Iron Bacteria in Drinking-Water Distribution Systems: Elemental Analysis of Gallionella Stalks, Using X-Ray Energy-Dispersive Microanalysis

“Iron” bacteria belonging to the genus Gallionella were observed by scanning electron microscopy in water samples and attached to pipe surfaces in a Southern California drinking-water distribution system. The cells were recognized by their characteristic elongated helical stalks composed of numerous intertwined microfibrils. Many of the stalks were partially coated with insoluble ferric salt deposits. Stalks recovered directly from water samples were analyzed for their elemental composition by using X-ray energy-dispersive microanalysis. Silicon, aluminum, calcium, and iron were the predominant elements present in the stalks. Smaller quantities of the elements phosphorous, sulfur, chlorine, copper, and zinc were also detected. Manganese, though present in measurable quantities in the water supply, was not detected in the stalks, suggesting that this organism is unable to utilize this element as an electron donor. This represents the first such analysis of Gallionella stalks recovered from environmental samples without prior subculturing in artificial laboratory media.     

The Chemical Composition of Four Regions on a Summer Day in Lake Lacawac,Pennsylvania

This paper is devoted to the varying concentrations of 49 elements found in the water from three littoral sites and one pelagic site, sampled over a five hour period, in Lake Lacawac. These elements were detected in concentrated water samples by use of X-ray emission and optical emission spectroscopy. The elemental concentrations of the four sampling sites differed. Statistical analyses were used to estimate how chemical mixing proceeded in the surface waters of the lake. Results from a previous study of the chydorid Cladocera living in the sediments beneath the water sampling sites indicated that the more organic sediments contained more individuals than the sandy sediments. The chemical concentration of the water followed the same distribution as did the organisms.     

Influence of substratum hydration and adsorbed macromolecules on bacterial attachment to surfaces.

The attachment of Pseudomonas fluorescens and an Acinetobacter sp. to hydrogel and polystyrene surfaces was investigated to evaluate the influence of adsorbed water and macromolecules on adhesion. With both organisms, there was a decrease in attachment numbers with increasing water content of the hydrogels. There was also a decrease in attachment with a decrease in water contact angle on untreated, tissue culture and sulfonated polystyrene surfaces; however, the attachment numbers were higher than would be expected on the basis of the hydrogel data. With P. fluorescens, attachment to untreated and tissue culture polystyrene was inhibited by bovine serum albumin, Escherichia coli lipopolysaccharide, and the supernatant from spent medium, both when the conditioning substances were added to the suspension of attaching cells and when they were preadsorbed onto the surfaces. Dextran inhibited attachment only when added to the bacterial suspension. Supernatants from centrifuged natural freshwater samples had no effect. Thus, hydration of a surface and the adsorption of macromolecules can reduce bacterial attachment; however, additional factors relating to the chemical composition of the substratum and polymeric stabilization of suspended cells can affect the adhesion interaction and resultant numbers of attached cells.     

Influence of substratum hydration and adsorbed macromolecules on bacterial attachment to surfaces

The attachment of Pseudomonas fluorescens and an Acinetobacter sp. to hydrogel and polystyrene surfaces was investigated to evaluate the influence of adsorbed water and macromolecules on adhesion. With both organisms, there was a decrease in attachment numbers with increasing water content of the hydrogels. There was also a decrease in attachment with a decrease in water contact angle on untreated, tissue culture and sulfonated polystyrene surfaces; however, the attachment numbers were higher than would be expected on the basis of the hydrogel data. With P. fluorescens, attachment to untreated and tissue culture polystyrene was inhibited by bovine serum albumin, Escherichia coli lipopolysaccharide, and the supernatant from spent medium, both when the conditioning substances were added to the suspension of attaching cells and when they were preadsorbed onto the surfaces. Dextran inhibited attachment only when added to the bacterial suspension. Supernatants from centrifuged natural freshwater samples had no effect. Thus, hydration of a surface and the adsorption of macromolecules can reduce bacterial attachment; however, additional factors relating to the chemical composition of the substratum and polymeric stabilization of suspended cells can affect the adhesion interaction and resultant numbers of attached cells.     

Survival and detection of rotaviruses on environmental surfaces in day care centers.

