Conference Papers | 2000 Conference Papers
ANALYSIS AND CRITICAL CONTROL POINTS FOR WATER SUPPLIES
Kevin Hellier Water
Melbourne Water Corporation
safety plans have incorporated Hazard Analysis Critical
Control Point (HACCP) principles for many years now
to control the risks of contamination. The main thrust
of HACCP systems is to understand the risks associated
with the process and start focussing process control
away from end-point testing and towards control of the
critical operations earlier in the process. The result
is production with higher quality assurance and greater
opportunity to correct non-conforming product.
paper describes how HACCP can be applied to public drinking
water supplies and demonstrates the way in which Melbourne
Water has developed HACCP. It outlines the approaches
taken to risk assessment and identification of Critical
Control Points and the integration of HACCP within water
HACCP, water supply, risk assessment, hazard
Hazard Analysis Critical Control Points (HACCP) is in
its infancy for the water industry but has provided
controls for the safety of foods for over three decades.
Developed by the World Health Organisation and adopted
internationally, it is the primary risk management system
for the food industry.
might HACCP be necessary for our current drinking water
systems, considering such sophisticated treatment technologies
recent years developed countries with conventional water
treatment systems have still experienced water-borne
disease outbreaks. The UK Department of Environment,
Transport and the Regions (1998) reported on 25 known
outbreaks of cryptosporidiosis associated with consumption
of public drinking water supplies in the UK since 1988.
1998, pathogen monitoring in the Sydney distribution
system detected some form of contamination. An industry-wide
lack of knowledge was manifested about the significance
of various pathogens and the lack of knowledge and control
of modern water supply systems. The importance of relying
on more than the treatment barrier to contamination
was emphasised in the final report of the Sydney Water
Inquiry by Peter McClellan QC (1998), in which it concluded:
"There is general agreement that the most effective
approach to keeping Cryptosporidium and Giardia from
a water supply is to adopt a multiple barrier approach."
in pathogen testing have outpaced the understanding
of their health significance leaving water authorities
and health regulators in a quandary. On this issue McClellan
(1998) stated, "It is clear that the developing science
has advanced beyond the capacity of the health authorities
to provide an effective response". Should there
be assigned numerical limits for pathogens, mandatory
testing or prescribed treatment systems?
based, process oriented management systems such as HACCP
are an alternative being investigated for inclusion
as part of the rolling revision of the Australian Drinking
Water Guidelines (NHMRC/ARMCANZ 1996).
issues above have added to the demand for water authorities
to give greater assurance to consumers and industries
of water safety. This has put more emphasis on risk
management, quality assurance and process control within
the Australian water industry.
THE HACCP PRINCIPLES The intention of a HACCP system
is to focus on preventing or controlling hazards early
in the process rather than relying mainly on end-point
testing for quality control.
HACCP Guidelines "Codex Alimentarius" (FAO/WHO 1996),
meaning food code, detail 5 preliminary steps and seven
principles for implementing HACCP. The preliminary steps
are to assemble a HACCP team, describe the product,
identify its intended use, construct a flow diagram
and confirm the flow diagram on-site.
seven principles are:
Conduct a hazard analysis.
the Critical Control Points (CCPs).
a system to monitor control of the CCP.
the corrective action to be taken when monitoring
indicates that a particular CCP is not under control.
procedures for verification to confirm that the HACCP
system is working effectively
documentation concerning all procedures and records
appropriate to these principles and their application.
Critical Control Point is "a step at which control
can be applied and is essential to prevent or eliminate
a food safety hazard or reduce it to an acceptable level.
The intent of the HACCP system is to focus control at
CCPs" (FAO/WHO 1996).
HACCP complements the principles of barriers to transmission
of pathogens outlined in the Australian Drinking Water
Guidelines (NHMRC/ARMCANZ 1996). The structured approach
of HACCP to analysing hazards (to food safety) provides
a means of assessing the existing barriers to contamination
and improving upon their operation.
application of HACCP within an organisation needs to
be well supported by management and management systems
(or "pre-requisite programs"). Management commitment
and the principles of continuous improvement, incorporating
auditing and management review, should support HACCP
particularly because it is necessary that the HACCP
system be continually updated whenever there are changes
in the raw products, equipment design, operations or
scientific knowledge on hazards. Consequently, quality
management systems in accordance with the international
standard ISO 9001 are important supports to HACCP.
