tests also found that 11 companies producing a range of products, including ceramics, fibers, chemicals and textiles, had been dumping liquid waste into the river.

PDAM Tirta Benteng president director M. Kodri said the increasing level of pollution had caused water purification costs to increase significantly, and if it persisted, could lead to the disruption of tap water supplies.

"If the problem is not immediately taken care of, the residents will suffer," he said, adding that the dry season had significantly decreased the river's volume.

He said the company's water intake level had decreased from 3 meters to 90 centimeters. If it continues to decrease by 10 centimeter a day, the company will only be able to provide clean water for consumers for the next nine days.

Wild grass has covered the surface of sediment in the river, while algae has blackened the water.

The oxygen level in the water has also dropped below the normal standard, a supporting test from independent laboratory Sucofindo indicates.

"Our pumping engines are currently still working. But the quality of the water is of concern," he said, adding that it would be very difficult to process river water into clean water.