Quick Answer: Bacteria found in tap water originate from multiple sources — source water, treatment plant effluent, distribution pipe biofilms, and premise plumbing. SourceTracker microbial community analysis can identify the dominant contributors, enabling targeted intervention in unchlorinated or low-chlorine systems where regrowth is most problematic.
Gang Liu; Ya Zhang; Mark, E. van der; Magic-Knezev, A.; Pinto, A.; Bogert, B. van den; Wentso Liu; Meer, W. van der; Medema, G
Water Research, 138 86-96; 10.1016/j.watres.2018.03.0432018
Abstract
The general consensus is that the abundance of tap water bacteria is greatly influenced by water purification and distribution. Those bacteria that are released from biofilm in the distribution system are especially considered as the major potential risk for drinking water bio-safety. For the first time, this full-scale study has captured and identified the proportional contribution of the source water, treated water, and distribution system in shaping the tap water bacterial community based on their microbial community fingerprints using the Bayesian “SourceTracker” method. The bacterial community profiles and diversity analyses illustrated that the water purification process shaped the community of planktonic and suspended particle-associated bacteria in treated water. The bacterial communities associated with suspended particles, loose deposits, and biofilm were similar to each other, while the community of tap water planktonic bacteria varied across different locations in distribution system. The microbial source tracking results showed that there was not a detectable contribution of source water to bacterial community in the tap water and distribution system. The planktonic bacteria in the treated water was the major contributor to planktonic bacteria in the tap water (17.7–54.1%). The particle-associated bacterial community in the treated water seeded the bacterial community associated with loose deposits (24.9–32.7%) and biofilm (37.8–43.8%) in the distribution system. In return, the loose deposits and biofilm showed a significant influence on tap water planktonic and particle-associated bacteria, which were location dependent and influenced by hydraulic changes. This was revealed by the increased contribution of loose deposits to tap water planktonic bacteria (from 2.5% to 38.0%) and an increased contribution of biofilm to tap water particle-associated bacteria (from 5.9% to 19.7%) caused by possible hydraulic disturbance from proximal to distal regions. Therefore, our findings indicate that the tap water bacteria could possibly be managed by selecting and operating the purification process properly and cleaning the distribution system effectively.
https://www.sciencedirect.com/science/article/pii/S0043135418302392?via%3Dihub
The post Assessing the origin of bacteria in tap water and distribution system in an unchlorinated drinking water system by SourceTracker using microbial community fingerprints appeared first on Facts About Water.
Source: Water Feed
What flow rates are available for emergency water treatment?
AMPAC USA's emergency systems range from 1,500 GPD portable units to 50,000+ GPD trailer-mounted systems. Military-specification units are available for forward operating base deployment, producing potable water meeting EPA and WHO drinking water standards from virtually any source.
Are emergency RO systems suitable for disaster relief operations?
Yes. AMPAC USA's emergency systems are used by FEMA, the U.S. military, and international NGOs for disaster relief. They treat flood water, contaminated groundwater, and brackish sources, removing bacteria, viruses, and chemical contaminants to produce safe drinking water on-site.
What power sources can emergency water purification systems use?
AMPAC USA's emergency systems can run on generator power (120/240V or 480V 3-phase), solar panels with battery backup, or vehicle power take-off (PTO). Low-power models consume as little as 0.5 kW, making them viable for off-grid deployment.
How durable are military-grade water purification systems?
AMPAC USA's military systems are built to MIL-SPEC standards with stainless steel frames, powder-coated components, and UV-resistant materials. They are designed to operate in temperatures from -20°F to 120°F and are vibration-tested for transport in military vehicles.
Conclusion
This post highlighted how emergency and military-grade water purification systems provide safe drinking water rapidly in the most challenging field conditions. For organizations requiring deployable water treatment capability, AMPAC USA engineers portable and trailer-mounted systems built to perform wherever they are needed. Contact our team at [email protected] or (909) 548-4900 to discuss your emergency water treatment requirements.
Tracing Bacterial Sources in Distribution Systems
Even well-treated drinking water can contain bacteria at the consumer tap — a reality that motivates extensive research into bacterial ecology in distribution systems. Liu et al. (Water Research, 2018) applied SourceTracker, a Bayesian statistical tool originally developed for human microbiome research, to fingerprint microbial communities across an unchlorinated Dutch water system. Their findings revealed that pipe biofilm — not source water or treatment effluent — was the dominant contributor to bacteria at consumer taps, particularly in older cast iron pipe sections with higher surface area and corrosion products.
Unchlorinated water systems, common in parts of Northern Europe, provide natural settings to study bacterial dynamics without the confounding effect of residual disinfectants. In these systems, bacteria establish stable biofilms within days of treatment plant discharge, with community composition shifting based on pipe material, age, hydraulic residence time, and organic carbon availability. Proteobacteria (Alphaproteobacteria and Betaproteobacteria) typically dominate, though opportunistic pathogens including Legionella and Pseudomonas can constitute a measurable fraction under favorable conditions.
For water utilities and facility managers, this research has direct practical implications. Systems maintaining disinfectant residuals suppress but do not eliminate biofilm bacteria — high-flow events or pressure transients can slough biofilm into the bulk water. Point-of-use treatment (POU) systems including reverse osmosis, ultrafiltration (0.02 micron), and UV disinfection (40 mJ/cm²) provide the final barrier against residual bacteria regardless of distribution system dynamics. AMPAC USA designs POU and point-of-entry (POE) systems for facilities where distribution system integrity cannot be guaranteed.