Previously, we demonstrated that children in day care centers commonly experience diarrhea due to rotavirus, giardia, and bacterial pathogens. Multiple agents frequently coexist, and the environment is heavily contaminated with enteric bacteria during outbreaks. A study of environmental surface contamination with rotavirus was performed during three non-outbreak periods. Of 25 samples collected from environmental surfaces and teachers hands at a day care center, 4 (16%) were positive for rotavirus antigen when a fluorescence assay was used. We also examined the survival of two animal viruses, rotavirus SA-11 and poliovirus type 1, and bacteriophage 12 on similar environmental surfaces in a laboratory. Poliovirus type 1 and bacteriophage f2 were more resistant to drying than rotavirus SA-11 and could be recovered after a 90-min exposure on a dry surface. Rotavirus SA-11 could be detected for 30 min. All three viruses survived longer when they were suspended in fecal material than when they were suspended in distilled water. These data suggest that several agents, including rotavirus, can remain viable on contaminated surfaces long enough to be transmitted to susceptible children. This finding helps explain why rotavirus shows a mode of spread like that of parasitic and bacterial agents within day care center settings.     

Survival and detection of rotaviruses on environmental surfaces in day care centers

Previously, we demonstrated that children in day care centers commonly experience diarrhea due to rotavirus, giardia, and bacterial pathogens. Multiple agents frequently coexist, and the environment is heavily contaminated with enteric bacteria during outbreaks. A study of environmental surface contamination with rotavirus was performed during three non-outbreak periods. Of 25 samples collected from environmental surfaces and teachers hands at a day care center, 4 (16%) were positive for rotavirus antigen when a fluorescence assay was used. We also examined the survival of two animal viruses, rotavirus SA-11 and poliovirus type 1, and bacteriophage 12 on similar environmental surfaces in a laboratory. Poliovirus type 1 and bacteriophage f2 were more resistant to drying than rotavirus SA-11 and could be recovered after a 90-min exposure on a dry surface. Rotavirus SA-11 could be detected for 30 min. All three viruses survived longer when they were suspended in fecal material than when they were suspended in distilled water. These data suggest that several agents, including rotavirus, can remain viable on contaminated surfaces long enough to be transmitted to susceptible children. This finding helps explain why rotavirus shows a mode of spread like that of parasitic and bacterial agents within day care center settings.     

Optimising diquat use for submerged aquatic weed management

An experimentally derived prediction tool is under development which aims to assess potential deactivation of diquat caused by water and deposits on plant leaf surfaces in New Zealand water bodies, where aquatic weeds are targeted for diquat treatment. Optimising the use and success of diquat is important not only in managing public confidence in the use of aquatic herbicides, but also in minimising financial risk from failed treatments. Our approach focuses on characterising lake water quality and plant condition factors in these lakes to identify parameters that might be useful indicators of diquat deactivation potential. Water samples have been collected at 3-month intervals from lakes receiving large scale treatment for weed control. Samples have been analysed for turbidity, suspended solids, chlorophyll a, conductivity and dissolved anions. Samples have also been spiked with 1 mg l⁻¹ diquat to measure loss from adsorption and/or absorption. Shoot samples were also collected from targeted weed species at each sampling site and the amount of organic and inorganic deposits on plants has been measured and then added to a second diquat spiked sample to assess potential additional diquat loss from these deposits. Our results have shown deactivation from deposits on plant surfaces which is highly correlated with turbidity, including inorganic suspended solids and total suspended solids. A plant “dirtiness” scale has been devised to help predict the likely success or risk of diquat failure prior to any decision to proceed with treatment. Deactivation in water was only weakly linked to total suspended solids. Our failure to find significant correlation with the water quality factors measured may reflect the need for more detailed analysis of the particle size and composition of suspended solids and future research will address these issues.     

The use of sedimentation field-flow fractionation to study suspended particulate matter

The current and potential uses of sedimentation field-flow fractionation (SdFFF) for characterizing suspended particulate matter (SPM) from natural waters is reviewed. Suitable sample preparation methods and run conditions are given which enable the particle size distribution of aquatic SPM to be determined. Samples collected from different natural waters display quite distinct differences in the shape of their particle size distribution.One of the major advantages of this high resolution separation technique is that fractions of specific size ranges can be collected for characterization by other analytical methods. This has been illustrated in this work with scanning electron microscopy and EDAX elemental analysis data. The potential to extend this approach using other characterization techniques such as inductively coupled-plasma mass spectrometry and X-ray diffraction is discussed.A method has been developed for combining adsorption experiments with SdFFF separations that enables the distributions of both the amount adsorbed and the surface adsorption density across the SPM size range to be determined with good resolution. This approach is illustrated by the adsorption of the herbicide glyphosate to two estuarine SPM samples.     

