ISO 31000 notes the importance of understanding internal and external context on the risk management process. Similarly, contemporary water quality risk management frameworks include the need to understand the system from source to end point (what we refer to as S2E). We find that the ‘gold’ in risk assessments is in setting up your foundation properly – once you have a good understanding of your context, the risk assessment has much more power and you will get so much more out of it.

A fundamental part of setting your water quality risk foundation, is properly describing your system. So, what makes a good system description for the purposes of a water quality risk assessment? Take a look at our checklist below of some of the main features you will need to cover.

What does the Framework say?

The Framework for Management of Drinking Water Quality is a water quality management system, within the Australian Drinking Water Guidelines, that is based on ISO 9001 and HACCP (hazard analysis and critical control points).

Element 2 of the Framework covers assessment of the drinking water supply system and in particular:

• Water supply system analysis
• Assessment of water quality data
• Hazard identification and risk assessment.

The system analysis and water quality data assessment are two critical inputs to an effective risk assessment. The actions required for the water supply system analysis are:

• A 2.1.1: Assemble a team with appropriate knowledge and expertise.
• A 2.1.2: Construct a flow diagram of the water supply system from catchment to consumer.
• A 2.1.3: Assemble pertinent information and document key characteristics of the water supply system to be considered.
• A 2.1.4: Periodically review the water supply system analysis.

We’ve written previously about the importance of the flow diagram, now we’ll have a look at what constitutes an appropriate standard of duty for the requirements of Action 2.1.3.

What is Needed?

Analysis of the water supply system generally consists of a description of the following:

The relevance of each of these areas to the drinking water quality risk context-setting approach, is discussed in more detail in our checklist below.

• Population Served: It is a good idea to document the population served at a given point in time (usually last census). Also important from a risk perspective is to understand and document how population may fluctuate in holiday periods. ‘Normal’ operating and ‘peak’ operating conditions will impact on operational requirements including levels of service.
• Nature of Supply: It is useful to record the water products you are delivering including potable (e.g. drinking water to meet XYZ guidelines) and non-potable water, and the end uses of that water. Normally, the scope of the risk management approach will be for drinking water only however, non-potable water can impact on drinking water from a cross connection or end use perspective, and hence, it needs to be included for scope completeness.
• Water Source: The sources of raw water should be documented as this sets the ‘source’ part of the S2E water quality supply chain and helps you understand the catchment risks. Any supplies that are sourced from outside of the organisation’s jurisdiction should also be documented as these may involve contractual agreements with the supplier. See our article here for more detail.
• Water Storage (pre-treatment): This component of the water quality supply chain may take the form of a dam, a weir or other form of impoundment. Where a run of river supply is used, water storage may not be strictly applicable but it is useful to consider the river as a form of storage.
• WTP Treatment Processes: The treatment processes should be described from the start of the process train to the point of entry to the distribution system. We will often include the manufacturer’s information and any other water quality relevant information e.g. Pre-filtration (ABC Brand filter – 130 µm, 10 kL balancing tank (with AS/NZS 4020 compliance), Filtration (dual media), UV disinfection for primary disinfection (with manufacturer’s validation certificate) and chlorine (gas) dosing to achieve residual only.
• Distribution of Product: Once the water has left the plant, it is important to understand how it is kept in a fit for purpose condition, until it reaches the customer. A description should consider transport (pumped, gravity), how the water is protected from ingress (e.g. backflow measures, positive pressure), additional treatment (e.g. chlorine boosting), any point of use disinfection.
• Special Controls: Other issues which may impact on the scope of the risk approach include the quality of chemicals, materials etc used in the production and delivery of the product, manual verification sampling of water from the distribution network, overall and key hazard customer backflow prevention and other measures (including a current trade waste customer register), operation and maintenance of all infrastructure to prevent recontamination, operational conditions to help with water turnover and minimise stagnation.
• Other Parties: In some jurisdictions, there may be parties in the water quality supply chain and other parties who are able to access your network or provide other services such as recycled water. It’s important to understand who your water quality supply chain parties are, as they will all present sources of risk.

So, the next time you’re reviewing your water supply description, use our checklist above to help you move ‘beyond compliance to champion’, in your water quality risk assessments!

Need help? Risk Edge has a vast experience in undertaking and auditing water quality risk assessments. Learn more here.

BIO:

By Annette Davison, Director and Principal, Risk Edge Pty Ltd; Director and Chief Risk and Product Officer, D2K Information Pty Ltd

Director and Chief Risk and Product Officer, D2K Information Pty Ltd

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