San Francisco (CNN) Five years ago, Doniece Sandoval gained a new perspective on San Francisco's immense problem of homelessness. It happened in her own neighborhood.

"There were three elderly gentlemen, all in their 80s, who we watched, one by one, get evicted," she said. "They began to live in their cars, had their cars repossessed, and ended up on the street."

As the Bay Area bounced back from the economic recession, Sandoval saw rents skyrocket. Diverse areas in and around San Francisco became gentrified, trendy -- and pricey. And as tech companies and other businesses moved in, lower-income residents were forced out.

Sandoval saw more and more people living and sleeping on the streets. And all of them, she said, were struggling with hygiene. When she learned there were fewer than 20 shower stalls and toilets for thousands of homeless individuals, she was shocked.

"For the homeless community, it was the equivalent of being in a third-world country," she said.

Then she came across an article about the city's plans to replace old public buses. It gave her an idea.

In 2013, Sandoval obtained and began converting retired city buses into mobile shower units. Her nonprofit, Lava Mae, has since provided more than 20,000 showers to more than 4,000 homeless individuals.

"People come out after showering, sometimes they're crying, sometimes they're ecstatic, sometimes they ... hug us. And it's incredibly humbling to see that level of gratitude for something that should just be a basic human right," Sandoval said.

Today, the organization -- whose name is a play on the Spanish translation of "wash me" -- relies on commercial shower trailers, providing 30-to-50,000 showers a year.

The group has expanded its services to Los Angeles and Silicon Valley and plans to release a toolkit this month to help other communities create this service.

CNN's Allie Torgan spoke with Sandoval about her work. Below is an edited version of their conversation.

CNN: How has the Lava Mae project evolved?

Doniece Sandoval: Last year, to increase our efficiency, we decided to switch to the mobile commercial shower trailer unit so that we could get them out there faster and meet need more effectively. We've got two mobile units in San Francisco, one in Silicon Valley, and we have our two buses. Last November, we opened our branch in Los Angeles in Venice Beach and downtown L.A.

Guests sign in and are put on the list. And then when you are called, you are given fresh towels, toiletry products and a hygiene kit. When we can, they include socks, toothbrush, toothpaste, deodorant, razors. In a six-hour period, we provide anywhere between 42 and 48 showers per unit.

We have seen people who haven't showered in months, and to get in and take a shower for the first time has completely changed their lives. It's really beautiful, and heartbreaking, to witness that transformation.

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CNN: Who are the guests accessing your services?

Sandoval: We see a really unique cross-section of people. We see people who are actively looking for work. We see people who have jobs, sometimes up to two jobs, but they were evicted and can't get back in to housing here. So, they're living in their cars, or they are couch surfing, or they're living on the streets.

We see elderly people; we see young families, where one or both parents might have gotten sick or lost their job, got evicted. It's this delicate balancing act where the slightest change in fortune puts them on the street.

We do see people who are chronically homeless; they've been homeless for over a year. Many of them haven't given up hope, and they have a tremendous sense of resilience.

CNN: And your group's support goes beyond showers.

Sandoval: One of the things we saw pretty quickly was, the way that you treat guests is actually even more important than the service you provide. We learn their names; we learn their stories. We provide all this extra support. It's creating community around them. And we call that "radical hospitality."

We want to be able to make sure people can access other services like medical care or case management. Our pop-up care villages are Lava Mae at its best. We bring multiple providers to the street to increase access to services -- everything from haircuts and clothes to dental, medical and legal services.

Lava Mae has provided more than 20,000 showers. Randy, left, is a client-turned-volunteer.

CNN: You also embrace the transgender community and others who might fall through the cracks.

Sandoval: It's hard enough just to be homeless, but if you are trans, it's very likely you may not have received any acceptance in your home. You are, even here in this very progressive city, a target for ridicule and scorn and violence. It becomes innately more difficult.

The idea is that you show up, we welcome you. We don't discriminate ever on the basis of culture, color, race, sexual orientation, nothing. As a matter of fact, on the bus you'll see there's a male, female and a trans sign, and there's also a wheelchair.

It's very important for us to be able to absolutely welcome everyone. Our idea is just to open our arms.

Want to get involved? Check out the Lava Mae website and see how to help.

To donate to Lava Mae click the CrowdRise widget below.