Particulate matter composition and bacterial distribution in Terra Nova Bay (Antarctica) during summer 1989–1990

Spatial distributions of particulate organic matter (POM) and microbes were investigated during the summer of 1989–1990 in the coastal waters of Terra Nova Bay (Antarctica). The elemental (organic carbon and nitrogen) and biochemical (lipids, proteins, carbohydrates, DNA and RNA) composition of organic matter was related to bacterioplankton abundance, and pico-phytoplankton density. The ATP concentrations were also measured to gather information about the relationships between particulate matter composition and microbial distribution in Antarctic waters. Total seston was characterized by little spatial variation and was unrelated to the distance from the coast. Suspended particulate matter included some terrestrial components but was mostly composed of autochthonous material. POM was characterized by a uniform distribution and homogeneous composition (mostly of phytoplanktonic origin), and was associated with a relatively scarce microbial community characterized at the surface by high picophytoplankton density. The increase with depth of the living carbon fraction suggested an increase in the microheterotrophic community in the deeper water layers. A significant positive relationship between total bacterioplankton density, and carbohydrate and RNA concentrations was found. Similar significant relationships between pico-phytoplankton abundance and lipids, proteins, carbohydrates and nucleic acids were observed. On the basis of the close coupling found between microbiological and chemical compartments, it seems that, in Terra Nova Bay, bacterial distribution depends on suspended matter and in particular to the labile fraction of the organic detritus.     

Ammonia-oxidizing bacteria in a chloraminated distribution system: seasonal occurrence, distribution and disinfection resistance.

Nitrification in chloraminated drinking water can have a number of adverse effects on water quality, including a loss of total chlorine and ammonia-N and an increase in the concentration of heterotrophic plate count bacteria and nitrite. To understand how nitrification develops, a study was conducted to examine the factors that influence the occurrence of ammonia-oxidizing bacteria (AOB) in a chloraminated distribution system. Samples were collected over an 18-month period from a raw-water source, a conventional treatment plant effluent, and two covered, finished-water reservoirs that previously experienced nitrification episodes. Sediment and biofilm samples were collected from the interior wall surfaces of two finished-water pipelines and one of the covered reservoirs. The AOB were enumerated by a most-probable-number technique, and isolates were isolated and identified. The resistance of naturally occurring AOB to chloramines and free chlorine was also examined. The results of the monitoring program indicated that the levels of AOB, identified as members of the genus Nitrosomonas, were seasonally dependent in both source and finished waters, with the highest levels observed in the warm summer months. The concentrations of AOB in the two reservoirs, both of which have floating covers made of synthetic rubber (Hypalon; E.I. du Pont de Nemours & Co., Inc., Wilmington, Del.), had most probable numbers that ranged from less than 0.2 to greater than 300/ml and correlated significantly with temperature and levels of heterotrophic plate count bacteria. No AOB were detected in the chloraminated reservoirs when the water temperature was below 16 to 18 degrees C. The study indicated that nitrifiers occur throughout the chloraminated distribution system. Higher concentrations of AOB were found in the reservoir and pipe sediment materials than in the pipe biofilm samples. The AOB were approximately 13 times more resistant to monochloramine than to free chlorine. After 33 min of exposure to 1.0 mg of monochloramine per liter (pH 8.2, 23 degrees C), 99% of an AOB culture was inactivated. The amounts of this disinfectant that are currently used (1.5 mg/liter at a 3:1 ratio of chlorine to ammonia-N) may be inadequate to control the growth of these organisms in the distribution system.     

Isolation of enteroviruses from water, suspended solids, and sediments from Galveston Bay: survival of poliovirus and rotavirus adsorbed to sediments.

