Potential microbial risks and their control in residential secondary water supply systems in China: a review

Abstract

Secondary water supply systems (SWSSs) are pivotal in urban water management. Municipal water entering SWSS storage tank undergoes hydraulic stagnation before being distributed to end users. This stagnation provides a stable microenvironment, facilitating a series of chemical reactions, particularly chlorine disinfectant decay resulting in favorable conditions for microbial proliferation. Elevated microbial loads within SWSSs directly compromise the microbiological safety of residential drinking water. In this review, we compile the findings from our studies and existing literature and systematically evaluate the latent microbial hazards in SWSSs serving both urban residential neighborhoods and self-built houses. SWSSs function as persistent reservoirs for pathogenic microbiota. We propose Legionella spp. as targeted supplementary microbiological indicators for routine water-quality monitoring in SWSSs. To mitigate the risks, we advocate implementing three-tiered interventions: 1) an optimized building layout and operation mode, 2) engineered secondary disinfection strategies, and 3) enhanced regulatory oversight through smart monitoring frameworks. In summary, we characterize the microbial contamination mechanisms in urban SWSSs and establish a vital scientific basis for advancing operational management and safety assurance.

Graphical abstract

Keywords

Secondary water supply systems / Water stagnation / Water quality / Chlorine decay / Microbial risks

Highlight

	● The SWSSs will experience deterioration of water quality.
	● SWSSs could promote the microbial regrowth and colonization of pathogens.
	● Legionella might be used as supplementary indicator of microbial risk in SWSSs.
	● Effective regulation and maintenance can reduce microbial risk in SWSSs.

References

[1] Adl S M, Bass D, Lane C E, Lukeš J, Schoch C L, Smirnov A, Agatha S, Berney C, Brown M W, Burki F. . (2019). Revisions to the classification, nomenclature, and diversity of eukaryotes. Journal of Eukaryotic Microbiology, 66(1): 4–119

[2] Al-Bahry S N, Elshafie A E, Victor R, Mahmoud I Y, Al-Hinai J A. (2011). Opportunistic pathogens relative to physicochemical factors in water storage tanks. Journal of Water and Health, 9(2): 382–393

[3] Al-Jasser A O. (2007). Chlorine decay in drinking-water transmission and distribution systems: pipe service age effect. Water Research, 41(2): 387–396

[4] Al-Omari A, Fayyad M, Jamrah A. (2008). Drinking water quality in roof storage tanks in the city of Amman, Jordan. Water International, 33(2): 189–201

[5] Alleron L, Khemiri A, Koubar M, Lacombe C, Coquet L, Cosette P, Jouenne T, Frere J. (2013). VBNC Legionella pneumophila cells are still able to produce virulence proteins. Water Research, 47(17): 6606–6617

[6] Babič N M, Gunde-Cimerman N. (2021). Water-transmitted fungi are involved in degradation of concrete drinking water storage tanks. Microorganisms, 9(1): 160

[7] Bodet C, Sahr T, Dupuy M, Buchrieser C, Héchard Y. (2012). Legionella pneumophila transcriptional response to chlorine treatment. Water Research, 46(3): 808–816

[8] Brown D, Bridgeman J, West J R. (2011). Predicting chlorine decay and THM formation in water supply systems. Reviews in Environmental Science and Biotechnology, 10(1): 79–99

[9] Brown D, West J R, Courtis B J, Bridgeman J. (2010). Modelling THMs in water treatment and distribution systems. Water Management, 163(4): 165–174

[10] Buse H Y, Morris B J, Struewing I T, Szabo J G. (2019). Chlorine and monochloramine disinfection of Legionella pneumophila colonizing copper and polyvinyl chloride drinking water biofilms. Applied and Environmental Microbiology, 85(7): e02956–18

[11] Cai X, Hu Y, Zhou S, Meng D, Xia S, Wang H. (2023). Unraveling bacterial and eukaryotic communities in secondary water supply systems: dynamics, assembly, and health implications. Water Research, 245(15): 120597

[12] Chandy J P, Angles M L. (2001). Determination of nutrients limiting biofilm formation and the subsequent impact on disinfectant decay. Water Research, 35(11): 2677–2682

