Feature Article - July 2009
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Water Hazard

Managing Aquatic Risk

By Daniel Margolis


An Ounce of Prevention

As with many forms of aquatic risk, the best defense against recreational water illness (RWI) is a combination of a well-designed and -maintained facility and well-trained pool operators and staff. But sometimes a little common sense is called for as well.

In 2007, the state of Utah saw an outbreak of cryptosporidium in its public pools, with 1,600 reportedly falling ill. The eventual cause of the outbreak was determined to be toddlers with soiled diapers being allowed in pools, and in late August public health officials asked aquatic facility managers to restrict children under the age of 5 from swimming until the outbreak had subsided.

Aquatic Design Group Principal Randy Mendioroz describes the breakdown that occurred here.

"They were not enforcing common-sense regulations with respect to the public, because we had moms with their little kids literally changing diapers right next to the water or even in the water in a zero-depth entry portion and then washing [them] off on the ground sprays," he said.

This is obviously not sanitary, but once the cause was determined, what followed was an overreaction, Mendioroz believes. "Basically the state of Utah said kids with diapers on them will not be allowed in any public pools, period, so they just way overreacted. A little bit of common sense would tell you not to change a diaper in a swimming pool."

According to Mendioroz, modern pools, if used correctly and in adherence with state codes, can guard effectively against RWIs. Pools use automated control systems that monitor water chemistry either by oxidation-reduction potential or the parts-per-million of chlorine within the water and its pH.

"Most commercial swimming pools have this type of equipment, and they can adjust the feed rate when 300 kids jump in the pool at 1 o'clock in the afternoon," Mendioroz said. "Assuming that the pool is properly designed, it's got an adequate number of turnovers, conforms with the local health codes and you've got an automated water control system, you can nip most of these RWIs in the bud before you have a problem. With a regular program that you're following up on of superchlorination to burn out chloramines, making sure that you have active chlorine residual in your pool water, it's going to take care of 90 to 95 percent of the issues."

But what about the remaining 5 percent? To target that, pool operators can choose to use ultraviolet water sterilization or ozone water purification. "It's a belt-and-suspenders kind of approach where you use a much more powerful oxidant indicates of ozone, like 30 times more powerful than chlorine, while in the case of UV sterilization you basically inactivate the bacteria or virus by passing it through this UV sterilization contact chamber," Mendioroz explained.

These are the most popular methods of combating RWIs in the United States to date. In Europe, more highly evolved methods of water filtration are being introduced.