The Longgang Water Treatment Plant at an altitude of 1,150 meters. (Photo/ Yunyang County Water Resources Bureau)

Chongqing - At lunchtime on Sept. 5, every table at Nongxiangju, a restaurant in Longdong Village in Chongqing's Yunyang County, was occupied.

Owner Tan Yongjun moved between the tables serving dishes, a scene he once found hard to imagine during the summer months.

"Before, we worried about having too many customers," Tan said. "The water could be cut off halfway through cooking, and there was nothing we could do but watch the business slip away."

That is no longer the case.

While Tan's restaurant was serving a full house, several kilometers away, two water maintenance workers were climbing a mountain ridge with 5-kilogram tool bags on their backs. Their equipment included pipe wrenches, pressure gauges and a heat-fusion machine for repairing plastic pipes.

Their job is to keep water flowing to more than 50,000 people living in the mountainous Qingshui Tujia Township through the summer.

Pumping water uphill

Qingshui lies in a karst mountain region where steep terrain makes it difficult to store and distribute water. Seasonal shortages were once common.

A major change came with the county's integrated urban-rural water supply system.

Three reservoirs — Mabaoyuan, Dayangou and Xinmabaoyuan — now provide water for the system. Pumps lift raw water through more than 20 kilometers of pipelines to the Longgang Water Treatment Plant, which sits at an elevation of about 1,150 meters.

After treatment, the water is distributed through more than 100 kilometers of branch and household pipelines serving all 13 villages in the township.

Because some water sources are only about 750 meters above sea level, the system uses four stages of pumping to move water up the mountains. The highest stage sends it to a reservoir at 1,650 meters.

"The mountains determine how high we have to pump," said Wang Zhengbao of the Longgang Water Supply Center.

The system gained additional capacity in 2024 when the Xinmabaoyuan Reservoir was completed, adding 1.15 million cubic meters of storage. The project has helped Qingshui move away from its long-standing seasonal water shortages and brought rural and urban residents onto the same water supply network and quality standards.

Keeping the pipes running

For maintenance workers Nie Fei and Ran Jianjun, making sure that water reaches those communities means regular treks through steep and heavily vegetated terrain.

The two inspect their assigned pipelines every week. In summer, vegetation can cover parts of the paths, while steep slopes often require them to hold onto tree roots as they move forward with their equipment.

Pipeline leaks are among their biggest concerns.

On Aug. 31, a water pipe near the entrance to Qishan Grassland Scenic Area burst, sending a jet of water several meters into the air. Nie and Ran shut the valve, located the damaged section and repaired it using a heat-fusion machine.

The work took more than two hours under the summer sun. By the time the repair was completed, their clothes were soaked with sweat.

During the summer peak, maintenance teams also inspect pumping stations, power facilities and major rural pipelines to prevent failures across the multi-stage system.

Meeting a summer surge

The Longgang Water Treatment Plant has also stepped up operations during the peak season.

Daily water output has risen from about 900 cubic meters under normal conditions to more than 3,000 cubic meters during periods of high demand.

The water serves about 15,000 permanent residents of Qingshui, as well as restaurants, homestays and nearly 40,000 summer visitors.

Inside the treatment plant, water-treatment chemicals are continuously adjusted, while laboratories conduct more frequent tests of raw and treated water. Staff remain on duty around the clock and inspect reservoirs, pumping stations and elevated storage tanks every day.

"Once we entered the summer peak, we immediately activated our emergency plan for high temperatures and drought," said Ding Shengqian, director of the Yunyang County Water Resources Bureau.

The county is using real-time monitoring of reservoir levels and coordinated operation of multiple pumping stations to balance water sources across the network.

Since launching a 100-day campaign to strengthen flood and water-supply safety, the bureau has deployed 18 inspection teams across the county. So far, they have identified 216 risks, addressed 90 of them and introduced targeted measures for the remaining 126.

As evening falls, the lights come on at Nongxiangju. Inside, dinner is being served and soup simmers on the stove.

High above the village, water continues to move through the mountain pipelines from the 1,650-meter reservoir — a largely invisible system keeping homes, restaurants and businesses supplied through another hot summer.

(Li Jiayan, as an intern, also contributed to this report.)