The distribution and quantitation of enteroviruses among water, suspended solids, and compact sediments in a polluted estuary are described. Samples were collected sequentially from water, suspended solids, fluffy sediments (uppermost layer of bottom sediments), and compact sediment. A total of 103 samples were examined of which 27 (26%) were positive for virus. Polioviruses were recovered most often, followed by coxsackie B viruses and echoviruses 7 and 29. Virus was found most often attached to suspended solids: 72% of these samples were positive, whereas only 14% of water samples without solids yielded virus. Fluffy sediments yielded virus in 47% of the samples, whereas only 5% of compact bottom-sediment samples were positive. When associated with solids, poliovirus and rotavirus retained their infectious quality for 19 days. The same viruses remained infectious for only 9 days when freely suspended in seawater. Collection of suspended solids at ambient water pH appears to be very useful for the detection of virus; it has advantages over collecting and processing large volumes of water, with accompanying pH adjustment and salt addition for processing.     

Isolation of enteroviruses from water, suspended solids, and sediments from Galveston Bay: survival of poliovirus and rotavirus adsorbed to sediments

The distribution and quantitation of enteroviruses among water, suspended solids, and compact sediments in a polluted estuary are described. Samples were collected sequentially from water, suspended solids, fluffy sediments (uppermost layer of bottom sediments), and compact sediment. A total of 103 samples were examined of which 27 (26%) were positive for virus. Polioviruses were recovered most often, followed by coxsackie B viruses and echoviruses 7 and 29. Virus was found most often attached to suspended solids: 72% of these samples were positive, whereas only 14% of water samples without solids yielded virus. Fluffy sediments yielded virus in 47% of the samples, whereas only 5% of compact bottom-sediment samples were positive. When associated with solids, poliovirus and rotavirus retained their infectious quality for 19 days. The same viruses remained infectious for only 9 days when freely suspended in seawater. Collection of suspended solids at ambient water pH appears to be very useful for the detection of virus; it has advantages over collecting and processing large volumes of water, with accompanying pH adjustment and salt addition for processing.     

Identification of bacteria in biofilm and bulk water samples from a nonchlorinated model drinking water distribution system: detection of a large nitrite-oxidizing population associated with Nitrospira spp

In a model drinking water distribution system characterized by a low assimilable organic carbon content (<10 microg/liter) and no disinfection, the bacterial community was identified by a phylogenetic analysis of rRNA genes amplified from directly extracted DNA and colonies formed on R2A plates. Biofilms of defined periods of age (14 days to 3 years) and bulk water samples were investigated. Culturable bacteria were associated with Proteobacteria and Bacteriodetes, whereas independently of cultivation, bacteria from 12 phyla were detected in this system. These included Acidobacteria, Nitrospirae, Planctomycetes, and Verrucomicrobia, some of which have never been identified in drinking water previously. A cluster analysis of the population profiles from the individual samples divided biofilms and bulk water samples into separate clusters (P = 0.027). Bacteria associated with Nitrospira moscoviensis were found in all samples and encompassed 39% of the sequenced clones in the bulk water and 25% of the biofilm community. The close association with Nitrospira suggested that a large part of the population had an autotrophic metabolism using nitrite as an electron donor. To test this hypothesis, nitrite was added to biofilm and bulk water samples, and the utilization was monitored during 15 days. A first-order decrease in nitrite concentration was observed for all samples with a rate corresponding to 0.5 x 10(5) to 2 x 10(5) nitrifying cells/ml in the bulk water and 3 x 10(5) cells/cm(2) on the pipe surface. The finding of an abundant nitrite-oxidizing microbial population suggests that nitrite is an important substrate in this system, potentially as a result of the low assimilable organic carbon concentration. This finding implies that microbial communities in water distribution systems may control against elevated nitrite concentrations but also contain large indigenous populations that are capable of assisting the depletion of disinfection agents like chloramines.     

Detection of Escherichia coli in biofilms from pipe samples and coupons in drinking water distribution networks

