Alberto Carrillo began the morning of March 27 in much the same way as he has for the past year, working as a public Pit Stop monitor at Eddy and Jones streets in the Tenderloin.

The start of his shift usually involves a fair bit of cleaning, hosing down a portable public restroom in one of San Francisco’s grittiest neighborhoods. But by the end of his day at 5 p.m., Carrillo, 31, had saved one life and may have saved another.

And on Thursday, dressed in a crisp yellow and black Pit Stop uniform and cap, and surrounded by his family, Carrillo was honored for his actions when San Francisco Mayor Mark Farrell presented him with the city’s Certificate of Honor.

Supervising a public toilet is an unglamorous and at times even dangerous job. But for people like Carrillo, who was in prison just 14 months ago for a crime he’s not yet ready to talk about, the Pit Stop program is a path toward his future. A future that doesn’t include prison, where he has spent a total of 17 years during several incarcerations.

“I went to jail, but it’s not something I want to put out there. I don’t want to have that as a memory,” Carrillo said. “I went in for something I’m not proud of that I did when I was young. I’m trying to leave the past in the past.”

There are 18 Pit Stop locations in nine neighborhoods around San Francisco. In addition to serving as public toilets, they also provide a space to dispose of needles and for getting rid of dog waste.

Around 11 a.m. on that day last month, after perhaps two or three Pit Stop patrons had come and gone without incident, a man entered the stall and stayed for about four minutes. Carrillo began to worry.

Injection drug users looking for a sheltered space to shoot up frequently seek out the restrooms, meaning monitors like Carrillo have to be on the lookout for potential overdoses.

“When somebody goes in the bathroom, it’s mandatory for us to double-check the time and log it in,” Carrillo said. He speaks slowly in a soft voice and occasionally cracks a boyish grin. “I said, ‘Hey, are you all right?’” The man inside said that he was.

Another two minutes passed. Carrillo called out again, but this time, the response he was hoping for didn’t come. He called out again, warning the man that he would be forced to open the bathroom door if he didn’t hear a reply. After six or seven tense minutes, Carrillo threw open the door.

“That’s when I saw him lying on the floor,” he said. “He was turning purple and his eyes were upside-down, so my reaction was to bring him out of the bathroom.” He dragged the man out onto the sidewalk. “My reaction was, ‘I don’t know what to do, but I’m going to pump his chest.’”

He had never administered CPR before.

“I was just trying to bring him back. I was just thinking, ‘Don’t die.’ I was actually telling him that. I don’t know if he heard me, but I was telling him not to die, that everything was going to be all right, and that the ambulance was going to be here.”

A passerby called 911 as the man appeared to be coming around. Carrillo held his head as he vomited. An ambulance arrived moments later, and Carrillo called his supervisor, Harvey Turner.

“His demeanor is pretty much what it is now — cool, calm and collected. That’s why we have him at that location,” Turner said, adding that Pit Stop monitors are placed in locations befitting of their personalities and skills. Overseeing a public toilet in the Tenderloin is not for the faint of heart.

Carrillo, Turner said, “doesn’t panic under pressure. He has good verbal skills — he just knows what to do in any given situation.”

Carrillo’s nerves — and his reflexes — would soon be tested again.

Just hours after an ambulance took the first man away, he noticed another staggering past his Pit Stop. Within seconds, the man slumped and began to fall head-first to the sidewalk. Carrillo dived to the ground to break the man’s fall, catching his head in his hands before it smacked against the concrete.

“I went right down,” Carrillo said. “I slid on my stomach, and he landed right in my hand. He didn’t hit as hard as he was going to. It was perfect timing.”

He stayed with the man and helped to calm him before flagging down a police officer, who took over caring for the man and radioed for an ambulance. The man was suffering from severe dehydration, city officials said.

“There are a lot of people that think, ‘Oh, you’re at the Pit Stop, you just stand there all day.’ But it’s work, and it’s dangerous too, at the same time,” Carrillo said. “Other than that, it’s pretty good.”

The Pit Stop program, which employs many former prisoners, is run by the Hunters Point Family organization and the city’s Public Works department.

“The more open doors, the better,” said Public Works Director Mohammed Nuru, who was on hand Thursday alongside Farrell.

“Thank you for your really heroic efforts,” the mayor told Carrillo, who has ambitions of eventually working for Public Works or at BART. “What you did exemplifies what every city employee is all about — going above and beyond your duty.”

After several rounds of applause and handshakes, Lena Miller, the co-executive director of Hunters Point Family, presented Farrell with a gift — a black and yellow Pit Stop uniform, just like Carrillo’s, “so when you walk around the Tenderloin, you have automatic street cred,” she said.

Dominic Fracassa is a San Francisco Chronicle staff writer. Email: dfracassa@sfchronicle.com Twitter: @dominicfracassa