Potable Water Systems Research Articles

Existence of Thermotolerant and Salt-Loving Diarrheagenic Vibrio alginolyticus in Non-Saline Potable Water System: A Novel Finding from India.

We present a novel report of abundance of halophilic Vibrio alginolyticus with thermotolerant and enterotoxigenic characteristics from community water system of an inland-focus of India causing diarrheal outbreak as an index pathogen. Though, Vibrio alginolyticus causing diarrhea after exposure to marine water and consumption of seafood was reported globally, its existence in non-saline drinking-water sources with pathogenic viability was unknown. A 'matched-pair-case-control' study identified the primary source of V. alginolyticus infection as 'tap-water' distributed by the municipality, used for drinking (MOR: 8.33; 95% CI 2.51-27.6) and household chores (MOR: 3.75; 95% CI 1.24-11.3). Cardinal toxin gene 'tdh' and other pathogenicity markers viz.tlh, vppC, toxR, VPI, T3SS1 and sxt were detected in V. alginolyticus isolates. Expression potential of the hemolytic genes are demonstrated by hemolysis assay and transcriptome analysis. Altogether 30.55% of isolates exhibited strong hemolytic potential in vitro. RT-PCR revealed uninterrupted virulence gene expression in outbreak strains under heat stress. Surprisingly, ~ 100% of V. alginolyticus from the outbreak focus were sensitive/partially sensitive to all group of antibiotics except β-lactums, carbapenem and quinolones. High drug-sensitivity suggested lack of previous human gut exposure and indicated a fresh dissemination from the environmental niche to the community domain. The maximum likelihood phylogeny depicted multiple clades in V. alginolyticus strains from Pan India sources. Isolated outbreak strains shared common ancestry with the strains from nearby riverine system, a source of 'drinking water' supplied to the affected community, confirming its environmental origin. V. alginolyticus, traditionally a fish-pathogen, is steadily gaining an emerging epidemiological relevance alongside other waterborne diarrheagenic bacteria and its 'thermotolerant' attribute poses additional threat under the canvas of climate change.

Two-year evaluation of Legionella in an aging residential building: Assessment of multiple potable water remediation approaches

Legionella is an opportunistic waterborne pathogen that is difficult to eradicate in colonized drinking water pipes. Legionella control is further challenged by aging water infrastructure and lack of evidence-based guidance for building treatment. This study assessed multiple premise water remediation approaches designed to reduce Legionella pneumophila within a residential building located in an aging, urban drinking water system over a two-year period. Samples (n = 745) were collected from hot and cold-water lines and quantified via most probable number culture. Building-level treatment approaches included three single heat shocks, three single chemical shocks, and continuous low-level chemical disinfection in the potable water system. The building was highly colonized with L. pneumophila with 71 % L. pneumophila positivity. Single heat shocks had a statistically significant L. pneumophila reduction one day post treatment but no significant L. pneumophila reduction at one week, two weeks, and four weeks post treatment. The first two chemical shocks resulted in statistically significant L. pneumophila reduction at two days and four weeks post treatment, but there was a significant L. pneumophila increase at four weeks following the third chemical shock. Continuous low-level chemical disinfection resulted in statistically significant L. pneumophila reduction at ten weeks post treatment implementation. This demonstrates that in a building highly colonized with L. pneumophila, sustained remediation is best achieved using continuous low-level chemical treatment.

For the occurrence of PPCPs from source to tap: A novel approach modified in terms of sample preservation and SPE cartridge to monitor PPCPs in our water supply

