Oscar Diaz says the smell of garbage “is so strong, we have to deodorize our room constantly.” Chronicle photo by Chris Hardy

Santa Isabel German tips back the lid of a heavy iron pot to reveal the source of the tantalizing aroma that fills her room.

It’s a stew of chicken, tomatoes, chiles, cilantro — the same caldo de pollo she once simmered on the stove in her native Honduras.

These days, German cooks for her three sons — ages 10, 15, and 18 — on a hot plate in her room at the Hurley Hotel in San Francisco. At dinner time, the boys troop downstairs from their third-floor room and find a place to sit on the edge of her double bed or couch.

The family is one of many who have made a home out of a room — or two — in a residential hotel in the city.

It’s a trend that worries a task force of city officials and tenant advocates familiar with living conditions in the hotels, which are also known as single-room occupancy hotels, or SROs.

“What we know is that SROs are inadequate, inappropriate and risky places for families with children to live,” the task force said in a draft report released in December. “What we don’t know is just how many families with children are living in them.”

To find out, the task force will conduct a survey in March of hotels located in the Mission, Chinatown, Tenderloin and South of Market districts.

It will be the first time the city has tried to document the troubling phenomenon, said Gordon Mar, who represents the Chinese Progressive Association, a Chinatown advocacy group, on the task force.

Mar said the group expected to find thousands of families living in residential hotels.

As skyrocketing rents put apartments out of the reach of low-income families, hotel rooms have become the only affordable option for many people, he said.

San Francisco has 457 privately owned residential hotels with a total of 16, 441 rooms.

The task force report said the hotels often violate city housing codes. They are “typically dark, unventilated and overcrowded,” with floors covered with “tattered, dirty and smelly carpets.” The buildings are often located in distressed, high-crime areas.

“A family with three to five children may live in an 8-foot by 10-foot room, ” the report said. “For these accommodations, families may pay $500 to $1,000 a month.”

Mar said the buildings were never intended to house families.

“In Chinatown, they weren’t even meant for two adults,” he said. “They were created with single, male laborers in mind.”

In the first part of the survey, community activists will count the families living in each hotel. Then, 200 families will be interviewed, and asked the language spoken by adults; their source of income; the ages and sex of children; the names of their schools; and the age, sex and income sources of dependent adults.

Interviewers will also ask families to estimate the percentage of their income devoted to rent and food. And the question: What is holding you back from moving your family into a better housing situation — credit problems, eviction history, move-in costs, insufficient income or other factors?

Mar hopes the findings will spur city action to improve health and safety problems, which are widespread in hotels located in the four targeted neighborhoods, and highlight the need to build more affordable housing for families.

The task force report said families often shared unclean bathrooms, and were forced to live with lead, rodents, cock roaches, mold, garbage and sewage.

Residential hotels, the report said, are “among the most likely places where tuberculosis can be transmitted in San Francisco.”

The task force identified asthma as another health risk.

Its report said many families living in hotels had little money left for food once they pay rent. In some neighborhoods, there are no full-service supermarkets or produce stands where families can buy fresh food. They can’t keep food “safe” without refrigerators or containers to protect groceries from rodents and insects.

“All of the above leave families dependent on fast-food outlets which may meet caloric needs, but fail to provide the nutritional quality needed to enhance health and prevent infection and chronic diseases,” the report said.

German, 36, who sells linens, including the ruffled curtains she has hung in her family’s rooms, said hotel living presented unique challenges.

“I have to be very careful and keep the food covered,” she said while settling the lid on her chicken stew. “Sometimes, pieces of the ceiling fall down when I’m cooking.”

She also has to be on the lookout for cockroaches, which could be seen crawling on the wall and carpet.

German shares her room with a male companion, and the couple keeps a pair of pliers handy so they can turn on the water in the bathtub.

She said the hotel’s policy on visitors — “No visitors at all times!” says a sign in the lobby — meant that her children couldn’t play in their room with cousins or friends from school.

That forces the kids out onto the sidewalk in the Tenderloin, a neighborhood known for drug dealing and prostitution.

German’s 20-year-old daughter also lives in the hotel with her infant son and husband. The couple puts cotton balls in their son’s ears when he sleeps to make sure there is no space for a cockroach to crawl inside.

German’s three sons live near the third-floor garbage room, where trash is sometimes piled so high it spills into the hallway.

To get to their room, visitors were required to step around a trail of trash on the carpet.

“The smell is so strong, we have to deodorize our room constantly,” said Oscar Diaz, German’s 18-year-old son, speaking through a translator.

E-mail Kathleen Sullivan at ksullivan@sfchronicle.com and Justino Aguila at jaguila@sfchronicle.com.