After disability rights activists sued BART this week, alleging that the transit system’s elevators are filthy and often used as restrooms, The Chronicle put the allegations to a sniff test — and mostly found elevators that were fairly clean and not all that smelly.

BART did not exactly come out smelling like roses, though, even if one elevator did reek of the strong floral perfume of an earlier user. Chances are that people who use BART’s elevators regularly will encounter a puddle of pee, the unmistakable odor of urine, some litter, or worse.

A reporter visited five BART stations in downtown San Francisco and the Mission District several times, plus a handful of stations in downtown Oakland and Berkeley, over seven hours Wednesday evening and Thursday and Friday mornings. He stepped into elevators 52 times, taking a good whiff each time and looking around for the obvious signs the elevator had been used as a restroom.

Urine was noticed on five occasions — including a puddle on the street elevator at Powell Street Station and another in the corner near the door of the street elevator at 16th Street Mission Station. There was also a sprinkling of what appeared to be pee in the street elevator at Civic Center/UN Plaza Station and urine in the tracks that guide the platform elevator doors at Powell station as well as the street elevator at Montgomery Street Station.

Results of The Chronicle’s nonscientific survey shouldn’t be seen as an indication a problem doesn’t exist. BART officials, in fact, acknowledge that elevators are too frequently used as restrooms.

“People urinating and defecating on the system is unfortunately a very common problem,” BART spokesman Taylor Huckaby said. “It happens so frequently we’re always going out there to clean it up. If it’s urine or feces, we usually know about it in 10 minutes.”

While most of the elevators were urine- and feces-free, The Chronicle’s survey found the experience of riding them less than pleasant. As the disability rights groups pointed out in their suit, many are in out-of-the-way areas, around foul-smelling hallways and corners.

The waiting area for the elevator to the plaza at the 16th Street Mission Station, for instance, had the strong odor of urine on at least three visits, though there was none to be seen and the elevator itself was odor-free.

“They’re usually pretty clean,” said Charlie Bobb, 60, riding the street elevator at the 24th Street Mission Station. “They’re pretty good at keeping up with it. Hell yeah, I’ve seen urine in the elevators, but how are you going to stop that? Sometimes people have full bladders. You can only clean it up.”

All in all, BART’s San Francisco stations smelled more like a dingy basement locker room than an overused portable toilet.

BART officials say the relative cleanliness is no accident. Sanitation troubles in BART’s downtown San Francisco stations, including the elevators, have increased as the number of people living on the streets has risen.

BART has stepped up its elevator cleaning regimen. Supervisors conduct hourly inspections, crews perform routine and on-demand cleaning, and daily reports on elevator conditions are recorded. Signs have been posted in and around elevators asking patrons to tell station agents when cleaning is needed, and janitors are using an enzyme that promises to destroy the odor of urine rather than merely cover it up.

BART is also replacing elevator floors with an impervious gray rubber flooring that traps urine and keeps it from soaking into the plywood subflooring and dripping into the elevator pit, where it corrodes equipment and produces a pervasive and unpleasant smell.

Replacing flooring has taken some elevators temporarily out of service for extended periods, Huckaby said. The increase in out-of-order elevators was among the complaints in the lawsuit. The floor-replacement project is scheduled to be completed in May.

In a meeting in January with representatives of Disability Rights Advocates, one of the legal nonprofits that filed the suit, BART listened to the group’s complaints and explained what the transit agency was doing to improve the situation. BART cited a $16.3 million plan to improve the reliability of its elevators and $190 million in bond money from Measure RR that the agency is planning to put into its downtown San Francisco stations to improve access.

The meeting didn’t prevent the lawsuit, but BART officials say it shows they take complaints about filthy elevators and access for people with disabilities seriously.

“The thing we want people to understand is that this lawsuit did not catch us unawares or not dealing with the problems,” Huckaby said. “We have a long history of programs in place to make sure the impact on our disabled customers is as minimal as possible while we rehabilitate the elevators.”

Michael Cabanatuan is a San Francisco Chronicle staff writer. Email: mcabanatuan@sfchronicle.com Twitter:@ctuan