BackgroundThe ongoing infusion of pharmaceutical and personal care products (PPCPs) into ecosystems sustains a perpetual life cycle and leads to multi-generational exposures. Limited understanding of their environmental impact and their intrinsic ability to induce physiological effect in humans, even at low doses, pose great risks to human health. Few scholarly works have conducted systematic research into the occurrence of PPCPs within potable water systems. Concurrently, the associated monitoring techniques have not been comprehensively examined with regards to the specific nature of drinking water, namely whether the significant presence of disinfectants may influence the detection of PPCPs. ResultsA modified approach in terms of detailed investigation of sample preservation and optimization of an in-lab fabricated solid phase extraction (SPE) cartridge filled with DVB-VP and PS-DVB sorbent was proposed. Favorable methodological parameters were achieved, with correlation coefficients spanning from 0.9866 to 0.9998. The LODs of the PPCPs fluctuated from 0.001 to 2 μg L−1, while the LOQs varied from 0.002 to 5 μg L−1. The analysis of spiked samples disclosed a methodological precision of 2.31–9.86 % and a recovery of 52.4–119 %. We utilized the established method for analyzing 14 water samples of three categories (source water, finished water and tap water) from five centralized water supply plants. A total of 24 categories encompassing 72 PPCPs were detected, with the concentrations of PPCPs manifested a marked decrease from source water to finished water and finally to tap water. SignificanceOur research meticulously examined the enhancement and purification effects of widely used commercial SPE cartridges and suggested the use of in-lab fabricated SPE cartridges packed with DVB-VP and PS-DVB adsorbents. We also conducted a systematic evaluation of the need to incorporate ascorbic acid and sodium thiosulfate as preservatives for PPCP measurement, in consideration of the unique characteristics of drinking water matrices, specifically, the significant concentration levels of disinfectants. Furthermore, the proposed method was effectively employed to study the presence of PPCPs in source water, finished water, and tap water collected from centralized water supply plants.

Substrate Matters: Ionic Silver Alters Lettuce Growth, Nutrient Uptake, and Root Microbiome in a Hydroponics System.

Ionic silver (Ag+) is being investigated as a residual biocide for use in NASA spacecraft potable water systems on future crewed missions. This water will be used to irrigate future spaceflight crop production systems. We have evaluated the impact of three concentrations (31 ppb, 125 ppb, and 500 ppb) of ionic silver biocide solutions on lettuce in an arcillite (calcinated clay particle substrate) and hydroponic (substrate-less) growth setup after 28 days. Lettuce plant growth was reduced in the hydroponic samples treated with 31 ppb silver and severely stunted for samples treated at 125 ppb and 500 ppb silver. No growth defects were observed in arcillite-grown lettuce. Silver was detectable in the hydroponic-grown lettuce leaves at each concentration but was not detected in the arcillite-grown lettuce leaves. Specifically, when 125 ppb silver water was applied to a hydroponics tray, Ag+ was detected at an average amount of 7 μg/g (dry weight) in lettuce leaves. The increase in Ag+ corresponded with a decrease in several essential elements in the lettuce tissue (Ca, K, P, S). In the arcillite growth setup, silver did not impact the plant root zone microbiome in terms of alpha diversity and relative abundance between treatments and control. However, with increasing silver concentration, the alpha diversity increased in lettuce root samples and in the water from the hydroponics tray samples. The genera in the hydroponic root and water samples were similar across the silver concentrations but displayed different relative abundances. This suggests that ionic silver was acting as a selective pressure for the microbes that colonize the hydroponic water. The surviving microbes likely utilized exudates from the stunted plant roots as a carbon source. Analysis of the root-associated microbiomes in response to silver showed enrichment of metagenomic pathways associated with alternate carbon source utilization, fatty-acid synthesis, and the ppGpp (guanosine 3'-diphosphate 5'-diphosphate) stringent response global regulatory system that operates under conditions of environmental stress. Nutrient solutions containing Ag+ in concentrations greater than 31 ppb in hydroponic systems lacking cation-exchange capacity can severely impact crop production due to stunting of plant growth.

Bacterial community assessment of drinking water and downstream distribution systems in highland localities of Ecuador.

Bacterial communities in drinking water provide a gauge to measure quality and confer insights into public health. In contrast to urban systems, water treatment in rural areas is not adequately monitored and could become a health risk. We performed 16S rRNA amplicon sequencing to analyze the microbiome present in the water treatment plants at two rural communities, one city, and the downstream water for human consumption in schools and reservoirs in the Andean highlands of Ecuador. We tested the effect of water treatment on the diversity and composition of bacterial communities. A set of physicochemical variables in the sampled water was evaluated and correlated with the structure of the observed bacterial communities. Predominant bacteria in the analyzed communities belonged to Proteobacteria and Actinobacteria. The Sphingobium genus, a chlorine resistance group, was particularly abundant. Of health concern in drinking water reservoirs were Fusobacteriaceae, Lachnospiraceae, and Ruminococcaceae; these families are associated with human and poultry fecal contamination. We propose the latter families as relevant biomarkers for establishing local standards for the monitoring of potable water systems in highlands of Ecuador. Our assessment of bacterial community composition in water systems in the Ecuadorian highlands provides a technical background to inform management decisions.