Fluorescence in situ hybridization (FISH) was used for direct detection of Escherichia coli on pipe surfaces and coupons in drinking water distribution networks. Old cast iron main pipes were removed from water distribution networks in France, England, Portugal, and Latvia, and E. coli was analyzed in the biofilm. In addition, 44 flat coupons made of cast iron, polyvinyl chloride, or stainless steel were placed into and continuously exposed to water on 15 locations of 6 distribution networks in France and Latvia and examined after 1 to 6 months exposure to the drinking water. In order to increase the signal intensity, a peptide nucleic acid (PNA) 15-mer probe was used in the FISH screening for the presence or absence of E. coli on the surface of pipes and coupons, thus reducing occasional problems of autofluorescence and low fluorescence of the labeled bacteria. For comparison, cells were removed from the surfaces and examined with culture-based or enzymatic (detection of beta-d-glucuronidase) methods. An additional verification was made by using PCR. Culture method indicated presence of E. coli in one of five pipes, whereas all pipes were positive with the FISH methods. E. coli was detected in 56% of the coupons using PNA FISH, but no E. coli was detected using culture or enzymatic methods. PCR analyses confirmed the presence of E. coli in samples that were negative according to culture-based and enzymatic methods. The viability of E. coli cells in the samples was demonstrated by the cell elongation after resuscitation in low-nutrient medium supplemented with pipemidic acid, suggesting that the cells were present in an active but nonculturable state, unable to grow on agar media. E. coli contributed to ca. 0.001 to 0.1% of the total bacterial number in the samples. The presence and number of E. coli did not correlate with any of physical and/or chemical characteristic of the drinking water (e.g., temperature, chlorine, or biodegradable organic matter concentration). We show here that E. coli is present in the biofilms of drinking water networks in Europe. Some of the cells are metabolically active but are often not detected due to limitations of traditionally used culture-based methods, indicating that biofilm should be considered as a reservoir that must be investigated further in order to evaluate the risk for human health.     

Analysis of the Velocity Distribution in Partially-Filled Circular Pipe Employing the Principle of Maximum Entropy

The flow velocity distribution in partially-filled circular pipe was investigated in this paper. The velocity profile is different from full-filled pipe flow, since the flow is driven by gravity, not by pressure. The research findings show that the position of maximum flow is below the water surface, and varies with the water depth. In the region of near tube wall, the fluid velocity is mainly influenced by the friction of the wall and the pipe bottom slope, and the variation of velocity is similar to full-filled pipe. But near the free water surface, the velocity distribution is mainly affected by the contractive tube wall and the secondary flow, and the variation of the velocity is relatively small. Literature retrieval results show relatively less research has been shown on the practical expression to describe the velocity distribution of partially-filled circular pipe. An expression of two-dimensional (2D) velocity distribution in partially-filled circular pipe flow was derived based on the principle of maximum entropy (POME). Different entropies were compared according to fluid knowledge, and non-extensive entropy was chosen. A new cumulative distribution function (CDF) of partially-filled circular pipe velocity in terms of flow depth was hypothesized. Combined with the CDF hypothesis, the 2D velocity distribution was derived, and the position of maximum velocity distribution was analyzed. The experimental results show that the estimated velocity values based on the principle of maximum Tsallis wavelet entropy are in good agreement with measured values.     

大辽河水系表层水中多环芳烃的污染特征

采用GC/MS对大辽河水系的浑河、太子河和大辽河表层水和悬浮物中的多环芳烃 (PAHs) 进行了定量分析,探讨了大辽河水系表层水和悬浮物中多环芳烃分布特征与来源.结果表明,水样和悬浮颗粒物中PAHs总量浓度分布范围分别为：水样946.1～13 448.5 ng·L^-1;悬浮颗粒物317.5～238 518.7 ng·g^-1.多环芳烃的浓度分布表现为太子河>大辽河>浑河,靠近工业区的PAHs浓度明显高于城市和非工业区.水样中PAHs以3～5环为主,悬浮颗粒物样中PAHs以2环为主.PAHs特定分子比率分析表明,大辽河水系受到石油输入和热解的复合PAH污染,采样站位附近石油化工和钢铁工业是PAHs的主要来源.与世界其他河流和海洋地区相比,水和悬浮颗粒物中污染浓度较高,具有一定的生态风险.     

Effectiveness of Antifouling Coatings and Water Flow in Controlling Attachment of the Nuisance Mussel Limnoperna fortunei

Various antifouling substrata were tested for their effectiveness in inhibiting attachment of Limnoperna fortunei. Field experiments revealed that surface properties affected the antifouling capabilities of nontoxic substrata. Antifouling capabilities were observed for three silicone resin-based coatings with smooth surfaces (<30 w m roughness) and low surface free energy of the hydrogen bonding force component. A further three silicone resin-based coatings tested, as well as other types of nontoxic coatings, did not show any antifouling capabilities. The percentages of juvenile mussels that attached in laboratory experiments correlated with the settling densities of mussels in the field experiments better than those based on adult mussels. This suggests that laboratory experiments with juveniles may be effective as short term preliminary assays to select promising materials/coatings for longer term field experiments. Mussel abundance surveys within a water transmission pipe and pipe current velocity simulation revealed that less infestation was observed in the areas with a wall-vicinity fluid velocity of >1.3 m s m 1 . Conversely, pipe surfaces with flows of <1.2 m s m 1 were heavily fouled by L. fortunei .     

