An official audit has found 23 sewage treatment plants in east China's Zhejiang Province sitting idle, monuments to poor planning and mismanagement as wealthy but inexperienced authorities rush to build greening infrastructure.

The plants, which cost more than 780 million yuan (around 122 million U.S. dollars) to build, are either far too big for their catchment areas or are gathering dust as they wait to be connected to piping networks.

In Langya Town of Jinhua City, 13 million yuan was spent on a plant that has not been used since it was completed in 2010. Three of the four paper mills it was designed to cater for have closed down since its capacity was set. The remaining mill built its own sewage treatment plant.

"The current situation is very different from when this plant was designed," lamented Langya official Ni Yonghong

The town's 5,000 residents only produce around 600 tonnes of sewage per day, way below the plant's designed capacity of 5,000 tonnes. Operating it now would mean operating at a loss.

Xianyang Sewage Treatment Plant in Ningbo City faces a similar dilemma. It was designed to process around 10,000 tonnes of wastewater per day, but the actual discharge volume is only 3,200 tonnes.

"If we run it, we will lose money. Even not running it, our costs are 600,000 yuan a year," said Wang Chenghong, an official with Xianyang Town.

In addition to wildly inaccurate demand estimates, delays in building pipes have also postponed sewage works being put into use.

Owing to lack of funds, Ganlin Town of Shaoxing City has not been able to build pipes to the water treatment plant it built.

Tu Qiang, the town's Communist Party chief, has promised to finish the pipes before the end of November, four years behind schedule.

There has been a boom in China's sewage treatment industry over the past few decades as the government and public have gradually realized the importance of environmental protection. The central government has provided incentives and funding for plants' construction.

Urban China had more than 3,700 sewage works as of December 2014, around 1,000 more than in December 2010, according to the Ministry of Housing and Urban-Rural Development.

Plants standing idle is a nationwide problem, said Chen Tongbin, a research fellow with the Institute of Geographic Sciences and Natural Resources Research under the Chinese Academy of Sciences.

In 2008, south China's Guangxi Zhuang Autonomous Region set a target to have sewage treatment and refuse processing plants in all its cities and industrial zones by the end of 2010.

"We were too hasty trying to build so many treatment plants in such a short time," said Zheng Jiarong, executive vice chairman of the urban water association in Guangxi.

Like in Zhejiang, many of these facilities were badly planned, which has caused them to operate below capacity or sometimes not at all, added Zheng.