Billy Howard/PBS Cheryl Morgan holds a photo of her father, who died after drinking dishwashing liquid in an assisted living facility in Georgia. Ms. Morgan is featured in a new PBS documentary, “Life and Death in Assisted Living.”
Assisted living underwent a big growth spurt in the 1990s as major corporations built and bought facilities, and almost ever since advocacy groups and researchers have been warning that however attractive these places look — chandeliered lobbies, pleasant individual apartments, the inevitable gazebo outside — the care they provide tends to be mediocre at best.

Many of these “communities” don’t hire or retain enough adequately trained staff to support their increasingly old and frail residents, who are not the active, silver-haired strollers depicted in brochures, but people typically in their late 80s with multiple health problems and high rates of cognitive loss. Critics have pointed out that unlike federally regulated nursing homes, assisted living facilities are governed by a hodgepodge of state laws; some provide decent oversight, while others remain quite lax.

So the hourlong “Frontline” documentary “Life and Death in Assisted Living,” airing Tuesday night on PBS stations across the country, doesn’t really break new ground on the subject. But it is important nonetheless.

One reason is that families, who make most of the decisions about assisted living, don’t pore over gerontology journals or state regulations as they are looking for a place that is not a nursing home.

So they don’t always realize that these reassuring-looking residences may have no nurse on the premises most of the time, that health care in assisted living frequently consists of a 911 call, that the average length of stay — according to the Assisted Living Federation of America — is less than two years.

For the average $3,550 monthly fee — a national average from a 2012 Metlife survey that conceals huge variations between, say, Montgomery, Ala., ($2,702) and Stamford, Conn. ($5,524) — families expect a final home full of attentive helpers. They may get that, sometimes. But they will learn from this documentary how vigilant they need to be.

A co-investigation by Frontline and the nonprofit news organization ProPublica (which will publish an accompanying story Tuesday), the film delves into several worst-case examples, making full use of the dramatic power of visual media.

In on-camera interviews, grieving relatives tell about the man with dementia who found industrial dishwashing liquid in an unlocked cabinet, drank it and died of burns to his lips, throat and esophagus, for which the state of Georgia fined his assisted living facility $601. And about a Mississippi woman with dementia who managed to pry open a window in her second-story apartment and jumped to her death. About a California woman with dementia — perhaps you see a pattern here — who suffered so much from pressure ulcers that when family members sued, a jury awarded them more than $22 million in punitive damages.

All these cases occurred in facilities owned by the largest American assisted living chain, Emeritus, several of whose former staff members and executives acknowledge that the facilities took in residents too sick for assisted living, that the staffing was inadequate and that people were assigned jobs for which they hadn’t been properly trained.

It is true that with roughly a million elderly people in such facilities, many very old and in poor health, tragedies will inevitably occur. But pressure to keep apartments filled, labor costs low and shareholders happy increases the likelihood.

When families enter this zone, therefore, they can’t be lulled by the chandeliers. Assisted living remains a reasonable option for people who can’t manage their own households any longer, who need help with personal care, but who aren’t so ill that they require 24/7 nursing.

But given the lack of inspections or regulations with teeth, residents will fare better if families carefully monitor their condition and step in when necessary. “Life and Death in Assisted Living” helps to explain why.