Dead-end flushing of a distribution system: Short and long-term effects on water quality

Barbeau, Benoît; Julienne, Karine; Carrière, Annie; Gauthier, Vincent

doi:10.2166/aqua.2005.0035

Cited by 42 publications

(35 citation statements)

References 11 publications

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“…Sediment formation is the result of particle deposition under favorable hydraulic conditions ( Vreeburg et al, 2008 ) ( Figure 3 ), and distribution networks can contains as much as 3000 mg/m loose deposits ( Barbeau et al, 2005 ; Vreeburg et al, 2008 ). Deposited particles offer a favorable environment for bacterial growth, as (i) they provide a large surface area, (ii) are usually composed of organic compounds and also (iii) contain inorganic substrates (e.g., Ca, Fe, Mn; Gauthier et al, 1999 ; Zacheus et al, 2001 ).…”

Section: A Deeper Look Into Microbial Dynamics In Drinking Watermentioning

confidence: 99%

“…and Geobacter sp., or bacteria from actinomycetes group; Zacheus et al, 2001 ; Liu et al, 2014 ). Sediments were shown to contain large amounts of biomass, in the range of 700 to 4000 ng ATP/g loose deposit ( Liu et al, 2014 ) and up to 10 11 cells/g ( Barbeau et al, 2005 ) and to harbor the largest bacterial diversity, compared to bulk water and biofilm phases, with 29% of the total bacteria which were not shared with the bulk water ( Liu et al, 2014 ). Sediments can be the source of hygienic and operational problems, as they offer a protective environment for bacteria to grow, particularly for undesirable organisms ( Gauthier et al, 1999 ), and iron-oxidizing bacteria shown to increase corrosion processes ( Sun et al, 2014 ).…”

Section: A Deeper Look Into Microbial Dynamics In Drinking Watermentioning

confidence: 99%

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Biological Stability of Drinking Water: Controlling Factors, Methods, and Challenges

et al. 2016

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Biological stability of drinking water refers to the concept of providing consumers with drinking water of same microbial quality at the tap as produced at the water treatment facility. However, uncontrolled growth of bacteria can occur during distribution in water mains and premise plumbing, and can lead to hygienic (e.g., development of opportunistic pathogens), aesthetic (e.g., deterioration of taste, odor, color) or operational (e.g., fouling or biocorrosion of pipes) problems. Drinking water contains diverse microorganisms competing for limited available nutrients for growth. Bacterial growth and interactions are regulated by factors, such as (i) type and concentration of available organic and inorganic nutrients, (ii) type and concentration of residual disinfectant, (iii) presence of predators, such as protozoa and invertebrates, (iv) environmental conditions, such as water temperature, and (v) spatial location of microorganisms (bulk water, sediment, or biofilm). Water treatment and distribution conditions in water mains and premise plumbing affect each of these factors and shape bacterial community characteristics (abundance, composition, viability) in distribution systems. Improved understanding of bacterial interactions in distribution systems and of environmental conditions impact is needed for better control of bacterial communities during drinking water production and distribution. This article reviews (i) existing knowledge on biological stability controlling factors and (ii) how these factors are affected by drinking water production and distribution conditions. In addition, (iii) the concept of biological stability is discussed in light of experience with well-established and new analytical methods, enabling high throughput analysis and in-depth characterization of bacterial communities in drinking water. We discussed, how knowledge gained from novel techniques will improve design and monitoring of water treatment and distribution systems in order to maintain good drinking water microbial quality up to consumer’s tap. A new definition and methodological approach for biological stability is proposed.

