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Swimming Pool Water Disinfectants

DIS/TSS-12 / Apr. 23, 1979
Swimming Pool Water Disinfectants

Numerous factors influence the concentrations necessary for disinfection of swimming pool water in practical applications: numbers of swimmers in the pool; frequency of use; frequency with which water is changed; general weather conditions; and types and degree of organic contamination of the water by the swimmers themselves (e.g., suntan lotions and oils) and by various debris. Therefore, a two-phased study (presumptive laboratory testing and confirmatory field testing) is required.

  1. Laboratory test requirements.
  2. Presumptive efficacy of swimming pool water disinfectants may be substantiated with data derived from the AOAC Method for Water Disinfectants for Swimming Pools or with slight modifications (e.g., pH) thereof, against both E.coli and S.faecalis.

  3. Performance standard for laboratory test.
  4. The lowest concentration of the test germicide providing results equivalent to those of the sodium hypochlorite control is the lowest concentration of the product that can be considered effective.

  5. Field test requirements.
  6. In addition to the laboratory test requirements referred to above, confirmatory efficacy data shall be derived from in-use tests under an Experimental Use Permit in at least two swimming pools. The tests must be conducted for an entire swimming season (4 to 12 months). Reports must include (but are not limited to) the following information concerning the test pools:

    1. The design of the pool, the recirculation and filter system, and water capacity.

    2. The daily bather load.

    3. The amount and identification of all chemicals added daily to the swimming pool water (including the time, site, and method).

    4. The range of chemical characteristics of the swimming pool water, such as: ph, nitrogenous substances, metals, and hardness.

    5. The physical characteristics of the swimming pool water, including temperature and clarity, determined at least daily.

    6. Meteorological data, including air temperature, rainfall and number of hours of sunlight (determined daily) for outdoor pools.

    7. Water samples for bacteriological analysis should be taken on opposite sides of the pool in the shallow area and as remote as possible from the inlets, preferably at the midpoints between inlets. A minimum of 144 samples should be collected during the test period. Samples should be taken just below the surface of the water and preferably at such times when the number of persons using the pool during the preceding hour has been at least equal to 50% of the maximum bather load of the pool and the number of persons in the pool water at the time the samples are collected is at least equal to 25% of the maximum bather load of the pool. Pertinent chemical characteristics of the pool water at the sampling site should be determined at the time of sampling.

    8. The concentration of the antimicrobial agent in the swimming pool water monitored daily at the same time-intervals that the bacteriological assay samples are obtained.

    9. The method that the product user will employ for monitoring the level (concentration in ppm) of antimicrobial agent contained in the pool water.

  7. Performance standard for field test.
  8. The product, when used as recommended in swimming pool water, should demonstrate that not more than 15% of the samples collected shall fail to meet the following bacterial indices.

    1. The standard plate count at 35o shall not exceed 200 colonies per L0 ml.

    2. The most probable number of coliform bacteria shall be less than 2.2 organisms per 100.0 milliliter. When the membrane filter test is used there shall be no more than 1.0 enterococcal organisms per 50 ml.

    3. The most probable number of entercoccal organisms shall be less than 2.? organisms per 50 ml.

* As defined in Suggested Ordinance and Regulations Covering Public Swimming Pools, APHA Joint Committee on Swimming Pools and Bathing Places.

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