Effects of holding time and temperature on conform numbers in drinking water

McDaniels, Audrey E.; Bordner, Robert H.

doi:10.1002/j.1551-8833.1983.tb05195.x

Cited by 13 publications

(10 citation statements)

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“…McDaniels et al (1985) found 14 and 40 % mean reduction in recoveries from 6 to 30 h at 5°C of Enterobacter cloacea and Citrobacter freundii (total coliforms), respectively, seeded into drinking water samples. In an earlier study of naturally occurring total coliforms in drinking water, McDaniels and Bordner (1983) found a small amount of decline (as shown by a graph) between 6 and 30 h at 5°C, but did not present recovery numbers. Bacterial indicators in groundwater have been found to be more stable because of fewer predators, lower temperatures, and less available nutrients than in surface waters, thereby allowing for a longer holding time (McCarthy 1957;Bitton et al 1983).…”

Section: Discussionmentioning

confidence: 86%

“…Other published holding times for fecal-indicator bacteria samples in surface water and groundwater range from 6 to 24 h depending on whether the samples are being analyzed for compliance or noncompliance purposes and whether they are potable or non-potable water (APHA 2005). Many of the published holding time studies are older studies done with drinking water samples (Standridge and Lesar 1977;McDaniels and Bordner 1983) or one more recent study done with surface water samples (Pope et al 2003); none were done using untreated groundwater. These studies found insignificant reductions in fecal-indicator bacteria concentrations in samples with a longer holding time and concluded that results generated within 24-30 h were comparable to those generated within 8 h of sample collection.…”

Section: Introductionmentioning

confidence: 97%

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Holding-time and method comparisons for the analysis of fecal-indicator bacteria in groundwater

Bushon

Brady

Lindsey

2015

Environ Monit Assess

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As part of the US Geological Survey National Water-Quality Assessment Program, groundwater samples from domestic- and public-supply wells were collected and analyzed for fecal-indicator bacteria. A holding time comparison for total coliforms, Escherichia coli, and enterococci was done by analyzing samples within 8 h using presence/absence methods and within 18-30 h using quantitative methods. The data indicate that results obtained within 18-30 h were not significantly different from those obtained within 8 h for total coliforms and enterococci, by Colilert® and Enterolert® methods (IDEXX Laboratories Inc., Westbrook, ME), respectively. Quantitative laboratory methods for samples analyzed within 18-30 h showed a statistically significant higher detection frequency when compared to presence/absence methods done within 8 h for the following methods, E. coli by Colilert and enterococci by membrane filtration on mEI agar. Additionally, a comparison of methods for the enumeration of enterococci was done. Using non-parametric statistical analyses, results from the two methods were statistically different. In this study, the membrane filtration method on mEI agar was more sensitive, resulted in more detections of enterococci, and results were easier to interpret than with the quantitative Enterolert method. The quantitative Enterolert method produced varying levels of fluorescence, which required additional verification steps to eliminate false-positive results. It may be more advantageous to analyze untreated groundwater for enterococci using the membrane filtration method on mEI agar.

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Section: Discussionmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 97%

Holding-time and method comparisons for the analysis of fecal-indicator bacteria in groundwater

Bushon

Brady

Lindsey

2015

Environ Monit Assess

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“…Regulatory agencies are increasingly requiring more emphasis on E. coli testing as part of programs aimed at curtailing waterborne disease. Holding time and temperature can have a significant impact on the density of microbiological indicators at the time of sample analysis (4,5,7). Recommendations for E. coli holding times range from 8 h (2,3,9) to 24 h (8), and holding temperatures below 10°C are generally considered acceptable (2,3,8,9).…”

mentioning

confidence: 99%

Assessment of the Effects of Holding Time and Temperature on Escherichia coli Densities in Surface Water Samples

