Every studio owner knows the numbers on the recovery side of the building. The shower runs at 105. The hot tub is set to 104, because that is the ceiling the Consumer Product Safety Commission recommends. The steam room sits somewhere around 110. The cold plunge is the outlier at 45, and it is the outlier for a reason.
Put those numbers next to one more. The Centers for Disease Control and Prevention describes Legionella, the bacterium behind Legionnaires’ disease, as growing best in warm water between 77 and 113 degrees Fahrenheit. Read the studio numbers again. The shower, the hot tub and the steam room all sit inside the band. Not near it. Inside it, for every hour the building is open and most of the hours it is closed.
That is not a reason to shut the wet area. It is a reason to understand what the organism needs, where in a studio it finds it, and which of those places belong on a cleaning contract.
What Legionella needs, and where a studio provides it
Legionella does not thrive in clean water moving through a pipe. It thrives in biofilm, the thin slime that forms wherever water sits against a surface long enough for bacteria to settle and build a matrix. Scale and sediment make the film thicker and give the organism something to hide in. Warmth speeds all of it up. Stagnation seals the deal.
Now map that onto a studio. Inside a shower head, water sits warm between uses and the fine passages collect scale. On steam room tile, condensation runs down the wall and pools in the grout lines, which are porous and never fully dry. In the floor drain and the drain line below it, warm water and soap residue sit for hours. Around a hot tub’s jets, fittings and skimmer, film forms where the chemistry has the hardest time reaching. Every one of those sites is warm, wet and undisturbed for long stretches, and every one of them is a surface rather than a volume of water.
The CDC lists hot tubs, showerheads and sink faucets, cooling towers, decorative fountains and large plumbing systems among the places Legionella grows and spreads. People contract the disease by breathing in small droplets of water that contain the bacteria, which is exactly what a shower, a steam nozzle and a bubbling hot tub produce. About 1 in 10 people who contract Legionnaires’ disease die from it, per the CDC, and the risk rises for people over 50, for smokers, and for anyone with a chronic lung condition or a weakened immune system. That last group includes a meaningful share of the people who join a recovery-focused studio in the first place.
Whose job is which
The industry framework for this is a water management program, the approach laid out in ASHRAE Standard 188 and walked through in the CDC’s toolkit for building owners. It asks the operator to map the water system, identify where Legionella could grow, set control limits such as temperature and disinfectant level, monitor them, and document it. Hot tub chemistry lives here. So does flushing fixtures that sit unused, keeping the water heater hot, and testing the water when a control limit is missed. None of that is a cleaning company’s job, and a cleaning company that claims it is doing your water management is telling you something worth questioning.
The cleaning company’s job is the surface side of the same problem. Biofilm grows on surfaces. Scale builds on surfaces. The step that physically removes both is cleaning, and it is the step every downstream control depends on, because a disinfectant applied over scale reaches the scale, not what lives under it. In practice the surface side means shower heads and hoses, steam room walls, benches, floors and grout, floor drains and their covers, the hot tub surround and its visible fittings, and the fixtures in between.
Here is the gap. Most studio cleaning scopes we read in Columbus handle the entire wet area with a line like “wipe down showers and steam room.” No surface list. No descaling schedule. No mention of drains. No product named, and no contact time. A crew following that scope to the letter will leave the shower heads alone, because nobody told them to touch a shower head, and will wipe the steam room bench in the twenty seconds the line implies. The scope was written for an office, and the wet area is not an office.
Five lines a wet-area scope needs
The fix is written, not scrubbed, and it fits on one page.
Name every wet-area surface. Shower heads and hoses, steam room walls, bench, floor and grout, floor drains and covers, the hot tub surround, jets and fittings within reach, the door handles and the wall-mounted dispensers. If a surface is not on the list, it is not in the scope.
Schedule descaling. Central Ohio water is moderately hard, and scale is the shelter biofilm grows in. Shower heads get removed and descaled on a written interval. Steam room tile and grout get a descaling product on a written interval, not when the white haze becomes obvious.
