Do bathing caps help your pool water?

What chlorine binds to in the water

Chlorine does its job in pool water by killing germs, but it does not work alone against everything swimmers carry in. When chlorine binds to the body waste that people bring into the water, things like sweat and other residues, the binding reaction can produce chemicals known as chloramines.

Chloramines belong to a category called combined chlorine. They form in the water first, and from there they can leave the water and pass into the air sitting just above the surface. That move from water to air is what sets up the problems swimmers notice.

While the chloramines stay dissolved, they can irritate the skin and the eyes. Once they turn into gas above the water, they can also bother the respiratory tract, the nose included, and this tends to be especially noticeable in indoor pools, where the air above the water does not disperse as readily. So the same chemistry that starts in the water can follow a swimmer up into the air they breathe.

The CDC places bathing caps in the prevention steps

The Centers for Disease Control and Prevention lists wearing a bathing cap among the steps swimmers can take to keep pool water clean. The reasoning is straightforward: anything that comes off a body and into the water becomes something the chlorine has to deal with. A cap keeps hair, and the dirt and products clinging to it, out of the pool, which means less material for the sanitizer to break down.

Alongside the cap, the same guidance asks swimmers to wash off before getting in, to stay out of the water when they have diarrhea, and to never urinate or defecate in the pool. Each of these habits removes a source of contamination before it can enter the water in the first place.

A bathing cap will not do the job on its own, but as one habit among several, it lightens the load on the water.

Why the cap works with a rinse

A bathing cap does part of the work, but what a swimmer does before stepping into the pool matters just as much. A rinse off before swimming is worth requiring of everyone who plans to get in, and that includes household guests as much as family members. The habit is simple enough that it should not feel like a burden.

The reason a quick rinse shower helps is that it washes away a good share of the body waste that would otherwise end up in the water and combine with chlorine. Once that waste is gone, there is less material available to form chloramines, which are the compounds responsible for the harsh smell and irritation around a pool. Sending everyone to the toilet before they swim handles the other common source of contamination.

Together, the cap, the rinse, and the bathroom trip form a routine that keeps the water easier to maintain.

What chloramines do above the water

When chlorine binds to contaminants in the water, it can form chloramines, and some of these eventually leave the water as a gas. Unlike ordinary air, chloramines weigh more, so instead of drifting up and away they tend to settle in a layer right above the surface. Swimmers breathe through this zone while they train or play, and spectators seated close to the pool breathe it too, which can lead to negative health effects for both groups.

The situation gets worse if the space around the pool is not properly ventilated. Without good air movement to carry the fumes out, chloramines keep building up in the air over time, and the quality of the environment steadily declines for everyone spending time there. That includes swimmers in the water, spectators on the deck, and the staff who work at the facility day after day.

This is part of why the air above a pool matters as much as the water in it.

Keeping the level in check

Combined chlorine is the number worth watching. To find it, take the total chlorine reading and subtract the free chlorine reading. Whatever is left over is the combined chlorine, the portion that has already been used up binding to contaminants in the water.

Health departments in most cities, counties, and states set a ceiling for combined chlorine at 0.4 ppm or less. If the calculation comes in above that line, the water needs attention rather than a simple top-off.

Checking this figure on a regular basis tells you when treatment is necessary, since the combined number will drift upward as chlorine gets tied up with whatever swimmers and the environment introduce. Watching the level and treating the water when it climbs keeps the pool within the limits that local health authorities expect.

Next step: water testing and chemistry service.

Sources

• Centers for Disease Control and Prevention: Chloramines and Pool Operation

Where Sullivan’s works

Sullivan’s Pool Service maintains pools in and around Austin, including Northwest Hills, South Austin, West Lake Hills, Tarrytown, Great Hills, River Place, Crestview, East Austin, North Austin, West Campus, Hyde Park, Downtown Austin and St. Johns, and in Bee Cave, Cedar Park, Georgetown, Leander, Pflugerville and Round Rock. See every service area.

Weekly residential service has one fixed monthly price, set by pool size: see pool service pricing for what each size tier covers.