San Francisco officials are extending a pilot program examining the impact of keeping three public bathrooms open around the clock in neighborhoods where requests for feces removal really tend to pile up.

The extension is expected to build on the success of an experiment that began in August, when the city decided to keep three Pit Stops — public stalls with on-site staffers — open seven days a week, 24 hours a day.

As San Francisco confronts the growing volumes of human and animal waste showing up on sidewalks, officials have been under pressure to open more Pit Stops and to keep them open longer.

The pilot program, run by the Public Works Department, was meant to test whether bathrooms would be used in the small hours of the night, whether the investment in round-the-clock access would translate into cleaner streets and whether the people staffing the Pit Stops would be safe while on duty.

The past three months have shown promising results, according to Public Works data. More Pit Stops are imminent, and round-the-clock access at some appears highly likely.

For the city’s homeless, the Pit Stops have become places where people can relieve themselves with dignity. They’ve also transcended their function as public bathrooms: With an epidemic of injection-drug use, Pit Stop monitors have frequently stepped in to provide life-saving care to people who overdose in their stalls. Pit Stops also provide needle disposals and bags for picking up dog waste.

“This is not complicated — when people have access to a clean, safe restroom, they will use it,” Mayor London Breed said in a statement. “We have seen what happens on our streets when people don’t have a place to go, which is why I fought to include funding in the budget for seven new Pit Stops, as well as expanded hours at existing locations.”

Breed’s last budget included $8.1 million over the next two fiscal years to build seven more Pit Stops and expand hours at existing ones. The recently concluded three-month test cost $300,000 to staff the bathrooms around the clock. Two-thirds of that money came from Supervisor Matt Haney’s district budget. Two of the three 24-hour Pit Stops were in District Six, which he represents. There are now 25 Pit Stops spread across 13 San Francisco neighborhoods.

“Feces complaints are going up. Homelessness is going up. This is something that just flat-out makes sense, and something we can do right away,” Haney said. “And there’s some aspect of this you can’t measure in dollars, which is people’s human dignity and the basic access to restrooms that every human being deserves.”

The three locations selected for 24/7 service are at Eddy and Jones streets in the Tenderloin, Sixth and Jessie streets in South of Market, and Market and Castro streets in the Castro district. The Tenderloin location was the most heavily used over the past three months, with nearly 15,400 flushes. Nearly 25% of those flushes came between 11 p.m. and 7 a.m. daily, and the same held true for the two other locations: an average of 24.7% of all flushes came during the overnight hours.

The sight of people relieving themselves between cars on Eddy Street was an all-too-common sight for Mo Ali, manager of Downtown Grocery, which has no public restroom. He’d often shoo them away on smoke breaks.

“But now I just point across the street, ‘Go over there,’” Ali said. Since the Pit Stop started staying open 24-7, “I haven’t seen it like I used to. I used to see it all the time.”

At each location, Pit Stops were staffed by two attendants as a safety precaution. There were no reports of assaults during the three-month period.

Steam-cleaning requests sent through the city’s 311 system — for feces, urine or other debris — dropped at both the SoMa and Castro Pit Stops once the bathrooms switched to round-the-clock service, according to Public Works data that compared request volumes from May to October. The SoMa location saw 16 fewer requests after the switch and the Castro Pit Stop saw two fewer requests on average from August to October, compared with May to July.

Requests around the Tenderloin Pit Stop remained about the same during that time — a change of just 16.7 average requests from May to July and 17 from August to October.

Conditions have improved around the SoMa Pit Stop, said Fred Beasley, a security guard for Create Skateboard Shop on Sixth Street.

“It’s convenient — people have someplace to go now. They’re not in a doorway doing their business,” he said. But pet waste — and pet owners’ indifference — continues to be a problem, Beasley said.

“People need to be taking care of their dogs more. One step at a time, I guess.”

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