Environmental Assessment and Monitoring of Heavy Metals in New York City Potable Water Systems: Case Study at Medgar Evers College, Correlation Analysis, and Public Health Impacts

Reinforced by this study, New York City has one of the cleanest water systems in the world. Medgar Evers College (MEC) serves 7000 students/1050 faculty/staff. Given that: (1) students/faculty/staff spend 20–30% of their daily time there; (2) potable water sources must abide by the EPA’s maximum contamination levels (MCLs); and (3) a detrimental impact on human health arises from violations to EPA’s water quality mandates, we quantified the abundance of 27 heavy metals (96 samples, N = 3) using MEC as a case study. Water was collected from all potable water sources, following EPA protocols for sample-matrix preparation, collection, and wet-chemical analysis. Linear polyethylene containers/caps were used to prevent sample contamination while the water samples were spiked with HNO3 (aq) for preservation. Heavy metal concentrations were quantified using New Jersey’s Meadowlands Environmental Research Institute’s Inductively Coupled Plasma-Mass Spectrometer (ICP-MS, Agilent 7700X) in no gas, and He flow modes. Ninety-five percent of sample concentration relative standard deviations (RSDs) reveal four distinct regions: (1) where one mode is more precise than the other, and sample data exhibit very good to excellent precision, RSD ≤ 15%; (2) despite being at low concentrations, measurements exhibit good to excellent precision, RSD ≤ 20%; (3) species concentrations ≥0.1 ppb very good to excellent precision is shown, RSD ≤ 15%; and (4) species at concentrations ≤ 10−3 ppb display fair to very poor precision, RSD ≥ 30%. All heavy metals complied with their respective EPA MCLs (except Fe). Over 90% of Fe sample concentrations were enhanced by up to about 30×. Two samples exhibited [Pb] = 13.7 (No gas mode, RSD = 3.32%) and 14.8 ppb (He mode, RSD = 0.75%), which is close to the EPA Primary MCL, 15 ppb. Based on EPA/WHO end-member equations, we estimate a 1/103 to 1/108 chance of cancer attainment from long-term exposure to the range of concentrations of heavy metals measured in this study.

Combatting biofilms in potable water systems: A comprehensive overview to ensuring industrial water safety.

Biofilm formation in industrial potable water systems, encompassing applications such as drinking, emergency showers, firefighting and sanitary appliances, presents a multifaceted challenge that has significant implications for both equipment efficiency and human health. These microbial communities, comprised of bacteria, fungi and protozoa, adhere to surfaces and are embedded within an extracellular matrix, primarily of polysaccharide origin. The formation and persistence of these biofilms can lead to reduced system efficiency and potential health risks due to microbial-induced corrosion, contamination and waterborne pathogens. This review delves into the physicochemical and microbial factors promoting biofilm growth in these systems and elucidates contemporary strategies for their control and eradication. By harnessing advanced methodologies, including state-of-the-art filtration, disinfection techniques and predictive monitoring, stakeholders can proactively address biofilm-related challenges. The emphasis of this comprehensive overview is on the interdisciplinary nature of biofilm growth, combining insights from microbiology, engineering and water chemistry to pave the way for an integrative approach to ensuring consistent industrial water quality.

EVALUATION AND STRUCTURAL MODELING OF 200 m3 CIRCULAR TANK SUPPORTED WITH SOFTWARE APPLICATION

Permanent constructions in drinking water systems are of primary use in the development of a population. The objective of this work was to perform a non-destructive surface evaluation and structural modeling of the 200 m3 supported tank under conditions in the town of Pomata, Peru. A sclerometer was used to determine the concrete strength of the circular wall and the lower base of the old tank. The structural evaluation of the old tank was carried out by applying the design tables of the Portland Cement Association (PCA) and modeling with reliable structural calculation software; likewise, in the old tank the spectral dynamic analysis was carried out with the design parameters of the Peruvian National Construction Regulations, structural standards E.020, E.030, E.050, E.060 and ACI 350-01, ACI 350-06. The same results were obtained for the annular and bending stresses in a static analysis using the PCA design tables. According to the technical evaluation of the old tank, which has a useful life of more than 20 years of use in the potable water system; a new tank with the same storage capacity and in the same location was proposed; in the static and dynamic spectral analysis the PCA tables and modeling with software were used; achieving similar results in both tanks. It was demonstrated that demolition is necessary.

