For three years, an unknown man had been leaving barrels of drinking water under overpasses for migrant workers and passers-by in Zhengzhou, Henan province.

Li Laofa uses a water distiller to fill barrels with water at his home in Zhengzhou, capital of Central China's Henan province, on Aug 19.

Unloading them from his battered, old car, the man has shunned attention and left silently.

"We are very grateful for what he has done," said Hou Haiyan, a 46-year-old migrant worker. The workers often do not finish until midnight and by then shops are closed, but they can always rely on the barrels of water.

"Sure it's helpful for us, especially when the weather is hot," added Hou's 50-year-old colleague Shen Xueyi.

"The gift itself may be small, but it's the time and energy he has spent that moves us," Shen said. "He sticks to it even in bad weather. He's an example for all of us."

The mysterious man bearing watery gifts had remained out of the spotlight - until now, when the media picked up on his story.

Even then, he tried at first to deny he was the man on TV.

"Well, I'm just doing a trivial thing, and it's not worth mentioning," said Li Laofa with a shy smile.

The 50-year-old landscape gardening contractor said that he decided to help out after seeing so many migrant workers at construction sites drinking tap water when they got thirsty. They often gathered under the overpasses at noon and stayed there for the night to save money.

"I know how hard their lives are," said Li, who was a migrant worker when he arrived in the city 22 years ago. "I thought at least I can get them some clean water, even if I can't do much more."

He began by buying a second-hand water dispenser and put two barrels of water on it. However, the barrels would be empty before noon, and a crowd would come as he replenished them.

"When I saw that, I realized this is important," Li said. However, he couldn't afford to keep buying water, so he purchased a distiller for 3,200 yuan ($500) in 2009 and gradually increased the number of places he was leaving water.

"I must make sure they have water anytime they want," said Li.

During the hottest days in mid-August, he had to make up to 70 barrels of distilled water a day at his 200-sq-m apartment.

The distiller, which produces one barrel in 20 minutes, had to work around the clock for three days, and Li's family had to take turns looking after it in case it overflowed.

Li, the sole breadwinner in the family, earns more than 100,000 yuan in a good year from doing several gardening projects. However, he hasn't worked much since last autumn because he "felt tired and fell ill". The family has lived on borrowed money for months this year.

"We even don't have money to buy necessary things for our children, and the first thing he did was buy 60 new barrels with 1,000 yuan and open two new free-water sites as soon as he received an advance payment two weeks ago," complained his wife, Li Haixia.

"But I understand him. He's doing a good thing," she added.

Other than the financial difficulties, the occasional thefts of his barrels hurt him.

"I thought about giving up, but that was just for a moment," Li said.

Carrying so many heavy barrels out of the apartment building is not easy, and he is covered in sweat before he even gets them all in the elevator.

One neighbor surnamed Chen sometimes shows her respect for Li by giving him a hand when she sees him moving the barrels.

"He serves others spending his own money, and doesn't want to make it public," she said.

Li estimated that more than 1,000 people are served with his free water every day.

Some bus dispatchers and street cleaners have volunteered to look after the empty water containers, and collect them to avoid theft.

"We knew what he was doing for a long time, but we just didn't know his name because he wouldn't tell us," said Du Junzhi, 40, one of the bus dispatchers. "He's a nice guy, and has been helping others for so long. We're just doing what we can to help him."

Since his story became public, many people have come to help him when he changes the barrels. Some have donated money and bought T-shirts and cups for migrant workers.

Even Li's business partner and friend, Yang Haiping, didn't know Li's story before it was reported on TV. He donated 5,000 yuan.

Yet Li does have bigger dreams, including renting some shelters for those migrant workers.

"I must work hard, and maybe I will be able to set up free water points in many other cities," said Li.