CAN HACCP WORK FOR WATER?
Differences between the food and water industries
Although well established within the food industry there
are some important differences in the water industry
which need to be considered. The most obvious are:
the diverse range of possible water-borne hazards,
particularly from multi-use catchments
continuous nature of supply between raw water sources
facilities that are often monitored and operated remotely
via telemetry, and
large, complex distribution networks
HACCP Guidelines state: "It is important when applying
HACCP to be flexible where appropriate, given the context
of the application taking into account the nature and
the size of the operation." (FAO/WHO 1996).
diverse range of water-borne hazards can be assessed
individually or in some cases groups of microorganisms,
or chemicals can be assessed. For instance, groups of
bacterial pathogens transmitted by birds such as Campylobacter
and Salmonella spp. might be assessed together. As too
might bacteria that are known to regrow in distribution
systems. The protozoan hazards may be more specific
in their prevalence in the catchment and unique in their
resistance to disinfection, therefore warranting individual
analysis. It is essential that the HACCP team includes
representatives with the appropriate microbiological
and chemical expertise to make these assessments.
supply of water on a continuous basis from raw water
(untreated) to tap results in the problematic management
of any non-conforming product (ie. water deemed "unsafe").
The water is not precisely traced within the distribution
system, although water quality models coupled with advanced
flow monitoring systems are advancing rapidly. Therefore,
much of the management of water that has been improperly
treated or potentially contaminated relies on operational
experience and cannot be described prescriptively for
every circumstance. If water quality monitoring of treated
water provides evidence of contamination the information,
in some cases, is received too late for corrective action
prior to significant amounts being consumed. This makes
the need for preventive measures and corrective actions
early in the process even more important for water supply
food manufacturing plants are completely contained in
one factory location and it is relatively easy to validate
the process flow. Site specific hazards and HACCP plans
can be developed. However, for water systems multi-site
HACCP plans are needed (particularly for large urban
systems) and it is necessary to simplify the process
description to an extent that does not compromise the
identification of hazards. This is particularly so of
the distribution system where generic process flow diagrams
the critical control points may also benefit from some
generic representation if there are many similar CCPs
throughout the system. For example, at a disinfection
CCP the critical limits, monitoring, corrective actions
and verification systems might apply the same operational
systems for many other disinfection plants controlled
by the organisation. The systems and procedures for
any remote operations via telemetry are crucial elements
of the CCPs.
requires that "Prior to application of HACCP
to any sector of the food chain, that sector should
be operating according to the Codex General Principles
of Food Hygiene, the appropriate Codex Codes of Practice,
and appropriate food safety legislation" (FAO/WHO
1996). When translated to water this means that HACCP
should be applied to systems that already meet health-related
Developing Melbourne Water's HACCP Plan
The first step was to assemble a team with the appropriate
expertise in water systems (catchments, water treatment
etc.), microbiology, chemistry and local operations.
This produced a mix of disciplines and organisational
levels within the team. Representatives of the retail
water companies (which manage the local distribution
and reticulation systems) were included. The Melbourne
Water team members all received formal training in HACCP
prior to the workshops.
workshops were conducted with the team to systematically
proceed through the Codex Alimentarius HACCP principles
and preliminary steps and to produce the necessary information
for documenting the plan.
team leader presented a draft product description, intended
product use and process flow diagrams for the team members
to discuss. The comments received from the team and
informal consultation with the retail companies were
then considered in finalising these details. Responsibility
for confirming various components of the diagram in
the field was given to individual team members belonging
to field teams.
Melbourne Water system was separated into four discrete
major systems from catchment to retail company interface
point. This allowed the unique water quality risks associated
with each system to be examined but also allowed the
grouping of common elements such as pipelines and tanks
across the four systems.
analysis of hazards by the team built upon the risk
assessment work done previously by similar Melbourne
Water teams under the direction of engineering consultants.