Utility considerations in developing a galvanized iron water pipe management plan

AbstractGalvanized iron pipe (GIP) was once widely installed in publicly and privately owned potable water systems. This antiquated plumbing material can cause water discoloration from iron release, head loss resulting from corrosion scale buildup, and occasional problems with lead (Pb) release to drinking water. In this work, a GIP management framework for utilities is formulated via a literature review and several case studies. The GIP management plan is intended to guide water systems with understanding and addressing GIP issues while considering consumer expectations, corrosion control challenges, variable performance, and associated cost–benefit analysis for corrective actions.

Estimation of the Restoration Period of the Water Supply System in Lima, Peru, After a Scenario Earthquake

The restoration period of the water supply system in Lima, Peru, after a scenario earthquake was estimated in this study. To achieve the objective, the probabilistic assessment model for post-earthquake residual capacity of the utility lifeline system initially proposed by Nojima and Sugito (2005) and revised by following related studies was employed. The dataset of water distribution pipelines was provided by Potable Water and Sewer System Service in Lima, Peru (SEDAPAL), and the spatial distribution of ground motion with a moment magnitude of 8.6 was considered as a scenario earthquake in this study. The water disruption was anticipated to continue for approximately one month in certain districts of Lima, Peru. The estimated smallest water supplying ratio was 21.1% in Villa El Salvador after the scenario earthquake.

Characterizing Biofilm Interactions between Ralstonia insidiosa and Chryseobacterium gleum.

Ralstonia insidiosa and Chryseobacterium gleum are bacterial species commonly found in potable water systems, and these two species contribute to the robustness of biofilm formation in a model six-species community from the International Space Station (ISS) potable water system. Here, we set about characterizing the interaction between these two ISS-derived strains and examining the extent to which this interaction extends to other strains and species in these two genera. The enhanced biofilm formation between the ISS strains of R. insidiosa and C. gleum is robust to starting inoculum and temperature and occurs in some but not all tested growth media, and evidence does not support a soluble mediator or coaggregation mechanism. These findings shed light on the ISS R. insidiosa and C. gleum interaction, though such enhancement is not common between these species based on our examination of other R. insidiosa and C. gleum strains, as well as other species of Ralstonia and Chryseobacterium. Thus, while the findings presented here increase our understanding of the ISS potable water model system, not all our findings are broadly extrapolatable to strains found outside of the ISS. IMPORTANCE Biofilms present in drinking water systems and terminal fixtures are important for human health, pipe corrosion, and water taste. Here, we examine the enhanced biofilm of cocultures for two very common bacteria from potable water systems: Ralstonia insidiosa and Chryseobacterium gleum. While strains originally isolated on the International Space Station show enhanced dual-species biofilm formation, terrestrial strains do not show the same interaction properties. This study contributes to our understanding of these two species in both dual-culture and monoculture biofilm formation.

Prevalence and implications of microplastics in potable water system: An update

Synthetic plastics, which are lightweight, durable, elastic, mouldable, cheap, and hydrophobic, were originally invented for human convenience. However, their non-biodegradability and continuous accumulation at an alarming rate as well as subsequent conversion into micro/nano plastic scale structures via mechanical and physio-chemical degradation pose significant threats to living beings, organisms, and the environment. Various minuscule forms of plastics detected in water, soil, and air are making their passage into living cells. High temperature and ambient humidity increase the degradation potential of plastic polymers photo-catalytically under sunlight or UV-B radiations. Microplastics (MPs) of polyethylene terephthalate, polyethylene, polystyrene, polypropylene, and polyvinyl chloride have been detected in bottled water. These microplastics are entering into the food chain cycle, causing serious harm to all living organisms. MPs entering into the food chain are usually inert in nature, possessing different sizes and shapes. Once they enter a cell or tissue, it causes mechanical damage, induces inflammation, disturbs metabolism, and even lead to necrosis. Various generation routes, types, impacts, identification, and treatment of microplastics entering the water bodies and getting associated with various pollutants are discussed in this review. It emphasizes potential detection techniques like pyrolysis, gas chromatography-mass spectrometry (GC-MS), micro-Raman spectroscopy, and fourier transform infrared spectroscopy (FT IR) spectroscopy for microplastics from water samples.

An investigation of the seasonal relationships between meteorological factors, water quality, and sporadic cases of Legionnaires' disease in Washington, DC.

