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European Journal of Applied Sciences – Vol. 10, No. 5

Publication Date: October 25, 2022

DOI:10.14738/aivp.105.13209. Gallant, R., Bloetscher, F., & Meeroff, D. E. (2022). Ongoing Issues in Water Distribution Systems and Solutions to Address Them.

European Journal of Applied Sciences, 10(5). 360-389.

Services for Science and Education – United Kingdom

Ongoing Issues in Water Distribution Systems and Solutions to

Address Them

Richard Gallant

Florida Atlantic University

Frederick Bloetscher

Florida Atlantic University

Daniel E. Meeroff

Florida Atlantic University

ABSTRACT

The goal of water utilities is to provide sufficient quantities of high quality water

that does not pose a public health concern to its customers. For the most part,

publicly owned water systems comply with all regulations on a consistent basis, but

the backlog of infrastructure needs means that longer term, compliance may be an

issue. Operational issues like biofilm management is particularly tricky for utilities

to deal with. The results herein indicate that biofilm formation potential can be

predicted with discriminant analysis and linear regression if sufficient data is

obtained. The correct data is important. The data also indicates that utilities at risk

for biofilms should include measures to reduce biofilms in their regularly

scheduled maintenance. In trying to address competing issues in a cost limited

environment can create internal conflicts, where implementing one solution

creates a new problem. The desire to save money can also compromise compliance

and endanger public health.

INTRODUCTION

Access to adequate, safe potable water supplies is a critical requirement for a stable society.

That is why governments have attempted to manage this critical resource for centuries

(Bloetscher, 2019). The managing and delivery of potable drinking water via pressurized,

underground piping systems is a more recent development, grounded in a better

understanding of disease outbreaks and the role water plays in transmitting illness. For over

150 years, improvements have been made to waterworks systems in an effort to reduce

waterborne disease outbreaks. For much of the developed world, western Europe and North

America, these efforts have been relatively successful since outbreaks of waterborne disease

are uncommon and tend to occur in groupings, as opposed to consistent outbreaks. In contrast,

the World Health Organization (WHO) reports that diseases associated with unsafe water

distribution, sanitation, and hygiene cause approximately 829,000 deaths per year worldwide

(WHO, 2019).

To protect public health in the US, Congress instructed the US Environmental Protection Agency

(USEPA) to establish National Primary Drinking Water Regulations (NPDWRs) that set

enforceable water quality standards for drinking water contaminants (USEPA, 1989, 2001,

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Gallant, R., Bloetscher, F., & Meeroff, D. E. (2022). Ongoing Issues in Water Distribution Systems and Solutions to Address Them. European Journal

of Applied Sciences, 10(5). 360-389.

URL: http://dx.doi.org/10.14738/aivp.105.13209

2002, 2004). These enforceable standards created “maximum contaminant levels” (MCLs),

which represent the maximum allowable concentration of a contaminant in drinking water.

There are over 90 regulated contaminants in drinking waters, including seven microorganisms,

including the pathogenic microorganisms Cryptosporidium, Giardia lamblia, Legionella and

enteric viruses. Several indicators of microbial risk and treatment system effectiveness,

including heterotrophic plate count, total coliforms, and turbidity are also monitored

(Bloetscher and Plummer 2011).

USEPA has also established National Secondary Drinking Water Regulations (NSDWRs) that set

non-mandatory water quality standards for 15 additional contaminants. These contaminants

are not considered to present a risk to human health, so there is no associated enforcement.

However, these secondary MCLs were established as guidelines to assist public water systems

in managing their drinking water for aesthetic considerations, such as taste, color, and odor

(USEPA, 2001).

To evaluate the effectiveness of the regulatory framework, the Centers for Disease Control

(CDC) and USEPA have maintained a collaborative surveillance system for collecting and

reporting waterborne disease outbreaks since 1971. From 1971 to 2008, Craun (2012) reports

there were 733 outbreaks reported in public water systems that resulted in 579,582 cases of

illness and 116 deaths. Note that over 400,000 of the cases and 62 of the deaths were associated

with one incident in 1993 – the City of Milwaukee. Post Milwaukee, for the period from 1997

to 2006, there were 137 waterborne disease outbreaks reported to the CDC, encompassing a

total of 8,498 illnesses and 17 deaths (Barwick et al., 2000; Blackburn et al., 2004; Liang et al.,

2006; Yoder et al., 2008). Of the outbreaks with a known cause from 1997-2006 (n = 101), 17

were attributed to chemical or toxin poisoning and 84 to pathogens. Nonspecific bacteria were

among the most commonly implicated pathogens. The highest number of outbreaks where the

culprit was known were due to Legionella, Giardia, Campylobacter, norovirus and E. coli

O157:H7 with 78% of outbreaks attributed to groundwater systems (Bloetscher and Plummer,

2011). Benedict et al (2017) report 110 waterborne disease outbreaks associated with

drinking water during the period 2009–2014. During the 2013-2014 survey period, a total of

42 outbreaks associated with drinking water were reported from 19 states, resulting in 1,006

cases of illness, 124 hospitalizations (12 percent of cases) and 13 deaths (Benedict et al 2017).