Clean before you disinfect. Soil and scale come off first with the right product and real agitation. Then the EPA-registered disinfectant goes onto a clean surface. Every disinfectant label assumes this order, and skipping the first step spends the second one for nothing.
Hold the contact time. The label states how long the surface must stay wet for the claim to apply. On a warm steam room wall a spray dries fast, so the crew has to know the number and keep the surface wet until it is met. We have written about why that clock does not negotiate and about what it looks like on a studio floor.
Name how the work is checked. Who verifies the shower heads came off this month, what the check looks like, and where the record lives. A scope without a check is a wish list.
How we check it
We do not test for Legionella. That is a water sample sent to a laboratory, and it belongs in the operator’s water management program. What we verify is the cleaning step, with ATP readings taken on site and shown to you. ATP measures organic residue, the film that organisms grow in, and a low reading on a shower wall, a bench edge or a drain cover after service tells you the surface was actually cleaned rather than visited. A high reading the morning after tells you where the scope is failing. It is a cleaning-verification measure and does not speak to disinfection, to Legionella, or to the water itself, and we will never say it does.
What it does do is close the loop the scope opens. The five lines above say what should happen. The reading says whether it did.
The one-sentence version for your studio manager
Legionella grows between 77 and 113 degrees, our whole wet area sits in that range, the operator owns the water and the cleaning contract owns the surfaces, so the contract needs a surface list, a descaling schedule, a named product with its contact time, and a check.
Frequently asked questions
At what temperature does Legionella grow?
The CDC puts the preferred growth range at 77 to 113 degrees Fahrenheit, about 25 to 45 Celsius. Below that band growth slows sharply, and above roughly 122 degrees the organism begins to die, which is why water heaters are set hot and why the warm middle of a building’s plumbing is where problems start.
Where does Legionella live in a fitness or wellness studio?
In biofilm and scale, not in clean flowing water. The usual sites are inside shower heads and hoses, on steam room tile and grout, in floor drains and drain lines, around hot tub jets and fittings, and in any fixture or dead leg that holds warm water for hours at a time.
Is Legionella the cleaning company’s responsibility or the studio’s?
Both, in different places. Water treatment, hot tub chemistry and the water management program belong to the operator. The surfaces the biofilm grows on, shower heads, tile, grout, drains and fittings, belong to whoever cleans the building, and that work only happens if the cleaning scope names those surfaces, schedules descaling and carries a contact time.
Does cleaning a steam room with a disinfectant kill Legionella?
A disinfectant works on a clean surface for its labeled contact time. On a surface coated in scale or biofilm the product cannot reach what it is meant to kill, so the cleaning step, removing soil and scale first, is what makes the disinfectant step count. Neither step replaces the operator’s water treatment.
Can ATP testing detect Legionella?
No. ATP testing measures organic residue on a surface and does not detect Legionella or any specific organism. A low reading after service shows the cleaning step removed the film that organisms grow in. A high reading shows the surface was skipped or only visited. Testing for Legionella itself is a water sample sent to a lab.
Sources
- Centers for Disease Control and Prevention. Legionella (Legionnaires’ Disease and Pontiac Fever): Causes, How it Spreads, and People at Increased Risk. Growth range 77 to 113°F; sources including hot tubs, showerheads and faucets; case fatality about 1 in 10.
- Centers for Disease Control and Prevention. Developing a Water Management Program to Reduce Legionella Growth and Spread in Buildings: A Practical Guide to Implementing Industry Standards (based on ASHRAE Standard 188).
- ASHRAE Standard 188, Legionellosis: Risk Management for Building Water Systems.
- U.S. Consumer Product Safety Commission. Spa and hot tub safety guidance, maximum recommended water temperature 104°F.
- United States Environmental Protection Agency. EPA-registered disinfectant label requirements for pre-cleaning and contact time.