June 2004

As the days grow warmer and the school year winds down, students and their families are gearing up for summertime activities. Whether you plan to go to camp, work at a summer job, travel, enjoy hobbies, participate in sports or just relax with no scheduled activities at all (imagine that?), chances are good you will swim in a pool sometime this summer. Because so much summer fun depends on healthy pools, the June chlorine compound is:

Healthy Pools4Summer Fun.

"No chemical elements in that formula," you say? Not true! You will find chlorine in many "Healthy Pools."

Swimming is one of the most popular of all recreational activities. Oh, the relief of entering a pool of clear, refreshing water on a hot summer day! But is that sparkling water germ-free? You may be surprised to learn that increasingly, pools are not being maintained properly, causing swimmers to get sick. How is this possible in our high-tech age? Doesn't chlorine do the job? The answer is YES--but, as with all chemicals, chlorine disinfectants must be used properly to obtain the desired results. And swimmers can play a part in keeping pools healthy, too.

What is a Healthy Pool?

Proper disinfection of pool water helps prevent swimmers from becoming sick from germs that can live in water. We all carry germs on our bodies and they enter the pool with us. Additionally, bird and other animal wastes occasionally infect pools. And.well, we all know there are "accidents," especially among the diaper-wearing crowd.

Scanning Electron
Micrograph of Pseudomonas

Photo Credit: CDC/Janice

Calcium hypochlorite and chlorinated isocyanurates are common chlorine disinfectants that are used to help keep pools "healthy" for swimmers. Pool operators add these compounds to pool water to kill germs that could cause diarrhea and other types of infections in swimmers. You may have heard of an earache called "swimmer's ear" which is caused by the microscopic bacterium Pseudomonas aeruginosa (see photo at left). This bacterium enters pools on swimmers' bodies or on dirt tracked into the pool area. Showering before swimming helps keep these critters out of the pool.

Maintaining The Right Pool Chemistry

Chlorine in pool water is used up chemically as it kills germs, so it must be replaced continually to fight new "micro-critters" entering the pool. Pool operators have the responsibility of maintaining chlorine levels that are high enough to kill most of the germs in the pool. They also adjust the pH for the best disinfection results. Unfortunately, over the course of a day, the amount of chlorine required to maintain steady levels of protection goes up and down like an elevator in a busy office building! For that reason, pool operators must check chlorine levels frequently and adjust the water chemistry. While this is a challenging task, it's also very important because poor attention to pool chemistry may result in unnecessary health risks to swimmers.

Sick Pool: The Warning Signs

You can use your senses to make scientific observations when you go swimming. Remember the check-list below and practice using your senses each time you approach a pool this summer. Notify the pool manager if you suspect a problem.


Use Your Sense of Sight
Does the pool water look clear and blue? You should be able to see through the water down to the drain or painted stripes on the pool floor. Cloudy pool water may indicate the presence of algae.

Use Your Sense of Touch
The sides of the pool should be smooth, not slimy or sticky. If you feel slime or stickiness, you are probably feeling a build-up of germs.

Use Your Sense of Smell
You should NOT smell a strong chlorine-like odor. If you do, you are actually smelling chloramines, compounds that form when chlorine interacts with fluids like sweat and urine from swimmers. In this case, more, not less, chlorine is needed!

Use Your Sense of Hearing
The sound of pool-cleaning equipment is a good sign. Water should be pumped through filters to remove solid objects. The sound of the pump is a good thing.

Don't Use Your Sense of Taste
Just don't taste the water! If you do get some water in your mouth, don't swallow it. By now, you know why!

Doing Your Part to Keep Pools Healthy

Although pool operators are responsible for maintaining proper chlorine levels, as a swimmer, you too can play a role in keeping pools safe. The U.S. Centers for Disease Control and Prevention (also known as the CDC) offers guidelines for healthy swimming.

  • Shower before swimming (this will remove some, but not all germs).
  • Don't swim when you have diarrhea.
  • Try not to get pool water in your mouth, but if you do, don't swallow the water.
  • Never use the pool as a bathroom. If you have to go, leave the pool and use the real bathroom. And wash your hands afterwards.

Now that you are pool-wise--and "sense-able,"
your assignment is to


For more information on healthy pools, visit www.healthypools.org.

For a list of previous "Chlorine Compound of the Month" features, click here.


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