Microbiological contamination from nonpoint sources of pollution is usually related to animal faecal wastes through urban, pastureland and forest run-off of stormwater. Currently-used bacterial water quality indicators cannot discriminate between human and animal faecal contamination and, therefore, it is common practice to treat the risk associated with exposure to water polluted by animal or human wastes as equally hazardous. The purpose of this study was to determine if there is a risk of gastrointestinal illness after a swimming exposure to water contaminated with animal faecal wastes. The health status and swimming activity of volunteer study participants was followed for 49 days during June, July and August. Multiple bacterial indicators of water quality were monitored daily during the course of the study. Swimming-associated symptomatic gastrointestinal illness was observed in individuals who swam in animal nonpoint source contaminated water. Swimmer illness was not associated with high densities of common faecal indicator bacteria or high volume rainy days. Swimmer illness was associated with high numbers of swimmers per day and high densities of staphylococci. The observed illnesses appeared to be caused by a swimmer to swimmer transmission via the water.

Five healthy young women swam in untreated water of known bacterial quality under a variety of hygienic conditions. Evidence based on bacteriological examination of water samples leads to the following conclusions:1. There is a marked variation in the number and types of bacteria shed by a bather while swimming and the variations do not seem to be correlated to the differences in personal hygiene or the menstrual period.2. Faecal organisms may be discharged in considerable numbers by a swimmer after a thorough and careful shower with soap and warm water and yet not be discharged in appreciable numbers by a bather who does not take a shower before swimming.3. Faecal organisms constitute only a small minority of the total number of viable bacteria that are discharged in swimming pool water by a bather during the act of swimming and as such seem to have limited use as indicators of total bacterial pollution.4. Members of the genus Staphylococcus are shed in large numbers under all conditions and Staph. aureus is consistently present. Therefore, this genus appears to be a good choice as an index for the determination of body contamination.5. Further studies are indicated under more stringently controlled hygienic conditions to determine the value of hexachlorophene in reducing microbial flora that a given individual may shed during swimming.

In an effort to determine if bacterial water quality was related to the incidence of otitis externa (swimmer's ear), a retrospective study was conducted from July, 1980 to September, 1980. Data from 29 cases and 29 controls matched for age and sex were collected. Warm air, warm water, age of less than 18 yr, swimming, and length of time spent swimming were associated positively with cases of otitis externa. Water quality, as measured by fecal coliforms, enterococci, and Pseudomonas aeruginosa was not found to be associated with otitis externa.

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aStandards of swimming pool operation have been developed to prevent the spread of communicable diseases and to insure the safety and well-being of persons frequenting swimming pools. Of principal importance are the standards related to the bacterial quality of the water and the procedures for purification. Because of its simplicity of application, its economy of use, and its continuing, bactericidal action through the maintenance of residual levels, chlorine has been and is being used extensively to control the quality of swimming pool water High-free chlorine residuals in swimming pool water have proved so satisfactory in maintaining the sanitary quality of the water that less emphasis will need to be placed on bacterial standards if accurate titrations of the residuals are routinely carried out, say the reporters of this research.