How do we control humidity and chlorine odor at our HOA indoor pool?

By OurHOA · General information · Revised October 26, 2026

How an HOA board keeps indoor pool humidity at 40 to 60 percent, clears chloramine odor, runs the air handler year-round, and stops condensation damage.

Part of the HOA board handbook: vendors, projects and upkeep.

What good indoor pool air looks like

A strong 'chlorine' smell in a pool room almost never means too much chlorine. It means chloramines, the compounds chlorine forms when it reacts with sweat, urine and skin cells, and some of them leave the water as gas and hang over the surface. Three numbers keep an indoor pool comfortable and keep the building dry: combined chlorine at or below 0.4 ppm, relative humidity between 40 and 60 percent, and room air a couple of degrees warmer than the water. You get there by keeping the water clean, bringing in outside air and pushing pool air out across the water surface, and running the dehumidifying air handler the way its designer intended, all year. Pool rules vary by state, by county and by your governing documents, so treat this as general education, not legal advice.

Why the room smells and people start coughing

The CDC says chloramine buildup in indoor pools is common in winter, when operators cut back on outside air to save on heating. A December 2006 case in Nebraska shows how that goes wrong. At a motel's indoor pool, 24 guests got sick with burning eyes, coughing, wheezing and shortness of breath, and a 6-year-old spent a night in intensive care. Investigators found the pool room's one ceiling exhaust fan switched off and the windows shut against the cold. Combined chlorine measured 4.2 ppm. The pool's own logs showed combined chlorine out of range for 26 days in a row before anyone acted. The lesson for a board is plain: the log usually shows the problem weeks before an owner complains, so someone has to read it. The same three causes are worth checking at any community pool: a closed outside-air damper, a fan or air handler turned off to save money, and water that nobody rebalanced.

What state rules require of an HOA indoor pool

Texas treats a pool run for a property owners association, condominium or apartment complex as a Class C pool under 25 TAC 265.182. The water rules in 25 TAC 265.193 cap combined chlorine at 0.4 ppm, ban cyanuric acid and stabilized chlorine such as dichlor in any indoor pool, and require a Class C pool without on-site pool staff to test and log disinfectant and pH at least once a day. Logs must be kept at least three years and produced to the health authority within five business days if they are not kept on site. Florida's statute sorts association pools by size. Under Fla. Stat. 514.0115(2)(a), a pool serving no more than 32 condominium or cooperative units, and not run as a public lodging establishment, is exempt from supervision except for water quality. A condo or co-op pool serving more than 32 units, whose recorded documents bar rentals under 60 days, still needs plan approval and an initial operating permit and gets an annual inspection for water quality and lifesaving equipment. Subsection (3) exempts a homeowners association with no more than 32 units or parcels, except for water quality and the anti-entrapment drain safety rules in s. 514.0315. Colorado's pool statute, C.R.S. 25-5-809, does not apply to a pool attached to a single-family dwelling, condominium or apartment house that is used only by residents and their guests. Whether your subdivision clubhouse pool fits that wording is a question for your county public health agency and your attorney. In all three states, the rules deal mostly with water. For air targets, boards rely on the CDC's Model Aquatic Health Code and the original mechanical design.

Set the targets and check them every week

The annex to the CDC's Model Aquatic Health Code accepts relative humidity of 40 to 60 percent and says the air handling system should hold it below 60 percent while people are using the pool. Below about 50 percent, the water evaporates faster, which costs you in refill water, chemicals and heat. For air temperature, use the design specs if you have them. The annex's worked example pairs 82-degree water with 84-degree air and says to raise the air one degree if you raise the water one degree, to keep evaporation steady. Buy a calibrated digital humidity meter and take readings at three spots around the deck, then average them. For the water, combined chlorine is total chlorine minus free chlorine, so your test kit has to measure both. The annex also notes that keeping pH below 7.5 makes chlorine work harder, so you need less of it. Put one line a week in an air log next to the water log: date and time, humidity at each spot, air and water temperature, free and total chlorine, combined chlorine, whether the outside-air damper is open, any odor, and initials.

