For those of us focused on water quality and public health, the proper operation and health management of our nation's many water parks is a challenging issue. Americans appear to be flocking to these interactive theme parks more and more, and yet it is probable that health safety regimes have yet to be widely developed and enforced. The result could be increases in waterborne pathogen exposure and the development of disease symptoms in a cross-section of the population, primarily young children.

According to the CDC, occurrences of diarrheal recreational water illnesses have steadily increased since the mid-1980s. Whether acquired from water parks, swimming pools, spas, lakes or rivers illnesses caused by Cryptosporidium, Giardia, Shigella, and E. coli affect the health of thousands of Americans each year, particularly young children and those with compromised immune systems.

The following research study submitted by Tracynda Davis, M.P.H. of the Wisconsin Department of Health and Family Services serves to remind that awareness and good maintenance practices are fundamental to the public health, particularly in dealing with public waters. State agencies and facility managers should be relied upon to provide the healthiest environment possible. However, in the end, we, the public, have an equal role in maintaining the public health. Staying aware of the root causes of disease spread, practicing fundamental personal hygiene regimens when we go to public facilities and reporting situations we believe are harmful to the overall public health are the keys to maintaining a safe and health environment for us all.

Joan B. Rose
Homer Nowlin Chair in Water Research
Michigan State University

Chair, Water Quality & Health Council

Water parks are a rapidly growing element of the United States tourism industry. In an effort to attract customers, particularly families, water parks offer creative theme designs from water slides to interactive water activities. However, as the designs for the attractions become more creative, the possibilities for injury and/or infections to the users are multiplied.

The public health responsibility for regulating the operation and design of water park facilities involves both injury prevention/reduction and control of the spread of waterborne disease. To this end, park designers are challenged to reduce abrasion and impact injuries by cushioning surfaces at pool basins and edges with various pad materials. Often, the padded surfaces are designed within a themed décor to enhance the attractiveness of the park. But these same features that protect against injuries may actually increase the risk of waterborne disease by harboring and distributing bacteria. For example, foam padding in high traffic areas may provide interstitial spaces for opportunistic bacteria to escape pool water disinfectants, and potentially infect swimmers.

The Wisconsin Department of Health has completed a 2-year study of five indoor and five outdoor water parks throughout the state. The study was initiated as a general survey of the sanitary conditions at these parks to gain information that would potentially guide in updating existing regulations to encompass theming and advanced designs found in modern water parks. This approach was to essentially provide data for regulators to make better-informed judgments for the health and safety of pool patrons and their children.

A comprehensive surveillance of water, materials and surfaces were sampled and tested quantitatively for of total coliforms, E. coli, E. coli 0157:H7, enterococci, staphylococci, heterotrophic bacteria, and Pseudomonas aeruginosa. All samples were analyzed at the Wisconsin State Laboratory of Hygiene and taken during unannounced visits.

Pool water samples were further sub-categorized into three types commonly found in modern water parks -- Activity pools, Plunge pools, and Wading pools (further separated into wading pools with or without permanent poured in place padded surface). Activity pools are greater than two feet in depth designed primarily for play activity that uses constructed features and devices. Plunge pools are those at the terminal end of waterslides, which carry over 100 gpm of water down a flume. Wading pools, designed for toddlers and small children, do not exceed two feet in depth and may have padded, permanent poured in place impact-attenuating surfaces either partially or completely submerged in water.

Pool waters were tested for compliance per state regulations for water quality. Findings were that 90% of the pool water samples were bacteriologically compliant and 88% were compliant with free chlorine residuals for pools as stated in Wisconsin Administrative Code (1ppm for activity and plunge pools, 2ppm for wading pools)¹. Wading and plunge pools were below the required free chlorine concentration in 12% of the samples, while no activity pool samples were chlorine deficient. Most water parks have automated technology and highly trained staff, which the authors concluded could explain the high compliance compared to other pool studies published focusing on standard pools. Large water parks have more than one person overseeing a multitude of pools. In this survey, all employed 2 or more nationally certified pool operators.

