The city of Beijing has floated a plan for a 230 kilometer network of waterways that improves the urban ecosystem and helps quench the thirst of the capital’s 20 million people.

The city government introduced the plan in April, saying six to eight years would be needed to build the proposed “ring roads of water.” Officials did not say when work might begin.

Supporters of the plan include Jia Shaofeng, a researcher at the Institute of Geographic Sciences and Natural Resources Research at the Chinese Academy of Sciences (CAS). If planned properly, he said, the network would “benefit the city by reducing water pollution, cleaning waterways, and enhancing the (public water) system’s flood control capacity and ecological functions.”

But other experts say the proposed project, which could cost tens of billions of yuan, is fraught with serious challenges.

Some argue that government planners have yet to identify a potential water source or sources, which in turn has raised questions about the project’s feasibility. An official at the Beijing Municipal Water Authority who asked to remain anonymous told Caixin that the government is still working out the details and has yet to set a timetable for the project.

Other experts wonder whether the city can afford the water network’s potentially astronomical price tag.

In 2002, the city spent 630 million yuan to renovate 3.7 kilometers of the Zhuan River, in the city’s west. Half of that amount was used to relocate people whose homes were in the project’s way.

Another 17 billion yuan worth of city funds went toward improving the 170 kilometer Yongding River, part of which flows through southwestern Beijing, in 2010.

The latest project’s announcement may seem oddly timed, since local water supplies have improved since the 500 billion yuan South-North Water Transfer Project started diverting water to Beijing from rivers in southern China in December.

From January to mid-May, the government said, the south-north network of pipes and canals diverted some 200 million cubic meters of water, meeting about half of Beijing’s demand. In addition, more than 10 million cubic meters of diverted water has replenished city reservoirs, lakes and canals.

Authorities said the interconnected system of “rings” would complement existing waterways in Beijing. The inner ring would stretch 20 kilometers, connecting several lakes and canals in central Beijing. A 60 kilometer middle ring would connect an ancient moat and canal system built in the 14th and 15th centuries.

The most ambitious – and costly – section of the project would be a waterway that encircles the entire city, stretching 230 kilometers.

An Old Idea

Beijing officials first considered a similar plan to build waterway rings in 1998, but did not tell the public, the Beijing Evening News recently reported. The plan came to light in 2002, when the Beijing Water Authority announced plans to spend 10 billion yuan on water system improvements that would nearly triple the amount of water available for household and business use by 2007. The plan included a long-term proposal to build waterways in three rings encircling the city.

In 2013, Zhang Tong, director of the authority’s Institute of Water, said that plan had been delayed because “the time wasn’t right” and “lacked detailed planning.” But he said the city was ready for the rings because “now we are more experienced.”

Since then, the city has spent 1.1 billion yuan on projects to improve the quality of its lakes and rivers. The effort has improved water quality in the city’s core, but dirty waterways still prevail in suburban areas.

The lower reaches of the Yongding River, southwest of urban Beijing, have been dry for most of the past three decades. A 2002 project that transferred water to the river from rivers in neighboring Hebei Province eased the shortage, but only for a couple of years.

Another government project aimed at cleaning up the Yongding as well as the Chaobai River, northeast of the city, started in 2010 and is slated to be completed next year. Altogether, the government plans to improve some 1,460 kilometers of riverways.

Recycled Wastewater

Finding a reliable water source for the proposed ring system appears to be the project’s biggest challenge, several water experts said. Some experts have suggested recycling the city’s wastewater, already a tried-and-true practice in Beijing. The city recycled 860 million cubic meters of water last year, official data show. One expert who asked not to be named said that about 90 percent of all water in the capital’s lakes and canals, including city parks, is treated wastewater.

Many experts have warned that recycled wastewater can contain harmful pollutants left over from the treating household and industrial discharge. Letting this water flow into lakes, canals and rivers may put local groundwater at risk, they say.

One expert said recycled wastewater may be contributing to the overall deterioration of Beijing’s water quality. The city’s Environmental Protection Bureau said 46 percent of the city’s rivers and canals were polluted in 2014, up from 39 percent in 2012.

Zhu Chendong, a former water authority chief engineer, said the city should stop discharging treated wastewater into lakes and rivers in the city’s northwest, where groundwater is tapped for drinking. He also recommended that the city limit the amount of water channeled into Beijing’s scenic area lakes and canals.

Jia, of the CAS, said the ring system should build on existing waterways, rather than undertaking new developments. But due to urban growth, some of the city’s oldest waterways have already disappeared.

About 30 kilometers of waterways were buried or drained by development in the 1960s. And more than 800,000 square meters of lakes were filled in or covered over to make way for residential and factory buildings in recent decades.

Whether the ring system can improve water quality is subject to debate, said Wang Ke, an urban planning expert. Any manmade body of water that lacks access to the natural groundwater system can do little to improve the environment, he said. Most Beijing water projects involve laying impermeable material or concrete at the bottom so that canal water cannot seep into the ground.

Some experts have even warned that the ring system could increase environmental risks, since interconnectivity of the city’s waterways could allow pollution from one area to spread.