What are recreational water illnesses?
Recreational water illnesses, or RWIs, are infections you can catch from the water at pools, hot tubs, splash pads, lakes, and the ocean. They spread when you swallow, breathe in mist from, or have skin contact with water that contains germs. The most common RWI by far is diarrhea, usually caused by germs like Cryptosporidium (“Crypto”), Giardia, Shigella, E. coli, or norovirus.
RWIs also include swimmer’s ear, skin rashes (like hot-tub folliculitis), and irritation of the eyes and airways. According to the CDC, RWIs are a real and largely preventable summer health issue — and the prevention is mostly about a few simple habits, not luck.
Why one accident can close a pool for hours
Parents are often surprised that a single “code brown” fecal accident can shut a pool down for the rest of the day. The reason is a germ called Cryptosporidium. Most germs — including E. coli and most bacteria — are killed by properly chlorinated water within minutes. Crypto is different: it has a tough outer shell that lets it survive in a well-maintained pool (1 ppm chlorine) for days.
When a diarrheal accident happens, operators have to follow a CDC-recommended remediation process: clear the pool, raise the chlorine to a much higher level, and hold it there long enough to inactivate Crypto — a process that can take many hours. A formed-stool accident is lower risk and clears faster. The long closure is not bureaucratic caution; it is the only reliable way to handle the one germ chlorine cannot kill quickly.
How chlorine actually works (and its limits)
Chlorine disinfects by chemically breaking down germs, but it needs two things: the right concentration and time. The CDC recommends a free-chlorine level of at least 1 ppm in pools (3 ppm in hot tubs) and a pH of 7.2–7.8, which also keeps the water comfortable for eyes and skin. Under those conditions most germs die within minutes — but “within minutes” is not “instantly,” and Crypto is the stubborn exception.
One myth worth retiring: the strong “chlorine smell” at some pools is not a sign of a clean, heavily chlorinated pool. That smell comes from chloramines — compounds formed when chlorine reacts with sweat, urine, and body oils. A strong smell and irritated eyes usually mean the water needs more fresh chlorine and fewer contaminants, not less. A well-run pool barely smells.
The habits that prevent almost all RWIs
You can prevent the large majority of recreational water illnesses with four habits. First and most important: do not swim — and do not let your child swim — with diarrhea. Wait at least two weeks after diarrhea fully stops if the cause was Crypto. Second: try not to swallow the water. Teach kids that the pool is not for drinking; this single habit prevents most ingestion infections.
Third: take regular bathroom and diaper-change breaks — every 60 minutes is a good rhythm for young children — and change diapers in the bathroom, never at the poolside. Fourth: rinse off in the shower before and after swimming. A one-minute pre-swim rinse removes much of the sweat and dirt that eat up chlorine, and a post-swim rinse helps prevent ear and skin issues.
Swimmer’s ear, rashes, and eye irritation
Not all RWIs come from swallowing water. Swimmer’s ear is an infection of the ear canal caused by water trapped against the skin; dry ears with a towel after swimming, tip the head to drain each side, and see your pediatrician if your child has ear pain. Hot-tub rash is an itchy, bumpy folliculitis from germs that survive in under-disinfected warm water — another reason to rinse off and to be cautious about poorly maintained hot tubs.
Red, irritated eyes after swimming are usually caused by chloramines and pH imbalance, not “too much chlorine.” Well-fitted goggles solve the discomfort for most kids. If irritation is severe or persistent, the pool’s water chemistry is likely off.
Splash pads, lakes, and hot tubs: different risks
Not all recreational water carries the same risk. Splash pads are a surprising hot spot: the water often sprays, drains, and recirculates without the disinfection a pool gets, and toddlers in diapers are the main users — a recipe for spreading diarrheal germs. Treat splash pads as low-disinfection zones and apply the same no-swallowing, frequent-bathroom-break rules.
Lakes and oceans are not chlorinated at all, so avoid swimming after heavy rain (which washes contaminants in) and heed posted advisories. Hot tubs are warm enough that germs survive more easily and chlorine burns off faster; they are the classic source of “hot-tub rash.” Keep young children out of hot tubs for both illness and overheating reasons, and never let anyone swallow the water.
What to do if your child swallows water or feels sick
Swallowing a mouthful of pool water once is rarely a problem — the danger is repeated ingestion of contaminated water. If your child develops watery diarrhea within a few days to two weeks of swimming, keep them out of the water until it fully resolves (and for two extra weeks if a doctor identifies Crypto), push fluids, and call your pediatrician if there is high fever, blood in the stool, or signs of dehydration.
For ear pain after swimming, see your pediatrician — swimmer’s ear is treatable and uncomfortable but not an emergency. For an itchy rash, it usually fades on its own; mention it to your doctor if it spreads or persists. This is general guidance, not a substitute for medical advice for your individual child.
A quick pre-swim checklist for parents
Before you let the kids in, you can do a fast gut check: Does the water look clear, with the bottom of the deep end clearly visible? Is the smell mild rather than overpowering? Are drains and equipment intact? Public pools in many areas post inspection results — ask to see them. None of this requires test strips, though a home test kit is reasonable for backyard pools.
Recreational water illnesses are common but overwhelmingly preventable. Healthy-swimming habits protect your own family and everyone sharing the water. If your child does develop persistent diarrhea, a high fever, or significant ear pain after swimming, contact your pediatrician — this article is general information, not medical advice.
Frequently Asked Questions
Why does a pool have to close after a poop accident?
Because of Cryptosporidium, a diarrhea-causing germ with a tough shell that can survive for days even in properly chlorinated water. Operators must clear the pool, raise chlorine well above normal, and hold it long enough to inactivate the germ, which can take many hours. A formed-stool accident is lower risk and clears faster.
Does chlorine kill germs instantly?
No. At recommended levels (at least 1 ppm free chlorine, pH 7.2-7.8) chlorine kills most germs within minutes, but not instantly, and Cryptosporidium can survive for days. That delay is why not swallowing pool water and staying out when sick still matter even in a clean pool.
Is a strong chlorine smell a sign of a clean pool?
No, it is usually the opposite. The strong smell comes from chloramines, formed when chlorine reacts with sweat, urine, and oils. It signals the water needs more fresh chlorine and fewer contaminants. A well-maintained pool has only a faint odor.
How do I prevent my kids from getting sick at the pool?
Four habits prevent most recreational water illnesses: don't swim with diarrhea, don't swallow the water, take bathroom and diaper-change breaks about every hour, and rinse off before and after swimming. Drying ears afterward helps prevent swimmer's ear.