OK everyone, time to go to the pool. Here's our checklist: towels, water slippers, sunglasses, suntan lotion and prevention of RWIs. Huh, what's an RWI? Well, unfortunately, the term RWI has become more common. It stands for recreational water illness, and some RWIs can be downright dangerous.

Even though millions of people swim safely in public areas each year, it's important to know that certain infectious diseases can occur while swimming in public pools, water parks, lakes, decorative water fountains in the city and yes, even the ocean.

C'mon Doc, It's a Big Pool
To be blunt, public water facilities are like giant bathtubs. You're essentially bathing with everyone in the pool. While this may be a neat way to meet people, it's important to practice good pool hygiene to prevent or decrease the chance of either spreading or getting an infection.

While most potential infections involve the gastrointestinal tract and diarrhea (remember the severe illness related to fecal contamination in a water park in Georgia?), infections of the eyes, ears, respiratory system and skin can also occur.

What About Chlorine?
Chlorine does a "good job of killing most germs," but it doesn't make the water germ-free, says the Centers for Disease Control (CDC). The agency says that "a few germs can survive normal pool, hot tub, and spa levels of chlorine for several hours to days," and that chlorine levels must be properly maintained to kill most germs.

In fact, warm-water temperatures may cause chlorine to evaporate faster, making germ fighting ineffective. Also, there's a good reason behind pool signs that ask you to shower before you enter the pool. (I know you must be thinking: "What difference does it make? I'm going to get wet anyway?") The main reason is because sweat contains nitrogen and ammonia, which can react with chlorine and reduce its effectiveness. In fact, urine, hair spray and suntan oil can all have the same effect. When this occurs, a chlorine smell may develop, indicating that all is not is not well at the pool.

Avoiding the Bacterial Threat
The CDC has released the following recreational swimming tips to decrease the chances of bacterial contamination.

• Try not to swallow the water.

• Do not go into the water if you have diarrhea. You can spread germs in the water even without having an "accident."

• Wash your hands and bottom thoroughly with soap and water after a bowel movement, or changing diapers. (Remember Poppy from Seinfeld who wanted to cook Jerry something special even though he didn't wash his hands after using the toilet? Yuck!) Germs on your hands can end up everywhere, including pool water.

• Notify the lifeguard if you see fecal matter in the water, or if you see people changing diapers on tables or chairs near the pool area.

For Parents

• Take your child to the toilet for frequent bathroom breaks. (Waiting until you hear "I have to go" may be too late.)

• Change diapers in the bathroom, not near the pool or shoreline, because germs can contaminate surfaces around the water.

• Wash your child thoroughly (especially his or her bottom) with soap and water before swimming.

• Don't count on swim diapers or pants to keep fecal matter from leaking into the water. (These products are not leakproof.)

Look Before You Leap
Pool coloration can provide some key clues about water quality. Here are some warning signs that can indicate a water-safety problem:

• Foamy buildup in a pool or spa means the water has organic contaminants — not a good thing!

• A strange color. Pea green can indicate the presence of algae. A slight green or reddish-brown may mean copper, iron or other metals in the water, possibly indicating plumbing or other problems.

• Pink slimy stuff around railings or edges. This may actually be bacteria and indicate the pool chemicals are out of whack.

Lastly, avoid swimming in the ocean for at least 24 hours after a heavy rain because storm-water runoff from the streets and drainage areas may wash pollution into the water. Also avoid swimming near pipes which act as water-runoff outlets from land-based areas. Hanging out in such water holes is like washing yourself with water used to clean your kitchen floor.

Safe Swimming
Here are some swim-safety tips from the American Red Cross:

• Keep your eye on your child at all times when he or she is near water.

• Always swim with a buddy; never alone.

• Don't drink alcohol and swim. Alcohol impairs judgment, balance and coordination.

• To avoid choking, don't chew gum or eat while swimming.

• Stop swimming as soon as you hear or see a storm in the distance. Lightning can travel as far as eight miles from the storm and, as you probably remember from science class, water conducts electricity, so keep out of the pool or water.

• Obey signs that say no diving; these areas have been deemed unsafe for this activity.

• Watch out for the "dangerous too's" — too tired, too cold, too far from safety, too much sun, and too much strenuous activity. If you experience any of these, get out of the water. Keep the fun in summer by practicing water safety.

Copyright 2003, Dr. Rob Danoff

Robert Danoff, D.O., M.S., is a family physician. He is program director of Family Practice Residency Frankford Hospitals, Jefferson Health System, Philadelphia, Pa. He also is a medical correspondent for The Comcast Network, CN8, contributing writer to the New York Times and writes a weekly medical column for the Bucks Courier Times, Bucks County Pa.