Q: What is SourceTracker and how is it used for water quality?
A: SourceTracker is a Bayesian source-tracking tool that uses microbial community composition (16S rRNA gene sequencing) to estimate the proportional contribution of defined source environments to a mixed sample — in this case, identifying where tap water bacteria originate.
Q: Are bacteria in tap water dangerous?
A: Most bacteria in treated tap water are non-pathogenic environmental bacteria. However, opportunistic pathogens like Legionella, Pseudomonas aeruginosa, and Mycobacteria can colonize distribution systems and pose risk to immunocompromised individuals.
Q: How does pipe material affect bacterial growth in water systems?
A: Pipe material significantly influences biofilm formation. Unlined cast iron and concrete pipes provide rough surfaces and release corrosion products that support bacterial growth. Smooth plastic pipes (PVC, HDPE) and stainless steel have lower biofilm formation potential.
Q: Do chlorinated systems have fewer bacteria at the tap?
A: Chlorination suppresses but does not eliminate bacteria in distribution systems. Residual chlorine (0.2–0.5 mg/L) inhibits bulk water growth but does not fully penetrate or eliminate established biofilms. Unchlorinated systems have higher bacterial concentrations but may have similar biofilm community diversity.
Q: What is the difference between HPC and coliform counts in water testing?
A: HPC (heterotrophic plate count) measures the total cultivable bacterial population and indicates overall microbial activity. Total coliform and E. coli tests are regulatory indicators specifically targeting fecal contamination. High HPC without coliforms indicates aesthetic or regrowth issues rather than direct fecal contamination.
Q: How can building managers reduce bacteria in premise plumbing?
A: Regular flushing of low-use fixtures, maintaining water heater temperatures above 60°C, replacing lead service lines and old galvanized pipes, and installing point-of-use filters all reduce bacterial exposure at the tap within buildings.
Tracing Bacterial Sources in Distribution Systems
Even well-treated drinking water can contain bacteria at the consumer tap — a reality that motivates extensive research into bacterial ecology in distribution systems. Liu et al. (Water Research, 2018) applied SourceTracker, a Bayesian statistical tool originally developed for human microbiome research, to fingerprint microbial communities across an unchlorinated Dutch water system. Their findings revealed that pipe biofilm — not source water or treatment effluent — was the dominant contributor to bacteria at consumer taps, particularly in older cast iron pipe sections with higher surface area and corrosion products.
Unchlorinated water systems, common in parts of Northern Europe, provide natural settings to study bacterial dynamics without the confounding effect of residual disinfectants. In these systems, bacteria establish stable biofilms within days of treatment plant discharge, with community composition shifting based on pipe material, age, hydraulic residence time, and organic carbon availability. Proteobacteria (Alphaproteobacteria and Betaproteobacteria) typically dominate, though opportunistic pathogens including Legionella and Pseudomonas can constitute a measurable fraction under favorable conditions.
For water utilities and facility managers, this research has direct practical implications. Systems maintaining disinfectant residuals suppress but do not eliminate biofilm bacteria — high-flow events or pressure transients can slough biofilm into the bulk water. Point-of-use treatment (POU) systems including reverse osmosis, ultrafiltration (0.02 micron), and UV disinfection (40 mJ/cm²) provide the final barrier against residual bacteria regardless of distribution system dynamics. AMPAC USA designs POU and point-of-entry (POE) systems for facilities where distribution system integrity cannot be guaranteed.
Q: What is SourceTracker and how is it used for water quality?
A: SourceTracker is a Bayesian source-tracking tool that uses microbial community composition (16S rRNA gene sequencing) to estimate the proportional contribution of defined source environments to a mixed sample — in this case, identifying where tap water bacteria originate.
Q: Are bacteria in tap water dangerous?
A: Most bacteria in treated tap water are non-pathogenic environmental bacteria. However, opportunistic pathogens like Legionella, Pseudomonas aeruginosa, and Mycobacteria can colonize distribution systems and pose risk to immunocompromised individuals.
Q: How does pipe material affect bacterial growth in water systems?
A: Pipe material significantly influences biofilm formation. Unlined cast iron and concrete pipes provide rough surfaces and release corrosion products that support bacterial growth. Smooth plastic pipes (PVC, HDPE) and stainless steel have lower biofilm formation potential.
Q: Do chlorinated systems have fewer bacteria at the tap?
A: Chlorination suppresses but does not eliminate bacteria in distribution systems. Residual chlorine (0.2–0.5 mg/L) inhibits bulk water growth but does not fully penetrate or eliminate established biofilms. Unchlorinated systems have higher bacterial concentrations but may have similar biofilm community diversity.
Q: What is the difference between HPC and coliform counts in water testing?
A: HPC (heterotrophic plate count) measures the total cultivable bacterial population and indicates overall microbial activity. Total coliform and E. coli tests are regulatory indicators specifically targeting fecal contamination. High HPC without coliforms indicates aesthetic or regrowth issues rather than direct fecal contamination.
Q: How can building managers reduce bacteria in premise plumbing?
A: Regular flushing of low-use fixtures, maintaining water heater temperatures above 60°C, replacing lead service lines and old galvanized pipes, and installing point-of-use filters all reduce bacterial exposure at the tap within buildings.
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