Association between phosphorus and suspended solids in an Everglades treatment wetland dominated by submersed aquatic vegetation

Restoration of the Everglades requires reduction of total phosphorus (TP) in the influent run-off from the Everglades agricultural area (EAA). The Everglades nutrient removal project tested phosphorus (P) - removal efficiencies of several treatment wetland cells. The best TP reduction has occurred within the submersed aquatic vegetation (SAV) - dominated treatment Cell 4. A significant proportion of the P reduction in Cell 4 over several years has been in the form of particulate P (PP). This study was conducted to (i) determine and compare the components of suspended solids in the Cell 4 influent and effluent waters, and (ii) investigate associations between PP and individual particulate components. Identification and quantification of components were accomplished using X-ray diffraction, thermogravimetry, scanning electron microscopy, and energy dispersive X-ray elemental analysis. The dominant particulate components in the Cell 4 water column are organic matter (OM), biogenic Si (predominantly diatom frustules), and calcite. Concentrations of PP, suspended solids, and particulate OM were greater at the Cell 4 inflow than at the outflow; consistent differences between particulate calcite in the influent vs. the effluent were not found. PP was positively correlated with particulate OM, but was not correlated with calcite. Data suggest that particulate OM, including microbial cells, plays an important role in P transport from the EAA. Possibly, a shift from planktonic to periphytic microbial distribution contributes to PP reduction. The importance of planktonic organisms as vectors of P in Everglades water warrants further study.     

A pilot study of bacteriological population changes through potable water treatment and distribution

This pilot study compares the compositions of bacterial biofilms in pipe networks supplied with water containing either high levels of biodegradable organic matter (BOM) or low levels of BOM (conventionally or biologically treated, respectively). The Microbial Identification System for fatty acid analysis was utilized in this study to identify a large number of organisms (>1,400) to determine population changes in both conventionally and biologically treated water and biofilms. Data generated during this study indicated that suspended bacteria have little impact on biofilms, and despite treatment (conventional or biological), suspended microbial populations were similar following disinfection. Prechlorination with free chlorine resulted not only in reduced plate count values but also in a dramatic shift in the composition of the bacterial population to predominately gram-positive bacteria. Chlorination of biologically treated water produced the same shifts toward gram-positive bacteria. Removal of assimilable organic carbon by the biologically active filters slowed the rate of biofilm accumulation, but biofilm levels were similar to those found in conventionally treated water within several weeks. Iron pipes stimulated the rate of biofilm development, and bacterial levels on disinfected iron pipes exceeded those for chlorinated polyvinyl chloride pipes. The study showed that the iron pipe surface dramatically influenced the composition, activity, and disinfection resistance of biofilm bacteria.     

A Pilot Study of Bacteriological Population Changes through Potable Water Treatment and Distribution

This pilot study compares the compositions of bacterial biofilms in pipe networks supplied with water containing either high levels of biodegradable organic matter (BOM) or low levels of BOM (conventionally or biologically treated, respectively). The Microbial Identification System for fatty acid analysis was utilized in this study to identify a large number of organisms (>1,400) to determine population changes in both conventionally and biologically treated water and biofilms. Data generated during this study indicated that suspended bacteria have little impact on biofilms, and despite treatment (conventional or biological), suspended microbial populations were similar following disinfection. Prechlorination with free chlorine resulted not only in reduced plate count values but also in a dramatic shift in the composition of the bacterial population to predominately gram-positive bacteria. Chlorination of biologically treated water produced the same shifts toward gram-positive bacteria. Removal of assimilable organic carbon by the biologically active filters slowed the rate of biofilm accumulation, but biofilm levels were similar to those found in conventionally treated water within several weeks. Iron pipes stimulated the rate of biofilm development, and bacterial levels on disinfected iron pipes exceeded those for chlorinated polyvinyl chloride pipes. The study showed that the iron pipe surface dramatically influenced the composition, activity, and disinfection resistance of biofilm bacteria.