The majority of outbreaks (57 percent) and all of the deaths were due to Legionella (Benedict

et al 2017). During the 2009-2010 survey period, a total of 33 outbreaks associated with

drinking water were reported from 17 states, resulting in 1,040 cases of illness, 85

hospitalizations (8.2 percent of cases) and nine deaths (CDC 2013). The majority (58 percent)

of outbreaks were due to Legionella (CDC 2013).

While some of these outbreaks might be attributable to issues with water plant disruptions,

contaminated water can indicate an issue in the distribution system. Bacteria create biofilms in

the distribution system despite disinfection residuals. A chlorine residual is maintained in the

distribution system to disinfect the pipe and control biofilms, although some groundwater

systems may be exempted (Alamosa, CO did not chlorinate when they had their issues in 2008).

Therefore, tracking down water distribution issues is challenging.

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European Journal of Applied Sciences (EJAS) Vol. 10, Issue 5, October-2022

Services for Science and Education – United Kingdom

From a regulatory perspective, biofilm control is distribution controlled, but some recent

evidence suggests that operational issues at water plants, and the regulatory guidance given for

same, may actually encourage rather than prevent biofilm formation. Since biofilms are

recalcitrant, a means to detect biofilms based on water quality is proposed. However, the

enclosed case study comparing several existing treatment plant distribution systems provides

evidence that the plant operations may impact biofilm formation.

Biofilms In Water Distribution Systems

Microorganisms are the most widely distributed life forms on the planet (Chappelle, 2001).

Given that they thrive in the presence of moisture and nutrients, water distribution systems

can be optimal locations for growth on pipe walls in low flow conditions, where chlorine

residuals are low and other factors (Videla, 2018, Bloetscher et al. 2003, 2010). During biofilm

growth, the microorganisms excrete a matrix of extracellular polymeric substances (EPSs),

which lead to the formation of a slime layer that connects cells and anchors them to the surface

and to each other. The pathogenic pseudomonas sp. are among the slime formers commonly

found in biofilms (Bloetscher et al 2002a-d). These biofilms trap nutrients, and provide

resistance to velocity currents and disinfectants (Fleming and Wingender 2001; Videla, 2018;

Bloetscher et al. 2002a-d). From the utility perspective, uncontrolled biofilms can become a

considerable issue for water distribution systems, particularly with regard to maintenance

issues such as iron pipe damage (corrosion and tubercles), economic consequences (early pipe

failure/replacement and more frequent flushing of clean water), and public health issues such

as proliferation of pathogens.

A wide range of primary pathogens and opportunistic pathogens have demonstrated the ability

to survive and thrive in biofilms (see Table 1 –from Bloetscher et al., 2010). The release of

pathogens harbored in biofilms can lead to an increase in the incidence of gastrointestinal

symptoms. To wit, the Centers for Disease Control and Prevention (CDC) identified biofilms as

the source for 65% of human bacterial infections from community water supply associated

outbreaks (USEPA, 2008c). An important point to consider is that only coliforms are routinely

analyzed for in drinking water as mandated under the Total Coliform Rule (TCR) and the

Ground Water Rule of the Safe Drinking Water Act (SDWA), while these opportunistic

pathogens are not.

The steps in the life cycle of a biofilm include attachment, slime formation, growth, and

detachment or sloughing (Videla, 2018). Key requirements for biofilm development include an

active microbial community and interaction with pipe materials (Videla, 2018). The first

microorganisms to attach are called “pioneers,” which are most commonly facultative

anaerobes that excrete a mass of extracellular polysaccharides (EPSs). As the biofilm continues

to coat the pipe surface, acid-formers can reduce the pH near the pipe wall and accelerate

corrosion (Videla, 2018). A depleted oxygen layer forms in mature biofilms near the wall and

an anaerobic environment in which sulfate-reducing bacteria (SRB) proliferate because the

transport of oxygen into the anaerobic layer of the biofilm is limited by the biological activity in

the upper layers (Bloetscher et al., 2002a-d, Bloetscher et al 2010). Once mature colonies are

established, the effects of microbiologically induced corrosion (MIC) are often seen. A biofilm

can have all these effects because the heterotrophic biomass typically found in a biofilm

supports the synergistic effects of mixed growth rates, mixed metabolisms, and high surface