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Australian Drinking Water Guidelines: Revised Chapter 5 Microbial Quality of Drinking Water incorporating a microbial health based target

Closed on Friday, 29 June 2018, 05:00pm (AEDT). Submissions are no longer being accepted.


The Australian Drinking Water Guidelines (ADWG) developed by the National Health and Medical Research Council (NHMRC) are designed to provide an authoritative reference to the Australian community and the water supply industry on what defines safe, good quality drinking water, how it can be achieved and how it can be assured. The ADWG undergo rolling revision to ensure they represent the latest and best available scientific evidence on good quality drinking water.

Over several years NHMRC has worked with stakeholders to strengthen advice on microbial quality of drinking water by developing advice on a quantitative microbial health based target (HBT).  This has included consulting stakeholders through discussion papers (2010 and 2014), a stakeholder workshop (2012) and a public consultation on a draft microbial HBT framework (2016). Based on stakeholder feedback a health based target of 10-6 DALYs per person per year is used and is consistent with the approach used by the World Health Organization.

Since the 2016 public consultation the Water Quality Advisory Committee (WQAC) has significantly revised the microbial HBT framework taking on board stakeholder feedback and incorporated this into Chapter 5 Microbial Quality of Drinking Water. WQAC have also developed an accompanying technical appendix aimed at environmental engineers and scientists.

Aim of consultation

The aim of this public consultation is to seek stakeholder feedback on a revised Chapter 5 and accompanying technical appendix on the new quantitative health based target approach to defining microbial quality of drinking water.

This new approach is consistent with international best practice and will provide a quantitative definition for microbiological safety of drinking water, using selected reference organisms that represent the major groups of pathogens (bacteria, viruses and protozoa) to provide a definition for a low level of acceptable risk. This will strengthen guidance to water utilities and regulators on the water treatment requirements needed to reduce microbial risk to an acceptable level.

WQAC has used the WHO Quantitative Microbial Risk Assessment framework to derive treatment targets based on source water category using the best available Australian evidence/data to determine the type and number of water treatments required to meet the microbial HBT.

The guidance on microbial quality consists of two documents, the revised Chapter 5 and an accompanying technical appendix.

Chapter 5 outlines approaches for assessing microbial risk from enteric pathogens in source water and categorising source water based on vulnerability assessments and microbial indicator assessments. The information has been strengthened to provide a clearer consideration of protected groundwater. It details treatment targets based on log reduction values to enable water utilities to meet the health based target. Sections on enteric and opportunistic pathogens, cyanobacteria and nuisance organisms have also been updated.

A technical appendix provides full details of how the treatment targets were derived. This is primarily aimed at environmental engineers and scientists with a high level of technical knowledge and an interest in gaining an in-depth knowledge of how the treatment targets were derived.

NHMRC Council has approved public consultation for the draft revised Chapter 5 and accompanying technical appendix. You are invited, under section 13(d) of the NHMRC Act 1992, to make a submission to NHMRC regarding the revised Chapter 5 and technical appendix.

Feedback from the public consultation will be addressed by WQAC in finalising the documents. Following this, approval from NHMRC Council will be sought for publication as part of the ADWG.


NHMRC is seeking responses to specific questions that relate to the draft revised Chapter 5 and technical appendix.

Out of Scope

Issues raised on other aspects of the ADWG or water quality are not within scope of this process and therefore will not be considered.

Consultation documents

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Consultation date

Please note the Timezone is AEDT.

Opening date: 
Monday, 30 April 2018 - 9:00am
Closing date: 
Friday, 29 June 2018 - 5:00pm
Please note that for some NHMRC consultations no extensions will be given. Where extensions are available you will need to contact the project officer using the contact details at the bottom of this page. However, in order for NHMRC to extend the date of a submission you will need to have created an account and started a submission.
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Page reviewed: 6 July, 2018