Authorities in Zhengzhou, capital of central China’s Henan Province, are to stop spraying tap water on roads as part of their clean air policy.

Officials say they will gradually replace tap with recycled after completion of the city’s drainage system, according to China News Service, with dusty areas vacuumed to save water.

Since April, sprinklers had been sent out every two hours during the day to dampen down roads and the CNS report said this had cost the city 35,000 tons of tap water a day, or more than 5 million tons so far.

The city has long had water supply problems as it relied on the often drought-stricken Yellow River, but this was relieved last December thanks to a south-north water diversion project.

However, its current overuse of water will lead to shortages again by 2020, said Wang Zhilu, deputy director of the Zhengzhou water supply office.

Urban management officials said spraying water on the roads was part of the city’s efforts to clean its air. But residents and experts both criticized the policy.

“I have been living in Zhengzhou for decades. I have never seen such huge water use,” resident Guo Yiwen told CNS. Another, Zhu Yonggui, thought it was just a face project and urged the government to plant more trees.

Shi Pu, a Henan University of Economics and Law professor, said the city was “treating symptoms instead of the root cause.”

Zhang Ruiqin, director of Zhengzhou University’s Institute of Environmental Sciences, said: “It indeed greatly decreases dust, but for haze, the effort is to no avail. More than a half of the toxic PM 2.5, which causes haze, evolves from other air pollutants and can’t be contained by simple watering.”

The south-north water diversion project brings water from the Danjiangkou Reservoir in the middle-upper reaches of the Hanjiang River, the largest tributary of the Yangtze, to Henan, Hebei, Beijing and Tianjin.