At each process step the sources of risk to water quality
(eg. native animals) and the associated hazards (eg.
bacteria, viruses) were identified. Then the existing
control measures were identified at that process step
and the significance of the risk determined without
consideration of the downstream controls. A simple matrix
of likelihood and consequence with a range of 1 to 5
was used for assessing the risk.
risks determined to be significant were evaluated further
for Critical Control Points (CCPs) and other points
of downstream control using the decision tree in Codex
(see Figure 1 below). This is done starting at the upstream
end of the process (the catchments) and working downstream.
sub-teams then identified critical limits, monitoring
systems and corrective actions for each CCP. Some critical
limits could not be validated within the workshop setting
and required technical investigation prior to implementing
validation, record keeping and documentation systems
were addressed in part during the workshops. Most of
these issues were developed further after the workshops
during the documentation of the plan which was carried
out by the team leader (Melbourne Water's HACCP representative).
Where are the Critical Control Points?
Possibly the most problematic of the HACCP planning
steps is determining the Critical Control Points (CCPs).
Codex provides a decision tree to assist with a logical
procedure for this but the use of this decision tree
is not mandatory.
it appears that those establishing a HACCP plan for
the first time identify a large number of CCPs (ie.
over 10). When developing the Melbourne Water plan there
were initially 26 CCPs identified but it was soon realised
that many of the controls being dubbed CCPs didn't practically
work as CCPs. Therefore, some operations which were
initially specified CCPs were not designated CCPs in
cases where :
The risks were adequately managed with standard procedural
measures or "good manufacturing practice" which prevent
or reduce the hazards entering the water (eg. catchment
management procedures, reservoir security inspections,
managing sediments and stagnant zones during operation
the distribution system), or
downstream controls exist.
net result of this re-evaluation was that the CCPs for
the Melbourne Water system are at the treatment plants.
That is for Melbourne Water, at filtration, disinfection
and pH correction. For comparison with the food industry,
pasteurisation is a CCP for processing milk where temperature,
time and mixing are monitored to ensure pathogen destruction.
1 : The Codex Decision Tree
CCPs must have critical limits which are scientifically
validated wherever possible. The process must measure
parameters to determine deviations beyond the critical
limits at a rapid frequency that allows adjustments
to maintain control within the limits and corrective
actions before the product is consumed.
water treatment plants it is important to establish
critical limits that are practical for operating the
plants. Therefore, some parameters used to validate
the critical limits are not necessarily the same as
those monitored at the Critical Control Point.
example, in the case of disinfection with chlorine,
these limits are validated by the scientific literature
and guideline recommendations relating to the inactivation
of microorganisms with specific Ct values and chlorine
contact times. However, unless the control system is
calculating Ct values on a continuous basis for operators
to respond to it is not practical to set a Ct value
as the critical limit because the limit must trigger
a corrective action in time to manage the water downstream.
In such a case, a specific chlorine residual level at
the plant should be the practical limit which has been
calculated (or "validated") to achieve the required
The role of water quality monitoring
is a tool to assess hazards and establish control systems
that focus on prevention rather than relying mainly
on end-product testing." (FAO/WHO 1996).
quality monitoring within the distribution system should
be used primarily as a verification of the process control
of hazards upstream. Of course this does not remove
the need for response protocols and corrective actions
where guideline values are not met. However, it does
mean that monitoring programs should be designed to
give an optimal performance assessment of the Critical
instance, the use of heterotrophic plate counts will
give a more sensitive measure of disinfection performance
than coliforms. Also, infrequent pathogen monitoring
within the distribution system provides little value
in verifying the effectiveness of upstream barriers.
The information gained for understanding and managing
risk is greater from monitoring high risk source waters
for pathogens (and other indicators) and monitoring
other treatment plant indicators (eg. turbidity and
the identification of hazards, preventive measures,
associated risk and Critical Control Points, HACCP can
help optimise water quality monitoring programs.
APPLICATION WITHIN WATER SYSTEM OPERATIONS
will be little sustained commitment from water authorities
and individual employees to implement HACCP if there
are not real improvements evident to operations. Some
of the practical ways in which the initial implementation
of HACCP within Melbourne Water is bringing improvement
Correction to treatment plant alarm settings and improved
awareness of alarm functions
responsibilities for corrective actions
change control over treatment plant settings
over important documents (particularly operating procedures
and contingency plans)
performance indicators at CCPs
of procedures relating to significant water quality
risks (eg. procedures for notifications during chemical
spills in catchments and procedures for the isolation
and draining of tanks).
of the major benefits of developing the HACCP plan for
Melbourne Water is the coordination of many systems
related to process control into one management system.
includes catchment protection plans, transfer system
operation rules, treatment plant procedures, the incident
management system, water quality research and future
strategies, water quality monitoring programs, maintenance
programs, training programs, supply contracts (particularly
treatment chemicals) and customer feedback.
