Closing the Gap Between HBT Targets and CCP Assurance in Drinking Water

Closing the Gap Between HBTs and Day-to-Day Assurance

Health-based targets (HBTs) outline what has to be achieved for safe drinking water, but they do not, on their own, prove that a plant is actually hitting those outcomes every single day. That proof sits in how well we monitor, document, and control our critical control points (CCPs). This distinction is vital for Victorian utilities when conditions are shifting and regulators, boards, and communities are asking sharper questions about microbial log reduction performance.

Today we’ll unpack HBTs, explain why traditional validation and verification methods leave compliance gaps, and show how CCP assurance provides the operational bridge between design intent and what really happened on a random Tuesday afternoon.

Why Meeting HBTs on Paper Isn’t Enough

HBTs (health-based targets) are health outcome goals, expressed as log reduction requirements for viruses, bacteria, and protozoa. In the Australian Drinking Water Guidelines (ADWG), the treatment targets are linked to source water quality and risk assessments. The exact requirements depend on the source water category and the relevant ADWG tables.

Verification and validation are designed to answer the question, can this plant, set up this way, achieve those HBTs-linked log reductions? Through a mix of lab testing, challenge studies, and commissioning checks, we build evidence that the treatment train can hit the target under defined conditions. The tension appears later, when the plant has been running for months or years under changing water conditions, staffing levels, and asset states, and regulators or communities expect assurance that the same performance is still being delivered now.

This is particularly sharp in Victoria, where the expanded Safe Drinking Water Regulations (SDWR) 2025 include explicit expectations around how log reduction shortfalls are identified, assessed, and reported. When something goes wrong, it is not enough to point to an old validation folder. There is a growing expectation of transparent, defensible, time-specific evidence tying CCP control back to HBTs.

From Design Intent to Tuesday Afternoon Operations

Treatment plants start in a neat, structured way. Engineers classify the source water, assign required log reductions for each pathogen group, and select processes to provide those log reduction credits across multiple barriers. Commissioning then checks the pieces: filters can achieve their assigned turbidity and pathogen removal, disinfectants can meet required contact times and residuals, and the overall system, on paper and in tests, meets HBTs.

Real-world operation is much messier. Seasonal changes alter raw water turbidity and temperature. Assets age, media fouls, instruments drift, and sometimes workarounds creep in to keep water flowing during constrained periods. Staff turnover can mean doctrine is not always applied exactly as intended. Over time, confidence that the plant is still behaving like the verified version starts to erode, especially if incident reviews uncover gaps in monitoring or record-keeping.

This is where we need to separate capability from performance. Verification shows what the plant can do when everything is aligned. Ongoing operation has to show what the plant actually did at particular points in time. During audits, complaints, or incidents, the key questions become very specific: were CCPs in spec at this time, and if not, what was the likely impact on log reduction performance and HBTs compliance?

How CCP Assurance Secures Ongoing HBT Compliance

CCPs are treatment steps where effective control is essential for delivering HBT log reductions. Typical examples include filtration performance, disinfection contact time and residual, and membrane barrier integrity.

The logic chain is straightforward:

• CCPs are established and verified to deliver specific log reductions.
• If CCPs remain within their verified operating limits, the plant is operating as validated.
• If the plant is operating as validated, we have a defensible basis to claim that the required log reductions are being achieved.

CCP assurance is about being able to prove, over time, that each CCP stayed in control, that any exceptions were detected quickly, and that corrective actions were effective and documented. This turns CCP assurance into the operational bridge between high-level HBTs and the practical evidence you need when regulators, auditors, or internal leaders ask, were we actually meeting our treatment targets at this time?

Why Spreadsheets Struggle with CCP Reality

In theory, CCP monitoring could be as simple as checking if a value is above or below a limit. In reality, CCP rules are often layered and conditional. A single CCP may depend on:

• Multiple parameters, such as turbidity, disinfectant residual, and flow.
• Time factors, including contact times, delays, and persistence of alarms.
• Plant state, such as online, offline, bypassed, or operating in a special mode.
• Combinations of conditions, for example, different limits during start-up or shutdown.

Trying to capture all of this in manual checks or simple spreadsheets typically leads to one of two outcomes. Either the logic is oversimplified, which means subtle but important exceptions are missed, particularly during transitions and abnormal events. Or you build a complex spreadsheet that throws so many false alarms and data points at operators that it becomes noise, and real issues can be buried in the clutter.

The evidence burden is equally challenging. When an investigation or audit lands, someone has to reconstruct CCP histories from SCADA screenshots, paper logs, lab reports, and operator notes. This is slow, stressful, and prone to transcription errors. This is especially problematic when time-critical reporting is required under Victoria’s Safe Drinking Water Act Section 18 and Section 22 notifications. The more complicated the CCP logic, the harder it is to reliably and rapidly rebuild what actually happened.

Turning CCP Data Into Proof of Log Reduction

For operators, proof is not an abstract concept. It is specific, time-stamped information they can stand behind, even under questioning. In D2K Information’s work across the Australian water sector, we see CCP assurance working best when it delivers:

• Clear visual status of each CCP over time, showing within spec and out of spec periods.
• A consistent set of limits and rules directly traceable to the original validation or verification basis.
• Automatic logs of exceptions, including start and end times, cause where known, and corrective actions.
• Exportable reports aligned with internal needs and external reporting formats.

That is why we custom-designed the Information Engine™ software and the integrated CCPWatchⓇ module. The software is designed to pull data from existing SCADA and telemetry sensors, apply complex CCP rules consistently, highlight exceptions, and automatically build the associated logs and reports. The key point is that software does not create log reduction. What it does is make the CCP assurance story visible, repeatable, and audit-ready, so that meeting HBTs is supported by a clear ongoing record rather than a one-off validation exercise.

Information Engine™ and CCPWatchⓇ can be configured specifically for Victorian and national regulatory requirements. For example, if a disinfection CCP has a verified minimum residual and contact time to achieve a certain log reduction outcome, any period out of spec can be clearly identified, assessed for likely impact on log reduction, and documented. The software’s automated CCP assurance supports internal escalation. Therefore when a potential shortfall against HBTs treatment protocols is identified, the system record feeds into Section 18 or Section 22 notifications with far less manual effort.

Building Daily Confidence in Log Reduction Outcomes

Designing and verifying treatment to meet HBTs is only half the task. Real confidence comes from being able to show, for any day and any hour, that CCPs were within spec and that verified barriers were actually delivering the intended log reductions. This is what operators, regulators, and communities increasingly expect: not just targets, but proof.

We encourage organisations responsible for drinking water quality to look hard at their current CCP assurance approach. How clearly are CCP rules defined and linked to log reduction credits? How reliably are exceptions detected, managed, and recorded? How quickly could you assemble a defensible in-plant evidence trail if your HBTs performance was questioned tomorrow? By connecting HBTs, verification, and CCP assurance into one coherent system, utilities, health providers, and large facilities can move from reactive, paper-heavy responses to a more confident, data-backed account about drinking water safety every single day.

Strengthen Your Water Strategy With Consistent Visibility

If you are ready to move from high-level guidelines to practical, measurable outcomes, we can help you make your water network compliant with national HBTs (health-based targets). At D2K Information, we translate complex data into clear insights and network visibility, so you can prioritise investment, manage risk, and demonstrate consistent compliance. Contact us to talk about your specific challenges and we will shape a fit-for-purpose approach for your assets and stakeholders.