Run the air handler the way it was designed

The dehumidifying air handler is the piece of equipment a well-meaning volunteer is most tempted to turn down when the gas bill arrives. Settle these points with your service contractor and write them on a card in the mechanical room. Do not shut off space heat or the air handler for the season while the pool holds water. The MAHC annex explains why: a colder room makes the pool evaporate faster, and that moisture condenses wherever it finds a cold surface. Keep the pool room at negative pressure relative to the rest of the building, so pool air does not leak into the clubhouse, gym or offices. Confirm the outside-air damper actually opens. The CDC tells operators to move fresh air across the water surface toward the exhaust vents and send chloramine-laden air outdoors, even though heating that outside air costs money. Change filters on the schedule the manufacturer sets, and shorten the interval if they come out fouled. Check the condensate drain pan and keep any P-trap filled so sewer gas cannot get into the ductwork. Hire a contractor who services pool dehumidifiers, not only general HVAC. The CDC suggests asking the equipment's technical representatives how to get the most chloramine removal at the lowest heating cost. Ask for the design setpoints in writing at the first visit.

When the smell comes back

Work through it in this order. First, test free and total chlorine and work out the combined number. If combined chlorine is above 0.4 ppm, close the pool, open up the ventilation, and follow the CDC's breakpoint method: raise free chlorine to 10 times the combined chlorine level, then bring it back down to the normal range before you reopen. Second, check the damper, the exhaust fan and the air handler's mode. Look for a timer or thermostat change made when the weather turned cold. Third, go after the source, which is what swimmers bring into the water. The MAHC annex cites research finding that a shower before entry cut the organic load in the pool by 35 to 60 percent, with showers lasting only 17 seconds. A sign by the pool entrance can say: 'Please rinse off in the shower before you swim. Sweat, lotion and urine in the water are what cause the chlorine smell and the sting in your eyes. Use the restroom before you get in. If the air smells strong or bothers your eyes or breathing, leave the pool area and call [contact name and number].' If several people report burning eyes or coughing, close the pool, air out the room, and call the local health department. When the system comes up for replacement, the CDC notes that UV or ozone systems can also reduce chloramines; get the engineer's opinion on adding one.

Condensation is the slow, expensive problem

Condensation can damage the building for years before anyone sees it. The MAHC annex warns that any surface that cools below the room's dew point gets wet, including surfaces inside a wall, and it recommends at least one inspection during the first heating season to find them. Windows are a common trouble spot. Once a year, walk the room with your contractor and look for rust on steel roof decking and door frames, peeling paint, stained ceiling tiles, wet insulation and black spots in corners and on window frames. If you find mold, our guide on responding to mold in HOA common areas covers cleanup and when to call a professional. Ask your reserve study provider to list the pool air handler as its own component, with a replacement cost from a real quote rather than a guess.

Mistakes boards make, and a motion to adopt

The usual mistakes: turning off the air handler or heat for the winter to cut the utility bill, closing the outside-air damper because the room feels cold, reading only free chlorine and never calculating combined, using stabilized chlorine in an indoor pool, treating humidity as the landscaper's or the pool vendor's problem when neither is under contract for it, and learning the dehumidifier failed when the ceiling drips. If the health department does close the pool over water or air quality, our guide on what to do when the health department closes the HOA pool walks through the reopening steps. A motion the board can adapt: 'Move that the board adopt the indoor pool air log, set operating targets of 40 to 60 percent relative humidity, room air about 2 degrees above water temperature or as the design specifies, and combined chlorine at or below 0.4 ppm; keep the pool air handler and space heat running year-round while the pool holds water; and authorize the president to sign an annual service agreement for the pool air handler not to exceed $____.'

Sources

These guides are general education for HOA boards and residents, not legal, tax, or financial advice. Rules vary by state and by your community's governing documents - check with a professional for your situation.

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