As clear and refreshing as swimming pool water  looks, particularly on a sweltering hot day , it can harbor bacteria, viruses and para-­ sites that can cause what the Center for Disease Control (CDC)   call recreational water illnesses. Instances of these ailments, which include ear  and eye infections and respiratory , intestinal and skin diseases , are dramatically on the rise according to the CDC; reported cases have more than tripled in the past 20 years.

Even if the community you  manage has one swimming pool or several, indoors or out, salt water or fresh, Olympic size or a wading pool-even hot  tubs-it's important  that the water in which residents swim and relax won't make them sick. And community managers and pool mainte nance staff, as well as  municipal and local governments, can do a lot to minimize outbreaks of infections.

Whether a community's pools are maintained and staffed by the association or a contractor, managers should work closely with pool personnel to make sure   every  one who uses the pool observes certain procedures.

It's essential that dressing rooms, bathrooms, showers and pool decks are cleaned and disinfected regularly. Pool users should be educated about why hygiene is a critical element in maintaining healthy pool water and why diapered children should be changed well away from the pool and the surrounding decks.  All swimmers should be encouraged to take    frequent bathroom breaks and   reminded not to swallow pool water.  And urge swimmers to shower with soap each time they enter or leave the pool. Anyone – residents, guests, children, adults and employees – who has an infection or illness should be refused entry to the swimming or wading pool area. Also develop a disinfecting policy for responding to contamination.

It's important to check water pH and chlorine levels regularly, particularly during the weekend or other busy times.   Also, managers and pool staff should be aware that while chlorine is an effective disinfectant, it doesn't kill germs immediately, and some viral and bacterial strains resist chlorine altogether.  F or instance, E. coli bacteria can be eliminated in less than a minute by normal disinfectants, but Giardia, which is a parasite, requires nearly an hour. The virus that  causes Hepatitis A survives in chlorine for only about 15 minutes, but the parasite Cryptosporidium can live in chlorinated water for more than a week before it's destroyed. Any of these  organisms can cause mild to severe  fatigue, stomach cramps, vomit ing and diarrhea. Strep and other bacteria that cause colds and car infections also can spread freely in swimming pools. 

The chemicals used to sanitize pool water are themselves toxic if used, stored or applied improperly, so make sure they are always handled by properly trained personnel. The association also should keep records of pool maintenance, disinfectant use and pH measurements.

The CDC released the Model Aquatic Health Code (MAHC) in September 2014 as guidance for local governments, pool programs and others who have vested interest in "improving the health and safety at public aquatic facilities." This code is available on the CDC's website at www.cdc.gov/healthywater/swimming/pools/mahc/about.html. 

A complete checklist of critical steps to take to ensure pool water safety is available at www.cdc.gov/healthywater/swimming/resources/operating-public-swimming-pools-factshcet.html. 

Swimming pools are a great source of recreation,  exercise  and  relaxation-and managers should do everything possible  to ensure they won't make swimmers sick.