Measuring Chlorine & Turbidity in Reticultation Systems or for Mains Breaks

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Twenty years ago in July-September 1998, Sydney experienced a Water Quality Crisis involving the suspected contamination by the pathogens, cryptosporidium and giardia in the water supply system.

Following the crisis, many stakeholders came together to develop a comprehensive response to minimise the chance of such an event happening again.  Some of the recommendations were an adoption of a Hazard At Critical Control Points (HACCP) concept to Water Quality, which was already operating successfully in the Pharmaceutical Industry. HACCP is now firmly established in the water industry and is driven by many passionate leaders to ensure customers’ safety remains paramount.  No one wants to see another repeat of 1998.

The basic concept of the HACCP is that Safety and Quality is likely to be far more effective when a Proactive Risk Management approach is taken rather than relying only on end-point testing when it may be too late to take impactful corrective action.

Risk to the Reticulation System

One area of the water cycle that benefits from this approach is the reticulation system where there is possibility of contamination of supply, either when a new mains line is being commissioned or in the event of a mains break.

In such situations even though the system will have been disinfected prior, the available chlorine residual may be insufficient to manage significant microbiological contamination and pose a risk to public health. To manage this risk adequate chlorine residuals must be maintained across the entire system. To accomplish this, on-site accurate chlorine residual measurement is vital.

Turbidity and Pathogens

Turbidity is also very important in reticulation system monitoring. Turbidity can have both water safety and aesthetic implications for drinking water supplies. Turbidity itself does not always represent a direct risk to public health, however, it can indicate the presence of pathogenic microorganisms, and be an effective indicator of hazardous events throughout the water supply system. Turbidity measurement can provide a quick check of microbial ingress which could be later confirmed by a sample taken to a Laboratory for pathogen analysis.

A Novel Instrument for Reticulation Monitoring

Hanna Instruments HI93414 combines Turbidity and Chlorine Residual measurements in one meter.  The optical system follows US EPA approved method, measuring Chlorine and Nephelometric Turbidity in the range required for potable water quality compliance.

Robust enough for field measurements this meter enables operators to meet the demands of a mains break or new main installation. Reagents and Standard Solutions are non-toxic, important in field testing. The HI93414 has data logging and GLP information which can be uploaded to a PC for traceability.

The real benefit to the operator is that instead of carrying around two meters, all can be accomplished in one compact meter.  When operators are investigating mains breaks, they will need to  measure both of these parameters to determine the source of the water, and several Australian Water boards have purchased this meter as an all-in-one solution for their maintenance vehicles.

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