How to tell if a pool is properly chlorinated

Most swimmers understand that chlorine is added to pools to kill germs that can make swimmers sick.  Chlorine-based pool sanitizers help reduce swimmers’ risk of waterborne illnesses, such as diarrhea, swimmer’s ear, and various skin infections.  The great advantage of chlorine over other sanitizers, such as ozone and UV is that it keeps working long after it is added to pool water; chlorine provides a “residual” level of protection against germs in the water.  Chlorine is not the only “game in town” when it comes to pool sanitizers, but of the common products, only chlorine- and bromine-based disinfectants provide significant residual protection.  Salt-water pools, by the way, are chlorinated pools in which the chlorine is generated on site from sodium chloride.

It’s important to get the pool chemistry right

Pool managers strive to keep the “free chlorine” level of pool water between about one and three parts per million.  Maintaining the chlorine level in that range depends on several factors, including the pH of the water (it should be between 7.2 and 7.8), and the presence of unwanted substances in the pool, such as urine, perspiration, body oils and lotions, which compete with chlorine and react with it.  These substances add to what is known as the “chlorine demand.”

Products of chemical reactions between chlorine and substances added by swimmers are irritants known as chloramines.  It is chloramines, not chlorine, that are responsible for swimmer red eye.  Unshowered and unhygienic swimmers (read:  those who pee in the pool), add to the “chlorine demand” and are often the real cause of swimmer red eye.  Unfortunately, as chlorine reacts with impurities brought into the pool by swimmers, there is less of it available to kill germs.  So, not only do unhygienic swimmers promote irritants forming in swimming pools, they may also inadvertently raise the risk of waterborne illnesses.  More chlorine may be needed to chemically destroy the chloramines formed and restore a free chlorine residual.

Swimmers can help keep swimming healthy

This comes as a surprise to many swimmers.  The fact is that swimmer hygiene affects the chemistry of the pool and the comfort of swimmers.  Last summer we made the point that swimmer “red eye” is an indicator that someone might have peed in the pool.  That raised awareness and quite a few eyebrows.  This year, we join our efforts to those of the Centers for Disease Control and Prevention and ask swimmers to shower before swimming and never pee in the pool.  When you walk out to the pool this summer, sniff the air and decide whether or not you are about to jump into a healthy pool!

Swimming is a great way to cool down from the sweltering heat and squeeze in a cardio and strength training workout, but don't let the sight of bright blue water drown your better judgment. Not all swimming situations are created equal, and some can even land you or your loved ones in the emergency room if you're not careful. So before you slather on the sunscreen and grab your pool float, review this list of red flags. These signs are clear warnings that what might look like a day of summer fun could spell big trouble.

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1 The pool manager doesn't test the water

Pools need a lot of care and attention to detail, and the manager on duty should be vigilant. Monitoring the chemicals is especially crucial to maintaining healthy waters. A pool's chemical levels should be tested at least twice a day.

Pool attendants who forget to test and fail to make appropriate adjustments put swimmers' safety at risk. If the pool's chlorine level isn't being carefully monitored, it may be a petri dish of bad bugs like norovirus, which can cause innocent swimmers bouts of vomiting and cramps.

2 It has cloudy or dirty water

If a pool's water isn't sparkling and clear, don't even think about diving in. Not only does this condition suggests poor maintenance, but lack of visibility itself poses a threat. Be sure to also look out for broken or missing pool drain covers, which are made to reduce entrapment—when the pool's powerful suction from the water circulation system causes someone to become trapped underwater. Check out this video from the ZAC Foundation to learn how a compliant and a non-compliant pool drain looks like.

3 Algae is growing in the water

Blue-green algae produces toxic cyanobacteria and can grow in poorly sanitized pools, particularly in areas that receive a lot of sunlight. The slimy and often smelly film that floats on the water's surface is a distinct green color, so look carefully for it before going for a swim. If there's an off-smell, don't go for a swim and don't let your dog take a plunge either.

4 There are several babies in the same pool

Sure, babies in the pool are cute, but pre-potty-trained babies don't make good swimming pals. Trace amounts of fecal matter can harbor the parasite Giardia lamblia. Diaper leakage—which is hard to prevent, especially in the water—can easily contaminate an entire pool. Accidentally ingest some of the germs, and you're looking at a miserable bout of diarrhea and vomiting you could have avoided by sticking to the adult swim area.

5 There's a large crowd in the pool

The expression "the more the merrier" may apply to many things, but not a public pool. It's a matter of mathematics: Each new body multiplies the germs, viruses, and bacteria getting into the water. More and more swimmers also divide the lifeguard's attention, which equals less safety for all. If the pool seems way too crowded, it probably is. Cool off with some ice cream or a homemade smoothie instead.

6 Pool ladders aren't stored away when they're not in use

Having pool ladders are essential for getting into and out of the water, but if adults or a lifeguard isn't present, they should be put away to prevent young kids from getting access, especially at above-ground pools. Kids can play on them when adults aren't paying attention and accidentally slip into the pool.

7 There aren't safety fences around the pool

Proper fences and barriers should be put in place at all public pools for kids, and those that don't have these safety measures in place are red flags. According to the U.S. Consumer Product Safety Commission, fences of at least four feet high should surround a pool or spa on all sides, and they shouldn't be climbable for young children. People should also avoid propping fences open so kids and toddlers aren't able to easily walk through without adult supervision.

Some pools also have supervisors on watch at pools, in addition to having lifeguards on duty, to help reduce the risk of drowning. Parents of children can also become a "Water Watcher," which means they agree to watch the kids in the water without distractions and carry a Water Watcher card. After a certain period of time, you can pass the Water Watcher card to another adult.

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