San Francisco Mayor London Breed wants the city to open safe drug injection sites. She also wants city residents to feel the facilities don’t have to be a danger or a nuisance.

So on Sunday, she’s expected to talk about her plan to open a demonstration injection site meant to provide the public with a realistic sense of what such a facility would look like.

Breed plans to make the announcement during Sunday services at Glide Memorial Methodist Church in the Tenderloin, where the mock safe injection site will be housed and open to the public next month, from Aug. 28 to 31.

The model site, Breed said, represents a way to allow people to learn about safe injection facilities by making one tangible, bringing it out of the realm of abstraction. Proponents of safe injection sites also hope the model will dispel the notion that the sites enable drug use.

“It’s one thing for people to hear about it, it’s another thing for them to see it,” Breed said. “I want to convey to people that it’s not that bad. People are going to shoot up, and we don’t have control over that. But there’s a way to control it, there’s a way to get it indoors so it’s not impacting our streets in a negative way.”

The model site is still being designed, said Glide spokesman Robert Avila, but it’s expected to draw on common features of existing facilities in other countries, including booths where drug users can inject drugs, to shoot up, as well as so-called “chill rooms,” where users can ride out their highs under clinical supervision.

“While there’s an amazing amount of support already in place for these kinds of facilities, there’s still a need to bring in the community as a whole, and that’s why we support a project like this,” Avila said.

Anyone wanting to visit the site is encouraged to sign up online for a guided tour using the project’s website, www.saferinside.org.

In addition to providing a clean place to use drugs, the facilities would feature a range of on-site services, like addiction treatment and medical care, as well as access to housing resources for people living on the streets.

“It’s about getting people off the street, from shooting up publicly and getting needles off the streets,” Breed said. “These places provide a location for people to be when they’re going through what they’re going through after they shoot up.”

Intravenous drug users are also being invited to tour the model site and, perhaps, provide officials with guidance about what they’d like to see in a real facility.

“This is not just for the general public and politicians, it’s also for the drug-user community to come and look and give feedback,” said Lydia Bransten, manager of St. Anthony’s Dining Room, a charitable meal service, and co-chair of Safer Inside, which promotes and provides education on safe-injection sites. “It doesn’t work unless the drug users want to use it.”

Safer Inside is helping to coordinate the opening of the site, along with city officials, Glide and the Tenderloin Health Improvement Partnership.

Breed and other officials say they’re determined to make San Francisco the first American city to open a safe-injection site — they’ve existed in Australia, Canada and Europe for years — but critics maintain that the sites will do little to deter drug use from occurring.

“The reality is that what we’re enabling is people who use drugs to be able to access health care, and to be able to have a direct link to services that will improve their health, including recovery services and drug therapies,” Bransten said.

But even with support from San Francisco residents, opening a safe-injection site is still considered a violation of federal law, which could leave the city and any organizations involved in operating one vulnerable to prosecution. The risk of legal challenges presents perhaps the biggest hurdle to opening a functioning site.

“I’m hopeful that this demonstration project will help move our process forward so we can potentially get something open soon,” Breed said. “It’s really hard to say today, but this is something I care about doing and I’ll continue to work with ... the Department of Public Health and the city attorney to come up with a solution.”

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