Impact of Surface to Water Volume Contact Ratio on the Biomass Production Potential of Products in Contact with Drinking Water

The biomass production potential (BPP) test is a semi-static test for assessment of growth promoting properties of construction products in contact with drinking water (CPDW) under defined conditions. The test is performed at the product¿s surface to water volume contact ratio (S/V) of 0.16 cm-1, that is quite different from the practice in buildings and domestic installations. The goal of this study was to evaluate the importance of the S/V ratio for performance of the BPP test and for correct determining the enhancement of microbial growth by CPDW. The BPP of 10 pipe products were compared under the S/V ratios of 0.16 cm-1 and 1.6 cm-1 in two consecutive trials. Our study found out that the BPP test at the originally proposed S/V contact ratio is a reliable approach for assessment of growth promoting properties of CPDW. The data showed that under the S/V ratio of 0.16 cm-1 the test achieves similar results for the BPP of the tested pipe materials as with a more realistic S/V ratio of 1.6 cm-1. However, the S/V ratio showed a significant effect on the planktonic biomass concentration and heterotrophic plate count in the test waters in contact with the tested pipe materials and that stronger effect on the water quality can be important from hygienic point of view. Therefore, the impact of the S/V contact ratio on drinking water quality should be taken into consideration for assessment of the products in contact with drinking water. For acceptance of the CPDW, besides a Pass/Fail Criterion for the BPP, a second criterion for evaluation of materials on their effect of drinking water quality needs to be developed and the planktonic biomass concentration could be useful one for this purpose.JRC.I.5-Physical and chemical exposure

The Advice of the Ad-Hoc Working Group on Sampling and Monitoring to the Standing Committee on Drinking Water Concerning Sampling and Monitoring for the Revision of the Council Directive 98/83/EC

The scope of the Ad-Hoc Working Group on Sampling and Monitoring is to give advice on selection of sampling points, sample protocols and sample frequencies in the framework of the revision of the Council Directive 98/83/EC on the quality of water intended for human consumption (Drinking Water Directive). This group was installed by the Standing Committee on Drinking Water on 8 May 2007.JRC.I.5-Physical and chemical exposure

A study on assessment of biomass production potential of pipe materials in contact with drinking water

The point of compliance in the European Drinking Water Directive is the consumer¿s tap and thus a set of requirements for the quality of materials used in distribution systems is needed. On European level an approval scheme for construction products in contact with drinking water (CPDW) is under development. The Regulators Group proposed in its 12th meeting in 2003 that the Biomass Production Potential (BPP) test should be the basis for assessment of microbial growth support properties of products in contact with drinking water as developed in the CPDW project (2003). The goal of this study is to evaluate the growth promoting properties of selected pipe materials using the BPP test. The pipe materials under study showed different capacity to enhance bacterial growth and their BPP values can be ranked: Cu < SS < PP < PEx < PE < PVCp. The tested materials differed in the contribution of attached biomass (AB) to the total BPP. Materials with a high BPP value and a relatively lower AB/BPP ratio have a higher potential to impair bacteriological water quality. A proportional relation between planktonic bacterial growth in the test water and the BPP of materials under study was observed. We propose that the acceptance of products to be used in contact with drinking water should not solely be made on the evaluation of the BPP value, but should include the evaluation of the PB value.JRC.DDG.I.2-Chemical assessment and testin

Assessment of microbial growth potential of PVC flexible tubing in contact with drinking water

The microbial growth on plasticized polyvinylchloride (PVCp) tubes approved for food contact and used for water supply of coffee vending machines was determined. Four PVCp flexible tubes used for water transfer were tested for their Biomass Production Potential (BPP) using the original tube immersion test and a new ‘tube filling‘ test. Comparison of the microbial growth potential of one PVCp trademark in laboratory tests and during real usage was done. In all tests the microbial growth support properties depended on the trademark of the tested PVCp products. The difference between the biomass production potentials of the PVCp products using the immersion BPP test at surface-to-volume contact ratios of 0.17 cm-1 and 1.7 cm-1 was statistically significant for all trademarks. The ‘tube filling’ test has potential to be used for assessment of growth promoting properties of flexible tubing materials.JRC.I.1-Chemical Assessment and Testin

Harmonized European method for assessment of microbial growth potential of material in contact with drinking water

The point of compliance in the Drinking Water Directive (98/83/¿¿) is the consumer¿s tap and thus requirements for the quality of materials used in distribution systems are set. On European level an approval scheme (EAS) for construction products in contact with drinking water is under development. As a part of the EAS procedure, the Biomass Production Potential (BPP) test has been proposed to be used as method for assessment of microbial growth support properties of products intended to contact with drinking water. The paper presents the results from an evaluation of 10 different materials using BPP test. The capacity of the tested materials to enhance microbial growth can be ranked: Cu < SS/GS < PP/PEx < PE < silicone < EPDM < PVCp. Only one of PE products, EPDM and PVCp had the BPP values above 1000 pg ATP/cm2. The BPP test could give reliable evaluations of the materials from the same type. The coefficients of variation of reproducibility for one and the same material were from 2 to 44%. A positive correlation between the planktonic biomass PB and the BPP was observed. The results demonstrate that products unsuitable for their intended use can deteriorate drinking water quality and focus on importance to be tested and approved for their intended use.JRC.I.2-Chemical assessment and testin

Antimicrobial Resistance of Heterotrophic Bacteria and <i>Enterobacteriaceae</i> Inhabiting an Anthropogenic-Affected River Stretch in Bulgaria