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Section: A Deeper Look Into Microbial Dynamics In Drinking Watermentioning

confidence: 99%

Section: A Deeper Look Into Microbial Dynamics In Drinking Watermentioning

confidence: 99%

Biological Stability of Drinking Water: Controlling Factors, Methods, and Challenges

et al. 2016

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“…A flushing program was completed in the temporary DMAs before implementation. However, it has been shown that the removal of sediments (mostly composed of iron, organic matter, and manganese) by spot flushing in dead ends produced short‐term impacts in the aesthetic characteristics of the water (Barbeau et al 2005). Moreover, studies investigating historical data of DMAs in the United Kingdom concluded that DMAs could influence discoloration (Armand et al 2015) as well as significantly higher customer complaints during summer when water consumption and water temperatures increase (Prasad & Danso‐Amoako 2014).…”

Section: Discussionmentioning

confidence: 99%

Predicting Water Quality Impact After District Metered Area Implementation in a Full‐Scale Drinking Water Distribution System

Dias

Besner²,

Prévost

2017

Journal AWWA

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Pressure management using district metered areas (DMAs) can reduce leakage and break frequencies and extend the service life of pipes in drinking water networks. Valves must be closed, creating DMAs, resulting in hydraulic changes and increasing the number of dead ends. A field study of five pilot DMAs was conducted using an enhanced sampling program. Water quality was measured at different locations inside and outside DMA boundaries before and after implementation. Overall water quality did not change following DMA implementation. However, water quality (chlorine residuals, turbidity, and metals) was degraded at locations with elevated water residence times such as created dead ends, sites outside DMA boundaries, and extremities. An approach based on the combination of hydraulic modeling and water quality was developed to predict trihalomethane concentrations in the DMA using measurements only from an inlet site. Utilities can use a combination of hydraulic modeling and targeted monitoring to predict water quality changes after DMA implementation.

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“…The failure to precede the development of the O&M schedule with identification of systemspecific risks led to the omission of some crucial tasks. For instance, the presence of dead ends in the distribution network required the inclusion of tasks such as spot flushing [25] or unidirectional flushing [26,27] to control biofilm and sediment accumulation at the dead ends. However, no specific tasks were included in the maintenance schedule to manage these risks.…”

Section: Water Safety Control Measures Against Hazards and Risksmentioning

confidence: 99%

Water Safety Planning and Implementation in a Ghanaian Small-scale Water Supply System

Obeng

Awere

2020

IJECC

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This study looked at the Assin Fosu Small Town Water Supply System in Ghana to verify whether the operation of the scheme is based on a comprehensive water safety plan and how the practice of water safety planning affects the quality of water delivered to the consumers. The study employed document reviews, structured observations, interviews and laboratory analysis of water samples. System design data files and an Operation and Management Contract document were reviewed along with in-depth interviews with key stakeholders of the water supply system. Structured observations were made to assess the management practices of the system managers. Three rounds of sampling of water were done at monthly intervals from 10 randomly selected public standpipes, 3 boreholes and 2 filtration units. Samples were analysed to assess their bacteriological safety and aesthetic (physical) quality (turbidity and colour). Upon detection of bacteriological contamination, the adequacy of disinfection was assessed by measuring the levels of residual chlorine. It was found that the recommended schedule for some key documented water quality control and monitoring activities were not complied with. Consequently, the quality of water delivered to consumers at several public standpipes failed to meet the WHO guidelines for drinking water. Forty percent (40%) of all samples were found with faecal contamination, with 60% and 50% exceeding the WHO’s guideline levels for turbidity and colour respectively. It is recommended that the Community Water and Sanitation Agency in Ghana intensifies on-going efforts at ensuring that small-scale water supply systems in the country are managed with comprehensive water safety plans to prevent microbial contamination which could pose significant health risks to the consumers.

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Dead-end flushing of a distribution system: Short and long-term effects on water quality

Cited by 42 publications

References 11 publications

Biological Stability of Drinking Water: Controlling Factors, Methods, and Challenges

Biological Stability of Drinking Water: Controlling Factors, Methods, and Challenges

Predicting Water Quality Impact After District Metered Area Implementation in a Full‐Scale Drinking Water Distribution System

Water Safety Planning and Implementation in a Ghanaian Small-scale Water Supply System

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