Comprehensive water quality testing of high-use public spas.

Introduction

Recent media reports have focused on potential adverse health effects of local health clubs and spas (1). The Cuyahoga County Board of Health (CCBH) responded to these reports with a comprehensive review of sanitary and environmental conditions of these facilities including locker rooms, pools, and equipment. Spas were placed under the greatest scrutiny because of their potential adverse effects on public health and safety. Although public bathing places are currently inspected and are not considered to be a major public health problem, the study focused on the water quality of spas because of: 1) the potential for transmission of intestinal diseases and infections of the skin and mucous membranes, 2) large bather loads in heavy-use periods, and 3) the existence of measurable health-code standards.

Studies conducted by the German Federal Health Office and the Oregon State Health Department suggest that the parts per million (ppm) of disinfectant alone is not an accurate measure of bacteriological water quality unless other factors such as pH, total dissolved solids (TDS), and cyanuric acid are all maintained at acceptable levels (2). As a more reliable alternative, a direct measurement of the oxidation-reduction potential (ORP) has been proposed by the Ohio Department of Health to monitor the water quality of spas and will be required statewide by January 1, 1996. In light of these developments, CCBH initiated a study to combine the standard water chemistry testing with bacteriological sampling to determine the efficacy of disinfection treatment, the confidence in standard chemical testing, and ultimately, a more accurate profile of the quality of spa water.

Materials and Methods

The preliminary study was designed within the framework of health code regulations and based on the protocol from Standard Methods for the Examination of Water & Wastewater. The bacteriological standard from Public Swimming Pool, Spa, and Special Use Pool Rules is, "Not more than two hundred bacteria per [TABULAR DATA FOR TABLE 1 OMITTED] milliliter as determined by the standard (thirty-five degrees Celsius) agar plate count. A pool or spa shall be in violation of the standards if more than fifteen percent of at least four samples taken within thirty days exceed one of the standards" (3). Because coliform bacteria are insufficient to judge the microbiological quality of whirlpool water, the heterotrophic plate count, formerly known as the standard plate count, is the primary indicator of disinfection efficiency for indoor pools. The membrane filter method, in particular, permits the testing of low turbidity water and is the method of choice for low-count waters (4).

While this study was designed to meet the above guidelines, it was limited in scope by: 1) laboratory capacity, 2) incubation time, and 3) collection and processing time. The available space allowed 48 plates to be incubated for a period of 48 hours. Since each sample yields three plates, only sixteen spas could be sampled in any 48-hour interval. Furthermore, the time required for collection and processing necessitated the use of two sanitarians (each collecting a maximum of eight samples per 48 hours) so that all samples were delivered to the lab and processed within eight hours. One final restriction, the 48-hour incubation period, precluded sampling on Thursdays and Fridays. The finalized schedule allowed for the collection within a thirty-day period of five samples each from a total of seventeen spas at eight east side and nine west side locations. Spas in the health/racquet/exercise club category were selected due to their heavy use and potential for producing a worst-case scenario relative to other spas. The sampling at these establishments was unannounced and occurred at different days and times throughout the study period.

The sampling protocol was adhered to closely in order to minimize any variation in technique or procedure between the two project sanitarians. During the initial visit to each establishment, the program manager of the pool program accompanied the project sanitarians to survey the pump room and spa facilities, explain the purpose of the study to the operators, and evaluate the technique of the sampling procedure. The established procedure required the sampling sanitarian to:

1) Note the number of bathers and ask them to exit the spa.

2) Turn off the jets and allow the water to remain calm for five minutes prior to obtaining a sample for bacteriological analysis.

3) Conduct water chemistry tests, (temperature, free and total chlorine, pH, TDS, and cyanuric acid), with a Taylor K-2005 test kit.

4) Apply an alcohol preparation to both hands before putting on one disposable latex glove.

5) Collect 100 mL of spa water into a sterile Whirl-Pak Thio-Bag. [The bag, which contains sodium thiosulfate to neutralize the disinfectant, is held inverted by the gloved hand into the water one foot deep and one foot out away from skimmers or return lines.]

6) Store the sample on ice and transport it to the lab within six hours.

7) Process samples within two hours using the HPC Membrane Filter Method at dilutions of 10, 20 and 40 mL with m-HPC media at 48-hour incubations (5).

Plated samples were placed in a Thermolyne culture incubator with a dish of distilled water to maintain the humidity within the unit. Upon completion of the incubation, the colony-forming units (CFU) were counted with the aid of a stereoscopic microscope at a 10x to 15x magnification and a light source which was placed at a 45-degree angle to the plates. The procedure for calculating CFU is based on the number of colony-forming units per square as follows:

1 to 2 or fewer CFU per square

Count all colonies on the plate & multiply by the reciprocal of the dilution.

