Indoor pools promise year-round recreation, yet many facilities wrestle with a familiar trio: eye and throat irritation, a stubborn “pool smell,” and rust that creeps across metal. The thread connecting these problems is chloramine buildup and the moisture that lets it attack steel, copper, and finishes. The fix is not mysterious. Tight control of dew point, paired with smart air distribution and steady pressure management, stops corrosion at the source and restores the room to healthy, clear air.
What is dew-point control, in plain terms?
It is the practice of holding the air’s moisture content to a specific target so water does not condense on cold surfaces. Relative humidity shifts with temperature and can mislead operators. Dew point is absolute. If the dew point sits below the temperature of windows, trusses, and ductwork, the room stays dry and corrosion slows to a crawl.
Why chloramines corrode
When disinfectant reacts with sweat and contaminants, it forms chloramines. These compounds off-gas right at the waterline and hug the deck. Left alone, they attack unprotected metals and irritate lungs. The answer is not endless dilution with outdoor air. Fresh air helps, but only if the system also keeps moisture in check, sweeps contaminants off the water surface, and keeps the natatorium slightly negative to hallways so odor does not spread.
Setpoints that work
A good starting strategy is simple. Keep room air a bit warmer than the pool water to reduce evaporation. Hold a moderate humidity band that balances comfort with corrosion control. Then convert that band to a dew-point target and let the dehumidifier control to it year-round. Do not chase seasonal guesses. Measure, set, and verify.
Below is a reference you can adapt with your design team:
| Scenario | Water Temp | Air Temp Target | RH Target | Notes |
| Leisure pool | 84–86°F | 2–4°F warmer than water | 50–60% | Comfort focused; watch glazing. |
| Competition pool | 78–82°F | 0–2°F warmer than water | 50–55% | Lower latent loads during events. |
| Therapy pool | 90–92°F | 2–4°F warmer than water | 50–55% | Extra attention to condensation risk. |
These are typical starting points, not codes. Your building envelope, glazing, and climate shift the safe dew-point number. Many projects also route reclaimed heat from the dehumidifier to space air or the pool water for steady temperature control.
Equipment and control features that matter
Modern natatorium units manage moisture by drying the air to the chosen dew point, then redirecting recovered heat where it helps most. Variable-speed fans trim airflow during off-hours and ramp for events. Intelligent outdoor air controls bring in the code minimum and more when air quality demands it. In dry, cold weather, systems may bypass mechanical drying because outdoor air alone can meet the dew-point target. In muggy weather, the dehumidifier carries the load and protects the envelope.
Many facilities invest in commercial pool dehumidification systems because they include these control modes out of the box and integrate with building automation. That integration only pays off if sensors are accurate, alarms are enabled, and operators actually review trend data. A monthly check of dew point, space pressure, and coil condition finds small problems before they become closures.
Air distribution and source capture
Moisture and chloramines rise from the pool but tend to linger over the water. The supply strategy should wash glass and exterior walls with dry air, then sweep the surface with a gentle, uniform flow toward low-level exhaust or gutter inlets. Ceiling returns alone let contaminants settle where swimmers breathe. Add targeted exhaust near the waterline and you will see fog and odor drop. Keep the room slightly negative to the rest of the building so the smell stays inside the natatorium until the system removes it.
Chemistry and HVAC work together
Perfect air will not overcome poor water chemistry, and perfect chemistry will not mask stale air. Coordinate testing, bather load management, and HVAC operation. Schedule backwashes and shock treatments when the room can run at elevated exhaust. Log both pool chemistry and dew-point trends in the same record. Patterns appear quickly when data sit side by side.
Commissioning and steady upkeep
New builds and retrofits succeed when commissioning is more than paperwork. Balance supply, return, and exhaust. Prove the negative pressure. Confirm airflow across the deck and glazing. Calibrate temperature and humidity sensors against traceable standards. Then hand the owner a clear seasonal playbook. That playbook should state filter cleaning intervals, coil wash schedules, and who to call when dew-point drift exceeds limits.
Warning signs and first fixes
What if the building already shows rust or a sharp odor? Start with measurement. Pull current dew point, space temperature, and water temperature. If the dew point sits near the surface temperature of metal or glass, raise the air temperature a notch or dry the air further to open a safe gap. Inspect for short-circuiting where supplies blow directly into returns. Verify that the exhaust near the waterline is actually moving air. Small corrections here often deliver fast wins before major capital work begins.
Teaming with the right partners
Natatoriums span architecture, chemistry, and mechanical engineering. Coordination matters. Pool operators handle water side care. Mechanical specialists tune the air side. Architects and envelope consultants guard against cold-surface traps. Experienced commercial heating companies can link boiler and air-side recovery so heat flows to the space or to the pool water with minimal waste. That cooperation keeps setpoints stable and energy bills predictable.
The simple formula
The science of indoor pool dehumidification distills to a short list. Hold a firm dew-point target. Move dry air across glass and the water surface. Capture contaminants low and exhaust them out of the building. Keep the space slightly negative to adjacent areas. Maintain chemistry and equipment with the same discipline you bring to the water itself. When these basics line up, chloramine corrosion fades, comfort returns, and the pool earns back its reputation as the cleanest room in the building.
If your facility needs a review or retrofit plan, partner with a contractor such as H & H Commercial Services who designs, services, and upgrades natatorium units along with the rest of the plant. Teams that deliver complete commercial HVAC installation and maintenance programs are best positioned to tune controls, verify airflow, and stand behind long-term results.