Pope

Bussen²,

Feige

et al. 2003

Appl Environ Microbiol

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Escherichia coli is a routinely used microbiological indicator of water quality. To determine whether holding time and storage conditions had an effect on E. coli densities in surface water, studies were conducted in three phases, encompassing 24 sites across the United States and four commonly used monitoring methods. During all three phases of the study, E. coli samples were analyzed at time 0 and at 8, 24, 30, and 48 h after sample collection. During phase 1, when 4°C samples were evaluated by Colilert or by placing a membrane onto mFC medium followed by transfer to nutrient agar containing 4-methylumbelliferyl-␤-D-glucuronide (mFC/NA-MUG), three of four sites showed no significant differences throughout the 48-h study. During phase 2, five of seven sites showed no significant difference between time 0 and 24 h by membrane filtration (mFC/NA-MUG). When evaluated by the Colilert method, five of seven sites showed no significant difference in E. coli density between time 0 and 48 h. During phase 3, 8 of 13 sites showed no significant differences in E. coli densities between time 0 and the 48-h holding time, regardless of method. Based on the results of these studies, it appears that if samples are held below 10°C and are not allowed to freeze, most surface water E. coli samples analyzed by commonly used methods beyond 8 h after sample collection can generate E. coli data comparable to those generated within 8 h of sample collection. Notwithstanding this conclusion, E. coli samples collected from surface waters should always be analyzed as soon as possible.Escherichia coli testing is an important tool used by public health experts for the prevention of waterborne disease. The detection of E. coli in a water sample from an environmental source provides direct evidence of fecal contamination. Regulatory agencies are increasingly requiring more emphasis on E. coli testing as part of programs aimed at curtailing waterborne disease. Holding time and temperature can have a significant impact on the density of microbiological indicators at the time of sample analysis (4, 5, 7). Recommendations for E. coli holding times range from 8 h (2, 3, 9) to 24 h (8), and holding temperatures below 10°C are generally considered acceptable (2,3,8,9). It is also recommended that when transport conditions result in delays longer than 6 h, the use of field laboratory facilities located at the site of collection or delayed incubation procedures be considered (2). The Surface Water Treatment Rule requirements of the U.S. Environmental Protection Agency (USEPA) for total coliform and fecal coliform monitoring of surface water used as drinking water sources (3) specify that the time from sample collection to initiation of analysis is not to exceed 8 h; the regulations also encourage (but do not require) drinking water system personnel to hold samples at below 10°C during transit.Unfortunately, data from evaluations of microbiological indicator density that support current holding time recommendations are limited, particularly for E. coli....

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“…Studies of coliforms and aerobic pathogens in environmental and effluent water samples [24,30,34,37] have confirmed that refrigerated storage temporarily preserves the integrity of estimates of these communities over a short storage period. However, the anaerobic nature of the produced water samples and microbial populations considered in this study precludes direct comparison with these studies, and necessitates some important qualifications.…”

Section: Changes In Mpn Estimates Of Microbial Population Sizesmentioning

confidence: 91%

“…Refrigeration at 4°C slows substrate uptake and metabolism by many microorganisms without causing cell death [26], and is a common technique for mitigating distortion of environmental and wastewater samples during short-term storage [24,34,37]; however, the effectiveness of refrigeration for preserving oil fieldproduced water samples has not been documented. To the authors' knowledge, no published studies exist that examine the effects of storage on the anaerobic microbial communities relevant to oil field sampling in general or nitrate amendment studies in particular.…”

Section: Introductionmentioning

confidence: 99%

Storage of oil field-produced waters alters their chemical and microbiological characteristics

Hulecki

Foght

Fedorak

2010

J Ind Microbiol Biotechnol

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Many oil fields are in remote locations, and the time required for shipment of produced water samples for microbiological examination may be lengthy. No studies have reported on how storage of oil field waters can change their characteristics. Produced water samples from three Alberta oil fields were collected in sterile, industry-approved 4-l epoxy-lined steel cans, sealed with minimal headspace and stored under anoxic conditions for 14 days at either 4 degrees C or room temperature (ca. 21 degrees C). Storage resulted in significant changes in water chemistry, microbial number estimates and/or community response to amendment with nitrate. During room-temperature storage, activity and growth of sulfate-reducing bacteria (and, to a lesser extent, fermenters and methanogens) in the samples led to significant changes in sulfide, acetate and propionate concentrations as well as a significant increase in most probable number estimates, particularly of sulfate-reducing bacteria. Sulfide production during room-temperature storage was likely to be responsible for the altered response to nitrate amendment observed in microcosms containing sulfidogenic samples. Refrigerated storage suppressed sulfate reduction and growth of sulfate-reducing bacteria. However, declines in sulfide concentrations were observed in two of the three samples stored at 4 degrees C, suggesting abiotic losses of sulfide. In one of the samples stored at room temperature, nitrate amendment led to ammonification. These results demonstrate that storage of oil field water samples for 14 days, such as might occur because of lengthy transport times or delays before analysis in the laboratory, can affect microbial numbers and activity as well as water sample chemistry.

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Effects of holding time and temperature on conform numbers in drinking water

Cited by 13 publications

References 9 publications

Holding-time and method comparisons for the analysis of fecal-indicator bacteria in groundwater

Holding-time and method comparisons for the analysis of fecal-indicator bacteria in groundwater

Assessment of the Effects of Holding Time and Temperature on Escherichia coli Densities in Surface Water Samples

Storage of oil field-produced waters alters their chemical and microbiological characteristics

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