[13] Deborde M, Von Gunten U. (2008). Reactions of chlorine with inorganic and organic compounds during water treatment—Kinetics and mechanisms: a critical review. Water Research, 42(1−2): 13–51

[14] Dietersdorfer E, Cervero-Aragó S, Sommer R, Kirschner A K, Walochnik J. (2016). Optimized methods for Legionella pneumophila release from its Acanthamoeba hosts. BMC Microbiology, 16(1): 74

[15] Dietersdorfer E, Kirschner A, Schrammel B, Ohradanova-Repic A, Stockinger H, Sommer R, Walochnik J, Cervero-Arago S. (2018). Starved viable but non-culturable (VBNC) Legionella strains can infect and replicate in amoebae and human macrophages. Water Research, 141: 428–438

[16] Digiano F A, Zhang W. (2005). Pipe section reactor to evaluate chlorine–wall reaction. Journal-American Water Works Association, 97(1): 74–85

[17] Dupuy M, Mazoua S, Berne F, Bodet C, Garrec N, Herbelin P, Ménard-Szczebara F, Oberti S, Rodier M H, Soreau S. . (2011). Efficiency of water disinfectants against Legionella pneumophila and Acanthamoeba. Water Research, 45(3): 1087–1094

[18] Evison L, Sunna N. (2001). Microbial regrowth in household water storage tanks. Journal-American Water Works Association, 93(9): 85–94

[19] Flemming H C, Van Hullebusch E D, Little B J, Neu T R, Nielsen P H, Seviour T, Stoodley P, Wingender J, Wuertz S. (2025). Microbial extracellular polymeric substances in the environment, technology and medicine. Nature Reviews. Microbiology, 23(2): 87–105

[20] García-Ávila F, Sánchez-Alvarracín C, Cadme-Galabay M, Conchado-Martínez J, García-Mera G, Zhindón-Arévalo C. (2020). Relationship between chlorine decay and temperature in the drinking water. MethodsX, 7: 101002

[21] Geng B, Fan J, Shi M, Zhang S, Li J. (2022). Control of maximum water age based on total chlorine decay in secondary water supply system. Chemosphere, 287: 132198

[22] Hallam N B, West J R, Forster C F, Powell J C, Spencer I. (2002). The decay of chlorine associated with the pipe wall in water distribution systems. Water Research, 36(14): 3479–3488

[23] He Z, Wang L, Ge Y, Zhang S, Tian Y, Yang X, Shu L. (2021). Both viable and inactivated amoeba spores protect their intracellular bacteria from drinking water disinfection. Journal of Hazardous Materials, 417: 126006

[24] Herson D S, Mcgonigle B, Payer M A, Baker K H. (1987). Attachment as a factor in the protection of Enterobacter cloacae from chlorination. Applied and Environmental Microbiology, 53(5): 1178–1180

[25] Hu D, Hong H R, Rong B, Wei Y T, Zeng J, Zhu J, Bai L J, Guo F, Yu X. (2021). A comprehensive investigation of the microbial risk of secondary water supply systems in residential neighborhoods in a large city. Water Research, 205: 117690

[26] Hu D, Li X, Zeng J, Xiao X, Zhao W, Zhang J, Yu X. (2023a). Hidden risks: simulated leakage of domestic sewage to secondary water supply systems poses serious microbiological risks. Water Research, 244: 120529

[27] Hu D, Lin W, Zeng J, Zhang H, Wei Y, Yu X. (2023b). To close or open the tank input water valve: secondary water-supply systems with double tanks will induce a higher microbial risk. Science of the Total Environment, 874: 162301

[28] Hu D, Zeng J, Chen J, Lin W, Xiao X, Feng M, Yu X. (2023c). Microbiological quality of roof tank water in an urban village in southeastern China. Journal of Environmental Sciences, 125: 148–159

[29] Hu D, Zeng J, Hu Y, Fei X, Xiao X, Feng M, Yu X. (2022). A survey on heavy metal concentrations in residential neighborhoods: the influence of secondary water supply systems. Journal of Environmental Sciences, 117: 37–45

[30] Huang C, Shen Y, Smith R L, Dong S, Nguyen T H. (2020). Effect of disinfectant residuals on infection risks from Legionella pneumophila released by biofilms grown under simulated premise plumbing conditions. Environment International, 137: 105561

