Hotels operate public spas governed by strict health regulations, meaning water safety relies far more on continuous chemical management and filtration than on frequent draining. Unlike a backyard hot tub, the high temperatures and heavy use of commercial hot tubs require constant oversight to prevent the spread of recreational water illnesses.
Water Replacement Versus Continuous Sanitation
The integrity of a commercial hot tub is maintained primarily through a system of continuous sanitation and filtration, not just physical water replacement. Sanitizers like chlorine or bromine are automatically injected to neutralize contaminants introduced by bathers, such as sweat, oils, and microorganisms. The high water temperature causes disinfectants to dissipate quickly, making the continuous monitoring of sanitizer levels particularly important.
To ensure the destruction of pathogens, free chlorine levels are typically kept between 3.0 and 5.0 parts per million (ppm), or 4.0 to 6.0 ppm for bromine. The acidity or basicity of the water, known as pH, must also be carefully regulated between 7.2 and 7.8, because a balanced pH ensures the sanitizer can work effectively. A comprehensive filtration system runs constantly to physically remove suspended particles, hair, and debris from the water. This combination of chemical disinfection and mechanical filtration is the daily defense against bacteria that cause recreational water illnesses (RWIs).
Regulatory Oversight and Water Quality Monitoring
Public hot tubs in hotels and similar facilities are subject to health codes established by local and state authorities to ensure water safety. The core requirement is the frequent testing and recording of water chemistry.
For a commercial hot tub, staff must test the disinfectant and pH levels at least twice per day. During periods of high use, such as a busy weekend, testing may be required as often as hourly to ensure chemical levels remain within the safe, mandated range. These checks are documented and logged, creating a record that is subject to inspection by the local health department. This rigorous, multi-daily testing regime keeps the water safe between full-draining procedures.
Physical Draining and Refilling Frequency
Hotels do not change the hot tub water daily or even weekly; the timing is determined by water quality metrics that cannot be fixed by chemicals alone. The main factor driving a full drain and refill is the buildup of Total Dissolved Solids (TDS). TDS includes accumulated organic and inorganic matter, like minerals, body lotions, and chemical byproducts, which filtration and sanitation cannot remove.
As the TDS level rises, typically exceeding 1,500 ppm above the initial tap water level, the sanitizers become less effective, making it difficult to maintain a safe chemical balance. The frequency of draining is based on the tub’s volume and the “bather load,” or how many people use it. For a standard commercial hotel hot tub, this translates to a full drain, deep cleaning, and refill approximately every one to three months. This deep cleaning involves scrubbing the surfaces and purging the internal plumbing system before the fresh water is introduced.
Identifying a Properly Maintained Hot Tub
The average guest can look for several indicators to gauge the maintenance quality of a hotel hot tub before getting in. The water should be visibly clear, allowing a clear view of the bottom surface, even when the jets are not running. Murky or cloudy water is a strong sign that the filtration system or chemical balance is failing.
A properly maintained hot tub should have a very mild chemical smell, or no smell at all. A strong, pungent chemical odor indicates that the pH is unbalanced, which creates irritating compounds called chloramines. Visually check for a visible scum line around the interior perimeter of the tub, which suggests that oils and debris are not being properly filtered and removed. Finally, confirm that the jets and pumps are operating with strong, consistent pressure, as weak flow can indicate a clogged filter or a circulation issue.