The increasing antimicrobial resistance (AMR) of pathogens is a significant threat to human and animal health, but it is also an environmental challenge for water resources. The present study aimed to quantify heterotrophic bacteria resistant to five groups of antibiotics (ABs) in a selected Yantra River stretch (including its tributary, the Belitsa River); to assess AMR prevalence among Enterobacteriaceae; and to assess the impact of urban effluents or rural runoff on AMR prevalence along the river course at eight sampling points. Culture-dependent methods were used in a population-based study of total AMR and for AB susceptibility testing of Enterobacteriaceae isolates. The data reveal significant differences in AMR dissemination and a lower (up to 10%) proportion of different types of antibiotic-resistant bacteria (ARB) in the Yantra River water compared to the Belitsa River (up to 20%). The incidence of resistant Enterobacteriaceae isolates was in the range of 1% to gentamicin to 36% to ampicillin, including multidrug resistance of 19%, and different AMR patterns of isolates from each river. The prevalence of AMR among aquatic bacteria highlights the need for adequate waste water treatment and for management, monitoring and control of treatment processes to limit anthropogenic pressure through discharge of untreated or incompletely treated waste water and to ensure the ecological well-being of receiving waters

The effect of the surface-to-volume contact ratio on the biomass production potential of the pipe products in contact with drinking water

The biomass production potential (BPP) test is a semi-static test for assessment of the microbial growth promoting properties of construction products in contact with drinking water (CPDW) under strictly defined conditions. In 2003 the test was selected for incorporation into a scheme for acceptance of CPDW in the framework of the implementation of the European Construction Product Directive and Drinking Water Directive. The test is performed at a surface-to-volume contact ratio (S/V) of 0.166 cm-1, that is quite different from the practice in buildings and domestic installations. The goal of the study is to evaluate the importance of S/V ratio for performance of the BPP test and for correct assessment of the growth promoting properties of CPDW. The BPP of 10 pipe products were compared under the S/V ratios of 0.166 cm-1 and 1.6 cm-1. The BPP of most plastic products were higher under the S/V ratio of 1.6 cm-1 in individual trials. However, the differences of average BPP values between both ratios were statistically insignificant. The planktonic biomass concentrations showed 4-14 times stronger effect of the products on water quality at higher S/V ratio and this can be important from hygienic point of view. For acceptance of CPDW, besides a pass/fail criterion for the BPP, the planktonic biomass concentration could be taken as a second criterion for evaluation.JRC.DDG.I.2-Chemical assessment and testin

Microbial Activity in Various Sections of the Domestic Distribution System and the Effect of Stagnation

The microbial activity in various sections of the domestic distribution system is studied and the effect of stagnation time is assessed. The concentration of total ATP in samples taken after 1 minute of flushing the consumers tap are generally in the range of <1-10 ng/1. The concentration of ATP in the first 500 ml sample after overnight stagnation is generally higher than the fully flushed sample whereas the second 500 ml sample in succession is always lower than the first 500ml sample: microbial activity in the domestic distribution system is most prominent present near the tap. 20 successive 50ml samples show microbial activity in certain sections of the domestic distribution system under study in more detail. The stagnation time has an effect on the concentration of ATP, but the trend was dependent on the sampling location. The stagnation time is also studied in a continuous semi-dynamic test facility. Copper, stainless steel and polypropene show decreasing concentraiton of ATP with increasing stagnation. Galvanised steel shows two different stagnation behaviours in July and September. The data allow also the assessment of the performance of the water treatment and/or problems in the mains.JRC.I.5-Physical and chemical exposure

Antimicrobial Resistance of Heterotrophic Bacteria in Drinking Water-Associated Biofilms

Antimicrobial resistance (AMR) is one of the major threats to human health and is becoming an environmental challenge for water resources too. Our study&rsquo;s aim was: to assess the AMR of heterotrophic bacteria in drinking water-associated biofilms against six clinically important antibiotics; to compare the prevalence of antibiotic resistant bacteria (ARB) in drinking water and in the associated biofilms; to estimate biofilm formation ability of selected isolates. Culture-dependent methods were used in the population-based study of the biofilms and in assessment of the single-species biofilm formation ability and the AMR phenotype of the isolated strains. The population proportion of the bacteria resistant to each tested antibiotic significantly differed in the biofilms formed in drinking water from different sampling points. In all biofilms, the abundance of tetracycline- and ampicillin-resistant bacteria was low, and of streptomycin-resistant bacteria was high. An increased proportion of the bacteria resistant to ciprofloxacin, chloramphenicol and streptomycin was detected in the biofilms compared to those found in the drinking water. The prevalence of ARB in the biofilms implies an impact on the drinking water quality and an assessment of the attached and the planktonic bacteria is needed to clarify the prevalence of AMR in the drinking water distribution system

Antimicrobial Resistance of Heterotrophic Bacteria in Drinking Water-Associated Biofilms

Antimicrobial resistance (AMR) is one of the major threats to human health and is becoming an environmental challenge for water resources too. Our study’s aim was: to assess the AMR of heterotrophic bacteria in drinking water-associated biofilms against six clinically important antibiotics; to compare the prevalence of antibiotic resistant bacteria (ARB) in drinking water and in the associated biofilms; to estimate biofilm formation ability of selected isolates. Culture-dependent methods were used in the population-based study of the biofilms and in assessment of the single-species biofilm formation ability and the AMR phenotype of the isolated strains. The population proportion of the bacteria resistant to each tested antibiotic significantly differed in the biofilms formed in drinking water from different sampling points. In all biofilms, the abundance of tetracycline- and ampicillin-resistant bacteria was low, and of streptomycin-resistant bacteria was high. An increased proportion of the bacteria resistant to ciprofloxacin, chloramphenicol and streptomycin was detected in the biofilms compared to those found in the drinking water. The prevalence of ARB in the biofilms implies an impact on the drinking water quality and an assessment of the attached and the planktonic bacteria is needed to clarify the prevalence of AMR in the drinking water distribution system