[31] Lechevallier M W, Evans T M, Seidler R J. (1981). Effect of turbidity on chlorination efficiency and bacterial persistence in drinking water. Applied and Environmental Microbiology, 42(1): 159–167

[32] Ley C, Proctor C, Singh G, Ra K, Noh Y, Odimayomi T, Salehi M, Julien R, Mitchell J, Nejadhashemi A P. . (2020). Drinking water microbiology in a water-efficient building: stagnation, seasonality, and physiochemical effects on opportunistic pathogen and total bacteria proliferation. Environmental Science. Water Research & Technology, 6(10): 2902–2913

[33] Li H, Li S, Tang W, Yang Y, Zhao J F, Xia S Q, Zhang W X, Wang H. (2018a). Influence of secondary water supply systems on microbial community structure and opportunistic pathogen gene markers. Water Research, 136: 160–168

[34] Li M K, Qiang Z M, Bolton J R, Li W T, Chen P. (2014). UV disinfection of secondary water supply: online monitoring with micro-fluorescent silica detectors. Chemical Engineering Journal, 255: 165–170

[35] Li W T, Li M K, Wen D, Qiang Z M. (2018b). Development of economical-running strategy for multi-lamp UV disinfection reactors in secondary water supply systems with computational fluid dynamics simulations. Chemical Engineering Journal, 343: 317–323

[36] Ling F, Whitaker R, Lechevallier M W, Liu W T. (2018). Drinking water microbiome assembly induced by water stagnation. ISME Journal, 12(6): 1520–1531

[37] Liu G, Verberk J Q, Van Dijk J C. (2013). Bacteriology of drinking water distribution systems: an integral and multidimensional review. Applied Microbiology and Biotechnology, 97(21): 9265–9276

[38] Liu H, Wahman D G, Pressman J G. (2019). Evaluation of monochloramine and free chlorine penetration in a drinking water storage tank sediment using microelectrodes. Environmental Science & Technology, 53(16): 9352–9360

[39] Lu J, Struewing I, Yelton S, Ashbolt N. (2015). Molecular survey of occurrence and quantity of Legionella spp., Mycobacterium spp., Pseudomonas aeruginosa and amoeba hosts in municipal drinking water storage tank sediments. Journal of Applied Microbiology, 119(1): 278–288

[40] Ministry of Housing and Urban-Rural Development , People’s Republic of China (2010). CJJ140–2010 Standard for Technical Specification for Secondary Water Supply Engineering. Beijing: Ministry of Housing and Urban-Rural Developmentof China

[41] Miyagi K, Sano K, Hirai I. (2017). Sanitary evaluation of domestic water supply facilities with storage tanks and detection of Aeromonas, enteric and related bacteria in domestic water facilities in Okinawa Prefecture of Japan. Water Research, 119: 171–177

[42] Nakanishi T, Hirose M, Asada Y, Itoh S. (2024). Legionella community dynamics in a drinking water distribution system: impact of residual chlorine depletion. Science of the Total Environment, 956: 177302

[43] Napoli C, Fasano F, Iatta R, Barbuti G, Cuna T, Montagna M T. (2010). Legionella spp. and legionellosis in southeastern Italy: disease epidemiology and environmental surveillance in community and health care facilities. BMC Public Health, 10(1): 660

[44] Nordblom O, Bergdahl L. (2004). Initiation of stagnation in drinking water storage tanks. Journal of Hydraulic Engineering, 130(1): 49–57

[45] Powell J C, Hallam N B, West J R, Forster C F, Simms J. (2000a). Factors which control bulk chlorine decay rates. Water Research, 34(1): 117–126

[46] Powell J C, West J R, Hallam N B, Forster C F, Simms J. (2000b). Performance of various kinetic models for chlorine decay. Journal of Water Resources Planning and Management, 126(1): 13–20

[47] Qin K, Struewing I, Domingo J S, Lytle D, Lu J. (2017). Opportunistic pathogens and microbial communities and their associations with sediment physical parameters in drinking water storage tank sediments. Pathogens, 6(4): 54

[48] Schafer C A, Mihelcic J R. (2012). Effect of storage tank material and maintenance on household water quality. Journal-American Water Works Association, 104(9): 521–529