3 to 10 CFU per square

Count ten squares, obtain an average count per square, and multiply by 185 times the reciprocal of the dilution.

10 to 20 CFU per square

Count five squares and multiply the average count by 185 times the reciprocal of the dilution.

TABLE 2

Spa Data Averages.

Site   Average Free   Average pH   Average TDS   Average CFU/mL
       Disinfectant

1           5.5           7.5          280          (*) 121
2           4.0           7.3         1640                1
3           5.0           7.6          925                1
4           4.2           7.3          800                1
5           3.5           7.6          520                3
6           4.0           7.6          300                9
7           3.5           7.8          340           (*) 66
8           4.6           7.4         2700                2
9           2.8           7.8          475                1
10          1.8           7.8          800                1
11          3.0           7.6          400                1
12          3.9           7.2          620                1
13          2.5           7.5          525               10
14          2.3           7.2         1500                1
15          2.4           7.1         3120                1
16          4.0           7.4         1460               16
17          3.4           7.8         950                 1

* Calculated from data containing estimated values reported as
"[greater than] 200 CFU/mL"

[greater than] 20 CFU per square

Record count as [greater than]2,000 times the reciprocal of the dilution. All averaged counts are reported as estimated CFU.

Results

The seventeen spas involved with this study may be further divided into three classes: (A) franchised health club, (B) racquet club, and (C) fitness center. Class A consists of eight establishments representing two different franchises. Class B is composed of three establishments with clientele whose primary activity is tennis, racquetball, or squash. Class C is represented by five establishments (one with separate men's & women's spas) with general fitness equipment and activities.

A total of 81 samples were collected from 17 spas at 16 establishments (four scheduled samples could not be collected because the spas in question were closed for repair). Four of the spas were equipped with automatic controllers which read disinfectant levels and adjust the amount of disinfectant fed to the spa water accordingly. Disinfectants used at these spas include sodium hypochlorite (11 spas), bromine (5 spas), and stabilized chlorine (1 spa). The Ohio state health regulations require spa water to have a free disinfectant residual of at least two parts per million (ppm), a pH between 7.2 and 7.8, a cyanuric acid concentration less than 100 ppm, a total dissolved solids concentration less than 3000 ppm, and a heterotrophic plate count less than 200 CFU/ mL. The corresponding water chemistry tests identified: free chlorine/bromine violations in 17.3% of the samples (14/81), pH violations in 14.8% of the samples (12/81), cyanuric acid violations in 0% of samples (0/4) from spas using stabilized chlorine, TDS violations in 6.2% of the samples (5/81), and 4.9% (4/81) of the samples exceeding the bacteriological standards. Table 1 contains a summary of this data. The letters A, B, and C refer to the three classes: franchised health club, racquet club, and fitness center, respectively. The fifth column shows the percentage of samples from each spa which exceeds the bacteriological standard while columns six through nine do the same for the chemical parameters (disinfectant, pH, TDS, and cyanuric acid).

Graph 1, "Free Disinfectant vs. CFU," shows the average free chlorine/bromine ppm for each spa in relation to the average number of colony-forming units of heterotrophic bacteria at the same site. The minimum allowable concentration of chlorine or bromine is 2.0 ppm.

Graph 2, "pH vs. CFU," shows the average pH value for each spa compared to the average number of colony-forming units of heterotrophic bacteria at the same site. The acceptable range for pH is 7.2 to 7.8.

Graph 3, "TDS vs. CFU," shows the average total dissolved solids in ppm relative to the average number of colony-forming units of heterotrophic bacteria. The TDS units depicted on the bar graph must be multiplied by 100 to calculate the actual values for total dissolved solids. Refer to Table 2 for data used to plot the graphs.

Discussion

The HPC is an extremely sensitive test which is much better suited than the coliform test for judging the efficiency of water disinfection for several reasons. Because coliform bacteria are naturally abundant in the intestines of warm-blooded animals, this group of bacteria is an excellent indicator of sewage pollution. In the spa environment, however, feces is only one type of human waste product which may be present in the water. The heterotrophic bacteria are ubiquitous and, because they are found on the skin of humans, may easily be introduced into spa water. This fact highlights the need for extra precautions to prevent contamination during the sampling and processing procedures.

