Water Workforce Toolbox Drinking Water

The Australian Drinking Water Guidelines (ADWG) provides a framework for the management t of drinking water quality that includes a comprehensive outline of the process of water supply system analysis. In summary:

The drinking water supply system is defined as everything from the point of collection of water to the consumer and can include:

catchments, including groundwater systems;

source waters;

storage reservoirs and intakes;

treatment systems;

service reservoirs and distribution systems;

consumers.

Drinking water systems are dynamic and water supply systems can change, for example.

Drought may result in loss (or reversal) of stream flows.
Elevated water temperatures resulting in higher biological activity and increased chlorine demand.
Higher temperatures may result in higher nutrient concentrations, leading to algae and cyanobacteria blooms.
Decreased reservoir volume can lead to higher salinity, higher DOC, higher turbidity, increased animal and bird activity around reservoirs resulting in higher erosion, E.coli, pathogens.
Decreased reservoir volume also leads to greater relative proportions from WWTP effluents in water sources, increased relative trace chemicals, possible temperature stratification and anoxic conditions.
Floods will result in erosion leading to higher sediment loads and TOC while damaged pumps and potentially submerged WWTPs will have impacts on source waters, potentially increased turbidity and colour (organic and inorganic), increased pathogens, nutrients, DOC.
Loss of vegetation from bushfires in a catchment results in higher erosion leading to sediment, OC and nutrient (P) mobilisation and damage to soils may result in slow recovery of vegetation and long-term impacts on source waters.
Ash and silt runoff leads to increased DOC, colour, turbidity, nutrients, metals: increased aerobic metabolic activity leads to lower DO.
Development of previously undeveloped land areas increased runoff, and potential for contaminants entering the waterway (hydrocarbons, metals).
Increased abstraction rates due to increased or new demands (drought/urban development) can expand the cone of depression of local groundwater, drawing water from more distant sources that have untested groundwater quality.

Case Study: Havelock North campylobacteriosis outbreak

In August 2016 a waterborne disease outbreak of gastroenteritis occurred in the town of Havelock North in the Hawkes Bay region of the North Island of New Zealand. Of the town’s 14,000 residents, 5500 were estimated to have become ill with campylobacteriosis, and 45 subsequently hospitalised. It is possible that the outbreak contributed to four deaths, and a number continue to suffer health complications.

Contaminated drinking water was the source of the outbreak with sheep faeces the likely source of the campylobacter. The root cause is likely to be heavy rain that inundated paddocks and caused contaminated water to flow into a pond about 90 metres from a supply bore. This water entered the aquifer from which the bore abstracts, and the well pump conveyed the contamination into the reticulation. Subsequent analysis of the catchment for the bore suggested that the clearing of trees in the vicinity of the pond disrupted the impermeable barrier at the top of the aquifer, permitting the free flow of contaminated water into the shallow aquifer. The land clearing had taken place several years prior to the event, but the unusually heavy rainfall caused the flushing of contaminated runoff water into pond and from there into the water system.

Queensland Health and qldwater recorded a panel discussion providing a first-hand account of the preconditions of this disaster and what could have been done differently.

Health Based Targets

HBTs are derived from quantitative definitions of microbial safety – pathogens are clearly recognised as the greatest risks to consumers and defining targets is an important risk management tool.

While there are different ways to approach setting targets, including HBTs to the ADWG are based on World Health Organisation and other international approaches.

Resources related to HBTs

A fact sheet produced by Water Research Australia which explains Disability-Adjusted Life Years (DALYs) – a way of measuring the population impact of a health problem.

The Water Services Association of Australia’s Manual for the Application of Health-Based Treatment Targets – as the title implies it is a practical guide to approaching risk assessments. Applying the risk assessment, which considers raw water supplies, determines the treatment barriers necessary for a drinking water system.

Harmful Algal Blooms

Why cyanobacteria blooms are bad for business

The warm conditions that makes Queensland so attractive to those living in colder climates unfortunately means that cyanobacteria blooms (otherwise known as Harmful Algal Blooms or HAB) appear in surface waters unusually early in the season, and in locations where they have historically been infrequent.

In 2023, qldwater hosted a series of webinars focused on three different aspects of HABs that are relevant to drinking water service providers.

Recordings of the webinars are available below:

Webinar 1: Bureau of Meteorology (BOM) climate and water outlook for the coming season

Thursday 20 October 2023, 10:00 – 11:00 am

by Matthew Coulton, General Manager Agriculture and Water at the Bureau of Meteorology

We have all seen a warmer than average winter and now, with both an El Niño and a positive Indian Ocean Dipole (IOD) underway, their combined impact can increase the chance of below average rainfall over much of Australia and higher temperatures across the southern two-thirds of the country. Based on history, it is now also more likely that warm and dry conditions will persist over eastern Australia. El Niño events also increase the risk of extreme temperature shifts like heatwaves, hotter days and increased fire risks. Matt provides a Climate and Water briefing for the 2023-24 summer.

Webinar 2: Managing HAB through your Drinking Water Quality Management Plan: Office of the Water Supply Regulator

Thursday 26 October 2023, 10:00 – 11:30 am

by Ted Aldred, Manager Water Supply Regulation – Water Operations and Systems, Department of Regional Development, Manufacturing and Water

Blue green algae outbreaks in surface waters can be challenging for water service providers, especially when coupled with other risks that are heightened by high temperatures. Boiling drinking water is not an effective means for removing or inactivating toxins associated with HABs. In this webinar Ted talks about the role of the Drinking Water Quality Management Plan in managing these risks to provide safe drinking water for your community.

Download the presentation

Download Management Strategies for Cyanobacteria (blue-green algae): a guide for water utilities

Webinar 3: Health Aspects of Harmful Algal Blooms

Thursday 2 November 2023, 10.00 to 11.00 am

by Dr Phil Choi, Senior Environmental Health Scientist, Queensland Public Health and Scientific Services, Queensland Health

The conditions that favour HABs include warm temperature, stratified water and calm or stagnant conditions: all circumstances that are associated with drier than usual wet seasons. If HABs do occur, they have the potential to impact drinking water supplies as well as recreational and irrigation water supplies. Queensland Health is currently updating its FAQ on HAB, and in this presentation Phil provides an overview of the different kinds of algae, the impact of location that leads to toxins forming, and how these impact on the health of people and animals.

Download the presentation

Other resources:

American Water Works Association Resources on Cyanobacteria/Cyanotoxins

US EPA Resources on Cyanobacterial Harmful Algal Blooms in Water Bodies

Webinar 4: Service provider experiences with HAB

Thursday 9 November 2023, 10.00 to 11.00 am

In this webinar we have presentations from water service providers with experience in management of harmful algal blooms reflecting on different mitigation strategies, what worked, what didn't and other lessons learned.

Tania Strixner-Harvey from Mount Isa Water Board presents on "Blue-green algae at Clear Water Lagoon: The journey so far…"

Trish Knavel and Laura Shiels from Townsville City Council presents "Managing Harmful Algal Blooms – Townsville City Council’s Experience"

Download the Townsville City Council presentation

Water Workforce Toolbox

Drinking Water Quality Management Plans

Water Service Providers complete DWQMPs and report these annually to the Department of Regional Development, Manufacting and Water.