[49] Shen Y, Huang C, Lin J, Wu W, Ashbolt N J, Liu W T, Nguyen T H. (2017). Effect of disinfectant exposure on Legionella pneumophila associated with simulated drinking water biofilms: release, inactivation, and infectivity. Environmental Science & Technology, 51(4): 2087–2095

[50] Stout J E, Muder R R, Mietzner S, Wagener M M, Perri M B, Deroos K, Goodrich D, Arnold W, Williamson T, Ruark O. . (2007). Role of environmental surveillance in determining the risk of hospital-acquired Legionellosis: a national surveillance study with clinical correlations. Infection Control and Hospital Epidemiology, 28(7): 818–824

[51] Vasconcelos J, Rossman L, Grayman W, Boulos P, Clark R. (1997). Kinetics of chlorine decay. Journal-American Water Works Association, 89(7): 54–65

[52] Vieira P, Coelho S T, Loureiro D. (2004). Accounting for the influence of initial chlorine concentration, TOC, iron and temperature when modelling chlorine decay in water supply. Journal of Water Supply: Research & Technology-Aqua, 53(7): 453–467

[53] Vreeburg J H G, Boxall J B. (2007). Discolouration in potable water distribution systems: a review. Water Research, 41(3): 519–529

[54] Vreeburg J H G, Schippers D, Verberk J Q J C, Van Dijk J C. (2008). Impact of particles on sediment accumulation in a drinking water distribution system. Water Research, 42(16): 4233–4242

[55] Wan K Y, Jékely G. (2021). Origins of eukaryotic excitability. Philosophical Transactions of the Royal Society B, 376(1820): 20190758

[56] Wang J, Deng B, Jiang S, Deng Z, Wang W, Chen G, Liu L. (2024). Optimizing control of secondary water supply tanks for demand peak staggering. Water Resources Management, 38(11): 4123–4136

[57] Wang J, Sui M, Yuan B, Li H, Lu H. (2019a). Inactivation of two Mycobacteria by free chlorine: effectiveness, influencing factors, and mechanisms. Science of the Total Environment, 648: 271–284

[58] WangY, Liu M K, MiaoX C, WangY, BaiX H (2019b). Effect of urban water supply system on fungi population and community structure. Microbiology China, 46(01): 20–28 (in Chinese)

[59] Water Supply (Network) Department, Singapore (2022). Handbook on application for water supply. English revision.

[60] WHO (2017). Guidelines for Drinking-Water Quality: Fourth Edition Incorporating First Addendum. Geneva: World Health Organization

[61] Zahran S, Mcelmurry S P, Kilgore P E, Mushinski D, Press J, Love N G, Sadler R C, Swanson M S. (2018). Assessment of the Legionnaires’ disease outbreak in Flint, Michigan. Proceedings of the National Academy of Sciences of the United States of America, 115(8): E1730–E1739

[62] Zhang C, Li C, Zheng X, Zhao J, He G, Zhang T. (2017). Effect of pipe materials on chlorine decay, trihalomethanes formation, and bacterial communities in pilot-scale water distribution systems. International Journal of Environmental Science and Technology, 14(1): 85–94

[63] Zhang C, Struewing I, Mistry J H, Wahman D G, Pressman J, Lu J. (2021a). Legionella and other opportunistic pathogens in full-scale chloraminated municipal drinking water distribution systems. Water Research, 205: 117571

[64] Zhang C Q, Lu J R. (2021). Legionella: a promising supplementary indicator of microbial drinking water quality in municipal engineered water systems. Frontiers in Environmental Science, 9(386): 684319

[65] Zhang H H, Xu L, Huang T L, Yan M M, Liu K W, Miao Y, He H Y, Li S L, Sekar R. (2021b). Combined effects of seasonality and stagnation on tap water quality: changes in chemical parameters, metabolic activity and co-existence in bacterial community. Journal of Hazardous Materials, 403: 124018

[66] Zhang Y, Edwards M. (2009). Accelerated chloramine decay and microbial growth by nitrification in premise plumbing. Journal-American Water Works Association, 101(11): 51–62

RIGHTS & PERMISSIONS

Higher Education Press 2025