Theming and pad materials

Theming and pad materials used to cushion the impact of a pool slide or other activities were tested; both those submerged in chlorinated water, and those considered damp. Bacteria isolated from submerged features (i.e. landing pads below surface) probably survive because porous interiors and/or surface films offer protection from chlorinated water. The samples located furthest away from pool water, damp samples, contained the highest populations of bacteria. Bacteria found on damp surfaces are also commonly found on people's skin, hair, and nasal cavities and naturally found in the environment. Over 30% of the population are carriers of the bacteria which we found in the materials.²

Play features

Play features were also tested and those designed for young children and babies were found to harbor the most bacteria. Probably due to the incontinent nature of user of these play features, fecal indicators were found frequently (E. coli 13%, total coliforms 53%, enterococci 87%). Skin indicators such as staphylococci were found in up to 80% of the samples. E coli and enterococci were found in concentrations as high as 1050 cfu/100cm² and 24,192 cfu/100cm2, respectively. (Figure 1) E coli 0157:H7, the bacterial strain that caused an outbreak in a water park in Atlanta, was never detected in pool water or in any location in the parks.

Although water samples from pools which contain landing pad materials were shown to contain very low numbers of target organisms, further evaluation was done to determine whether landing on a pad material may discharge target organisms when under the weight of a bather. To mimic this effect, a sterile 25 kg container was pushed against submerged padding material while pool water was simultaneously collected. The pool water prior to mat compression was relatively free of target bacteria, wherein only heterotrophic organisms were found at levels of 257 CFU/ 100mls. However, water collected during mat compression contained heterotrophs (9,260 CFU/100mls) as well as S. aureus and S. epidermidis (228 CFU/100mls and 100 CFU/100mls, respectively). This suggests using landing pads on the bottom of a pool or waterslide potentially release more bacteria into the pool recirculation system. The mats could offer protection from residual chlorine to these organisms, but it is not know how long they could survive after release.

The benefits of preventing impact injuries by the use of pad materials are easily appreciated and permanent rubber surface attenuating materials poured directly onto the pool basin were evaluated as well. During the duration of our study, materials were found to degrade in chlorine residuals of 3ppm, and pieces of the material tested positive for all the target bacteria. The water from wading pools with permanent surfacing materials are ten times more likely to contain P.aeruginosa than those without surfacing materials, and three times more likely to detect S. aureus. (Figure 2)

Figure 2. Frequency of Bacteria Detected

Few of the materials and play features tested provided adequate cleaning procedures, leaving the pool operator to determine by sight what is considered "dirty". Features and materials used in water recreation need maintenance manuals with a cleaning regiment. Proper cleaning procedures must be provided and followed to keep microbes from flourishing in environments lacking a steady stream of chlorine.

Overall, the parks were found to be operating properly. Readers should be cautious not to over emphasis the presence of these organisms. A study done by Ojima et al suggests bathrooms and kitchens harbor some of the same microorganisms, and in similar abundance.³

Pools using pad materials were found to increase the frequency of bacteria detected compared to the pools without pad materials. We recommend that if pad materials and play features are used, they should be considered in inspection criteria. Though pad materials and play features were found to harbor bacteria, a link between the materials and illness has not been established. Pool water is an efficient vehicle for transporting residual chlorine to bacteria and the low incidence of positive samples reflects this.

In an effort to reduce the amount of fecal bacteria transmitted, Wisconsin passed legislation in 2005 requiring diaper-changing stations in all new pools and water parks. This includes both sex restrooms, providing an alternative for baby and small toddler needs in proper locations.

The department recommends simple steps to prevent disease transmission:

• Shower with soap before using pools.
• Urge parents not to bring their child to a water park or any pool if the child has diarrhea
• Don't change diapers on pools decks (fecal material can run off into the pool from the deck if parents are not careful).

Results of this study will be submitted to Environmental Health Perspectives this spring.

¹ Wisconsin Administrative Code. Chapter HFS 172. Safety, maintenance and operation of public swimming pools. Register May 2002, No. 557.

² Arch G. Mainous, III, PhD, William J. Hueston, MD, Charles J. Everett, PhD and Vanessa A. Diaz, MD, MS. 2006. Nasal Carriage of Staphylococcus aureus and Methicillin-Resistant S aureus in the United States, 2001-2002 Annals of Family Medicine 4:132-137

³ Ojima M, Toshima Y, Koya E, Ara K, Kawai S, Ueda N. 2002. Bacterial contamination of Japanese households and related concern about sanitation. Int. J. Environ. Health Res., (12) 41-52.

Water Quality & Health articles are published periodically by the Water Quality & Health Council, an independent, multidisciplinary group that promotes science based practices and policies to enhance water quality and health by advising industry, health professionals, policy makers and the public.