Operators must be able to demonstrate their competence
to fulfil the HACCP system requirements at Critical
Control Points and for other operational preventive
measures. This does not mean that operators need to
understand all the theory of the HACCP principles, but
they should at least have a general awareness of HACCP
as a system for managing product safety. They must also
understand of the significance to water quality of their
role within the whole process.
must also demonstrate that they carry out operating
procedures, monitoring, corrective actions, documentation
and record keeping in accordance with the HACCP plan.
Again, this does not mean that operators need be well
versed in the HACCP plan but the organisation must ensure
that what takes place in the field is consistent with
the plan. For the implementation of Melbourne Water's
plan the existing systems at CCPs were already well
established and the HACCP plan was able to provide a
logical framework of process control by documenting
or referencing these existing systems.
instructions and procedures should be documented and
available at the places of operation. It is sometimes
difficult to determine the level of detail required
for written instructions and which procedures require
documentation to support operator training. Basically,
the combination of operator competence and work instructions
should be able to adequately demonstrate operational
control. HACCP by its nature helps focus attention to
the significant risk areas and the CCPs, so at least
documentation, at whatever level of detail, can be directed
towards the priority areas.
Treatment plant monitoring controls
Where a treatment plant is a CCP, the monitoring must
provide for a clear and immediate response to any breach
of the critical limits. Therefore well managed control
settings and alarm settings are crucial. Response protocols
for alarms including clearly defined responsibilities
should be incorporated in the HACCP plan and reference
should be made to contingency plans for managing the
inadequately treated water downstream of the plant.
corrective action will take two forms: that required
to bring the process back in control - ie. bringing
the plant back into correct operation and that required
to manage the water downstream of the plant. The former
is practically the responsibility of a competent operator
on duty but this operator is normally not in a position
to manage the water downstream. Therefore others in
the organisation are usually deployed for this latter
issue, which will often need the coordination of other
authorities, and in the worst cases the health department
for managing the public if unsafe water is likely to
reach consumers. The responsibilities, chain of command,
notifications, resources etc. for these actions should
be clearly identified.
The frequency of verification is to be designed to allow
determination of whether the HACCP system is working
correctly. This involves routine operational checks,
record reviews, internal auditing and performance reporting
of finished water quality monitoring. HACCP records
must be checked including confirmation that CCPs are
kept under control. At water treatment plants this means
Regular (eg. daily) review of plant performance and
equipment status on SCADA or controllers
plant operation checklists
checks on measuring equipment (eg. chlorine or turbidity
checks of water quality from treated water downstream
of any critical limit deviations and corrective actions
must also be reviewed. (Melbourne Water's pre-existing
emergency response system covered these events and specifies
responsibilities for log keeping, reporting and recording
follow up actions).
Auditing should be scheduled to cover all the CCP sites
and pre-requisite programs (such as incident management,
calibration etc.) over a reasonable period.
The experience of Melbourne Water's application of HACCP
has demonstrated how water authorities can successfully
adopt HACCP and overcome the aspects of water supply
systems that differ from the food industry. HACCP can
enhance the Multiple Barrier Approach to contamination
through its systematic analysis of hazards and the points
of control. It then ensures a rigorous control system
at the Critical Control Points and this Critical Control
Point concept applies well to water treatment plants.
as a process control oriented management system, can
therefore help water authorities to coordinate the functions
of their various water quality management systems to
provide assurance of a safe product.
Codex Alimentarius Commission (1996) "Report of the
Twenty-Ninth Session of the Codex Committee on Food
Hygiene" (ALINORM 97/13A).
Department of the Environment, Transport and the Regions
(1998) "Cryptosporidium in Water Supplies" Report of
the Group of Experts on Cryptosporidium in Water Supplies
chaired by Prof. Ian Bouchier.
(1996) "Australian Drinking Water Guidelines"
P. (1998) "Sydney Water Inquiry - Final Report" NSW