Swimming Pool Water Disinfectants
DIS/TSS-12 / Apr. 23, 1979
EFFICACY DATA REQUIREMENTS
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. 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.
(2) Performance standard for laboratory test. 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.
(3) Field test requirements. 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:
(i) The design of the pool, the recirculation and filter system, and
water capacity.
(ii) The daily bather load.
(iii) The amount and identification of all chemicals added daily to
the swimming pool water (including the time, site, and method).
(iv) The range of chemical characteristics of the swimming pool water,
such as: ph, nitrogenous substances, metals, and hardness.
(v) The physical characteristics of the swimming pool water, including
temperature and clarity, determined at least daily.
(vi) Meteorological data, including air temperature, rainfall and number
of hours of sunlight (determined daily) for outdoor pools.
(vii) 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.
(viii) 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.
(ix) The method that the product user will employ for monitoring the
level (concentration in ppm) of antimicrobial agent contained in the
pool water.
(4) Performance standard for field test.
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.
(i) The standard plate count at 35o shall not exceed 200
colonies per L0 ml.
(ii) 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.
(iii) 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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