Under ideal conditions, the bacteriological samples should be taken during peak use periods. Based on the observations of local spa operators, the busiest season is during the colder months when people tend to exercise indoors, with the peak time being late afternoon or evening. Most of these samples were taken before 2:00 p.m. during the months of May and early June. Even though the sampling events were unannounced, it is important to consider to what degree the spa operators' anticipation of additional sampling may have biased this study.

This study was designed to test the premise that, given an adequate concentration of disinfectant in chemically balanced water (proper pH, TDS, and cyanuric acid), analysis for heterotrophic bacteria should yield very low counts - well below the health code standard. This in fact is known to be true if the majority of free chlorine is in the form of hypochlorous acid, the component with a faster bacterial kill time (6). Since chemical test kits cannot isolate and measure the concentration of this one component of free chlorine, it is necessary to monitor other factors such as pH, TDS, and cyanuric acid which when not within ideal parameters can decrease the percentage of hypochlorous acid. In order to maximize the percentage of hypochlorous acid, the pH must be 7.4 to 7.6, the TDS below 2000 ppm, and cyanuric acid concentration below 100 ppm. The pH level has added significance because free chlorine is most effective as a disinfectant at levels lower than the limit established in the health code [ILLUSTRATION FOR FIGURE 1 OMITTED] (7). This lower limit protects bathers from eye irritation associated with pH levels below 7.2. The results of this study indicate that 92.5% of the samples with water chemistry parameters within the above range were in compliance with the bacteriological standard. It is interesting to note that all four samples with the number of CFU exceeding the bacteriological standard come from spas which use bromine as a disinfectant. Unlike chlorine, bromine is more effective as a disinfectant when the pH is greater than 7.8, the upper limit set forth in the Ohio health code. Furthermore, levels of bromine twice the amount of chlorine have been recommended to ensure adequate disinfection (8). Based on this information, those samples (having at least 200 CFU/mL) with a pH higher than 7.8 and bromine concentrations greater than 4.0 ppm may be false high counts resulting from either sampling or analytical error. The inadvertent capture of floating debris, for example, is an example of an error which might occur while collecting a water sample.

Recommendations

Operators of spas are responsible for maintaining equipment and facilities, monitoring bathers, and supervising employees so that they provide a safe and healthy environment at all times. Recommendations which will facilitate the maintenance of good water quality require the operator to:

1) operate only approved filtration equipment of adequate design and capacity.

2) maintain proper levels of disinfectant, pH, TDS, and cyanuric acid through frequent testing and required documentation of the water chemistry testing.

3) properly calibrate automatic controllers at the start of each day of spa operation.

4) monitor the entry of bathers to ensure adequate hygiene.

5) maintain a smooth and easily cleanable interior spa surface to eliminate areas which may harbor, and promote the growth of, bacteria.

6) frequently clean and disinfect floor surfaces leading to the spa area to reduce tracking of foreign objects into the water.

Conclusion

The results of this preliminary study support the use of chemical testing as an effective means for routine monitoring of spa water quality. This method provides reliable and immediate water quality data which facilitates the identification and correction of conditions which may pose a threat to the safety and health of bathers. Additional studies should be conducted during peak season and time of day as well as at spas other than those located at health, racquet, and exercise clubs.

REFERENCES

1. Meyer, Tom (1995), "Germs in the Gym," WJW Channel 8 Fact Finder Series, Cleveland, Oh., February 8, 9, and 10.

2. Steininger, J.M. (1985), "PPM or ORP: Which should be used?" Swimming Pool Age & Spa Merchandiser, Nov., pp. 1-2.

3. Ohio Department of Health (1994), Public Swimming Pool, Spa, & Special Use Pool Rules, Columbus, Oh., p. 44.

4. American Public Health Association, American Water Works Association, Water Pollution Control Federation (1989), Standard Methods for the Examination of Water & Wastewater, (17th ed.), pp. 9-54.

5. American Public Health Association, American Water Works Association, Water Pollution Control Federation (1989), Standard Methods for the Examination of Water & Wastewater, (17th ed.), pp. 9-58.

6. Steininger, J.M. (1985), "PPM or ORP: Which should be used?" Swimming Pool Age & Spa Merchandiser, Nov., pp. 2-3.

7. U.S. Department of Health & Human Services, Public Health Service, Centers for Disease Control (1988), Swimming Pools: Safety & disease control through proper design & operation, Atlanta, Ga., pp. 60-61.

8. Steininger, J.M. (1985), "PPM or ORP: Which should be used?" Swimming Pool Age & Spa Merchandiser, Nov., pp. 5-6.

Corresponding Author: Timothy E. Gallagher, R.S., Cuyahoga County Board of Health, 1375 Euclid Ave., Cleveland, OH 44115-1882.