Since the discovery of Legionnaires' disease (LD), limited progress has been made in understanding the epidemiology of sporadic cases of LD. Outbreaks have confirmed that air conditioning and potable water systems can be sources of community-acquired LD. However, studying the association between water quality and LD incidence has been challenging due to the heterogeneity of water systems across large geographic areas. Furthermore, although seasonal trends in incidence have been linked to increased rainfall and temperatures, the large geographic units have posed similar difficulties. To address this issue, a retrospective ecological study was conducted in Washington, DC, from 2001 to 2019. The study identified aseasonal pattern of LD incidence, with the majority of cases occurring between June and December, peaking in August, October, and November. Increased temperature was found to be associated with LD incidence. In surface water, higher concentrations of manganese, iron, and strontium were positively associated with LD, while aluminum and orthophosphate showed a negative association. Intreatment plant water, higher concentrations of total organic carbon, aluminum, barium, and chlorine were positively associated with LD, while strontium, zinc, and orthophosphate showed a negative association. The results for orthophosphates and turbidity were inconclusive, indicating the need for further research.

Bituminous Geomembrane (BGM) in hot climates for hydraulic construction

This paper will explain the reinforced structure and key characteristics that make bituminous geomembranes (BGM) an interesting option for waterproofing hydraulic works in hot climate areas. For illustrating this, the paper will review some case studies where BGM was chosen due to its characteristics. In dam application, a project for a waterproofing of a dike in Saday (Djibouti) and a rock fill dam (42-m high) in France will be explained. For irrigation in reservoir and canal lining, a work in Goudel and a canal on laterite soil in Niamey (both in Niger) will described proving use of BGM in dry tropical climates. This paper will also review the construction of raw water storage ponds in Pirque (Chile) for the city of Santiago’s potable water system. A last project will be described on a large irrigation canal in Nagpur (India) where the Pench canal, located in the center of India, convey water from the Pench River to the surrounding agricultural areas. The old canal, originally made of concrete, collapsed due to the water seepage and the swelling clay underneath.

Resilience Analysis of Potable Water Service after Power Outages in the U.S. Virgin Islands.

The two Category-5 hurricanes that impacted the United States Virgin Islands in 2017 exposed critical infrastructure vulnerabilities that must be addressed. While the drinking water utility has first-hand knowledge about how the hurricanes affected their systems, the use of modeling and simulation tools can provide additional insight to aid investment planning and preparedness. This paper provides a case study on resilience analysis for the island's potable water systems subject to long term power outages. Power outage scenarios help quantify differences in water delivery, water quality, and water quantity during and after the disruption. The analysis helps illustrate important differences in system operations and recovery time across the islands. Results from this case study can be used to better understand how the system might behave during future disruptions, provide justification for investment, and provide recommendations to increase resilience of the system. The analysis framework can also be used by other utilities to explore vulnerability to long term power outages.

Bacterial bioburden and community structure of potable water used in the International Space Station

The control of microbes in manned spaceflight is essential to reducing the risk of infection and maintaining crew health. The primary issue is ensuring the safety of a potable water system, where simultaneous monitoring of microbial abundance and community structure is needed. In this paper, we develop a flow cytometry-based counting protocol targeting cellular flavin autofluorescence as a tool for rapid monitoring of bacterial cells in water. This was successfully applied to estimate the bacterial bioburden in the potable water collected from the International Space Station. We also demonstrate the efficacy of the MinION nanopore sequencer in rapidly characterizing bacterial community structure and identifying the dominant species. These monitoring protocols' rapidity and cost effectiveness would contribute to developing sustainable real-time surveillance of potable water in spaceflight.

Modulating the Asymmetry of the Active Layer in Pursuit of Nanofiltration Selectivity via Differentiating Interfacial Reactions of Piperazine.

Nanofiltration (NF), highly prospective for drinking water treatment, faces a challenge in simultaneously removing emerging contaminants while maintaining mineral salts, particularly divalent cations. To overcome this challenge, NF membranes possessing small pores concomitant with highly negatively charged surfaces were synthesized via a two-step fabrication strategy. The key is to generate a polyamide active layer having a loose and carboxyl group-abundant segment on top and a dense barrier segment underneath. This was achieved by restrained interfacial polymerization between trimesoyl chloride and partly protonated piperazine to form a highly depth-heterogeneous polyamide network, followed by second amidation in an organic environment to remove untethered polyamide fragments and associate malonyl chlorides with reserved amine groups to introduce more negative charges. Most importantly, on first-principle engineering the spatial architecture of the polyamide layer, amplifying asymmetric charge distribution was paired with the thinning of the vertical structure. The optimized membrane exhibits high salt/organic rejection selectivity and water permeance superior to most NF membranes reported previously. The rejections of eight emerging contaminants were in the range of 66.0-94.4%, much higher than the MgCl2 rejection of 41.1%. This new fabrication strategy, suitable for various diacyl chlorides, along with the new membranes so produced, offers a novel option for NF in potable water systems.

