SHANGHAI has launched a series of plans to rework the drainage system to separate wastewater and rainwater.

The repairs or relaying of new pipes will affect 480 residential communities this year.

Officials from the Shanghai Water Authority said that at least in 13,000 places in the city’s 12,000-kilometer pipeline, wastewater gets mixed up with rainwater.

The majority of these places are in suburban areas and workers have to relay the pipes under these buildings. Authorities said more than 60 percent of wastewater is generated by the residential communities.

Wastewater treatment is pivotal as much of the water released by housing complexes and factories have to be treated at sewage treatment plants first before being released back to the environment.

On the other hand, rainwater pipes are connected directly with the water pumping stations, but when wastewater enters the stations through rainwater pipes without being treated, it increases the chances of polluting the rivers and other water sources.

Officials also said because of the thin sewage pipes the communities get flooded during heavy rains.

Wang Jie, from Shanghai Drainage Administration, said wastewater from rain pipes have overwhelmed some of the pumping stations and they had no option but to discharge the untreated water into open areas. A new regulation, that comes into effect from April 15, forbids the stations from discharging water when the weather is dry to avoid large-scale water pollution.

Many residential communities in downtown were built before the 1980s when China started to separate water drainage system. “Some buildings were just too old. They probably didn’t have an idea about such things,” said Wang.

Yi Hua, the manager of Shanghai Yongda Public Facility Construction Group, said the pipes may have rusted and the chances of mix-up was high.

In Maotai Huayuan community in Changning District, property manager Yao Ying said the community had separate pipes for rainwater and wastewater. But wastewater still gets mixed up as residents put washing machines in the balcony.

Similar situations were found in other residential communities nearby.

Business along Shuicheng Road dumped swilling directly into the rain pipes along the street.

“It is critically important to raise people’s awareness on separating wastewater and rainwater,” said Huang Minsheng, an expert on ecology and environmental science from East China Normal University. “Otherwise we are likely to make the same mistakes in the future.”

Rubbish was ledt in agutter in Dujiazhai Community in Changning District from which rain water goes underground.