Legionella and the Role of Dissolved Oxygen in Its Growth and Inhibition: A Review

This review discusses the relationship between dissolved oxygen and Legionella growth. Growth of Legionella in building water systems is considered to pose a health risk and controlling it could benefit public health by reducing the number of healthcare and community acquired Legionnaires’ disease cases. Conditions known to encourage Legionella growth include low disinfectant concentrations, warm temperature, and water stagnation. Legionella is an obligate aerobe meaning its cellular respiration is inhibited under anaerobic conditions. Despite evidence from earlier published studies the importance of dissolved oxygen for the survival and growth of Legionella has received little attention from researchers and public health authorities. Modern measurement devices can reliably determine if dissolved oxygen concentrations in potable water and other building water systems are at levels capable of supporting Legionella growth or inhibiting its amplification. Removing dissolved oxygen from water can be achieved using gas transfer membrane contactors. Water with low dissolved oxygen levels interferes with Legionella’s cellular respiration by oxygen starvation, whereas disinfectants achieve the same effect by interfering with oxygen transport across the cell membrane. Ultimately, the same effect on Legionella growth may be achieved by reducing dissolved oxygen as treatment with oxidants, while avoiding the drawbacks of corrosion and disinfectant byproducts.

Experimental investigation of two novel arrangements of air gap membrane distillation module with heat recovery

Experimental investigations of an air gap membrane distillation (AGMD) unit were carried out to study the energy-saving by heat recovery. The spiral air gap membrane module in the water desalination unit was used. The unit was configured to operate in two novel arrangements and designed to minimize the loss of heat within the drains which maximize the unit productivity as well as the thermal efficiency. Water of salt concentrations 10,000 ppm and 20,000 ppm were used. Measurements of the heat source in the form of inlet and outlet temperatures, water productivity, and thermal efficiency are conducted for different flow rates of coolant and water feeds. The new arrangements are found to save much of the supplied heat, minimize the heat loss, and maximize the unit performance. An enhancement of 38.62% in the water productivity was achieved compared to the conventional AGMD unit. The considered heat recovery system showed water productivity of 155.92 m3/year for the proposed fresh potable water system with a cost of $12.85 per m3.

Addressing Water Age to Manage Legionella Pneumophila

<h3>Background</h3> A Minnesota Hospital established a Water Management Program (WMP) aligned with Centers for Medicare and Medicaid Services (CMS) and American National Standards Institute/American Society of Heating, Refrigerating and Air-Conditioning Engineers (ANSI/ASHRAE) Standard 188 with the goal to mitigate the risk of waterborne pathogen disease, namely Legionella pneumophila. Initial culture-based validation testing yielded positive Legionella results at distal locations including patient rooms in the potable water systems. Water quality monitoring confirmed low levels of free residual oxidant (FRO) disinfectant, leading to higher Legionella positives. This lower FRO was identified as a problem caused by high water age, defined by a long period of stagnation of water in the potable systems. To address the water age, the hospital's water management team (WMT) implemented a flushing program as part of ongoing verification and validation protocols. <h3>Methods</h3> Based on industry standards, the WMT focused on achieving a minimal control limit of 0.2 ppm (parts per million) of FRO to reduce water age on hot water systems. The WMT's solution included automated flushing on hot water returns, Environmental Services (EVS) personnel provided manpower for flushing at fixtures in patient areas based on low census and patient discharge. Validation testing confirmed the efficacy of the flushing program to reduce water age which in turn reduced Legionella growth. <h3>Results</h3> The flushing program was able to increase the average FRO level in the hot water systems < 0.05 ppm (2019) to >0.20 ppm (2021). The higher FRO levels contributed to the downward trend of 17% positive Legionella samples (2019) to 0% (2021) during Validation sampling. <h3>Conclusions</h3> Reducing water age by involving EVS in the WMT and implementing flushing procedures increased FRO levels system wide. Flushing was the simplest, safest, and most cost-effective solution compared to other solutions like supplemental disinfection while also reducing positive-detect Legionella samples.