There is growing concern that micro-pollutants in water, even in small doses, threaten human and environmental health. Currently, the European Union is proposing a 50% increase in the number of substances that are monitored and controlled in surface waters – a move projected to cost utilities billions of euros in treatment and monitoring upgrades.

Closer to home, Australia is beginning to acknowledge and address micro-pollutant issues, said CH2M’s Regional Technology Manager for the Asia Pacific Region John Poon.

The Australian Drinking Water Guidelines (2011) (ADWG) outline a general approach to setting limits for inorganic chemicals, organic chemicals and pesticides, and there are specific guides for hundreds of individual chemicals outlined in factsheets. But as the Cooperative Research Centre for Water Quality and Treatment (CRCWQT) noted: “The ADWG includes numerical guideline values for relatively few chemicals.”

A compulsory full review of the guidelines occurs only every 10 years, but can be recommended after five by the National Health and Medical Research Council (NHMRC).

The council said it used a variety of mechanisms to keep abreast of emerging issues. prioritising them based on potential human health impact and stakeholder concern.

“There are a number of formal mechanisms that exist for jurisdictions and regulators to provide input into NHMRC’s program of work on water,” a spokesperson said.

“This includes: states and territory Chief Medical Officers … NHMRC’s membership on enHealth … and membership to the Department of Agriculture and Water Resources’ Water Quality Policy Sub-Committee.”

But it’s an approach that has room for improvement, according to Dr Janet Tang from the University of Queensland’s Queensland Alliance for Environmental Health Sciences (incorporating the former Entox).

“Scientists are being really proactive in letting the panel and regulators know these chemicals are emerging and are the subject of concern, but because of limited funding and resources they can’t take all of our advice,” she said.

However, Chair of the Environmental Health Standing Committee, Associate Professor Sophie Dwyer, said emerging and micropollutants were not a high priority.

“In trying to deal with health risks of emerging contaminants, you’re usually working at what I call ‘the edge of evidence’; there’s suggestions there might be health risks, but it’s unclear,” said Dwyer, who is also the Department of Health Queensland’s Health Executive Director, Health Protection Branch, Prevention Division.

Managing the transition

If a substance of concern is not yet listed, the ADWG outlines a hierarchy of documents to consult, starting with the Australian Guidelines for Water Recycling (Phase 2), then the WHO Guidelines for Drinking-Water Quality.

When Hunter Water began dealing with suspected carcinogenic water contaminants from the Williamtown RAAF base, it consulted number five on the list of acceptable documents: the United States Environmental Protection Agency guidelines.

“For reticulated supplies, the Australian guideline doesn’t apply. That’s created some real issues in the community to understand why those differences exist,” said Hunter Water Chief Operating Officer Darren Cleary.

“Many new chemicals of concern would already be in our screening program, and we would already have some background information on their prevalence and concentration in the region,” Cleary said.

“If required, an assessment of the removal or formation through water treatment and distribution would be  undertaken, and – if also required – there would be monitoring of drinking water.”

Reducing risks

With the emergence of these pollutants, as well as an expected increase in recycled drinking water, it’s more important than ever to monitor and remove contaminants from the water cycle.

CRCWQT research shows standard drinking water treatment technology generally provides sufficient barriers to prevent unsafe exposure to headline-grabbing substances such as antibiotics and hormones.

But as Seqwater’s Duncan Shillito noted: “The effectiveness of removal of any single analyte is strongly dependent on its affinity with water and how effective the conventional or advanced water treatment plant processes are at either settling, filtering, oxidising or biologically changing the micropollutant to reduce its concentrations.”

Like many utilities, Seqwater is ramping up its monitoring, with targeted micropollutant testing. It has currently expanded its list to include 155 different substances and a non-targeted library of an additional 3000-plus substances.

In 2014, the utility switched from grab sampling to passive samplers, which are deployed for 28 days at a time.

“This gives a more holistic understanding of the micropollutant load of polar and non-polar chemicals under both summer and winter conditions, as well as during short seven-day rainfall events,” Shillito said.

Although public concerns about wastewater and stormwater re-use are putting the spotlight on pollutant levels, experts say there is no cause for such concern, as recycled water is already subject to much greater scrutiny and high-tech treatment processes than many other water sources.

“Australia is doing very well,” Tang said. “Even at the [Queensland] Western Corridor Recycled Water plant, all the testing – no matter if we do it from a chemical side or from a biological side – passes all the standards.”

CH2M’s John Poon said: “You’ve got to remember these chemicals are at very low levels – you’re talking parts per trillion, and they’re surprisingly common. Otherwise, we’ll end up investing billions of dollars on treatment plants and upgrades with no sound reasons.”

Guidelines in coming years

Disinfection by-products (DBPs) – which have been linked to low-level risk of bladder cancer – are currently looming large on the CRCWQT radar.

“We can cause much more harm by not having sufficient disinfection but guidelines would be helpful when you’ve got to manage disinfection by-products because of organic load,” said enHealth Chair Sophie Dwyer.

The overall toxicity of chemical mixtures is another concern that is drawing attention, said UQ’s Tang.

“Maybe individually they’re below the guideline level but when they’re mixed together in a cocktail at low concentrations they might cause some toxicity,” she said.

Tang suggested that enhancing import regulations could keep many chemicals out of that cocktail – or at least help monitoring efforts.

“We need better labelling and import transparency so utilities at least know what chemicals they might expect,” she said.

Dwyer predicted that guidelines might move towards a different style of target for chemicals in future. “I think the important conversation going on right now is around  health-based targets – it’s certainly there for microbial reasons, not necessarily for chemical,” she said.

“But that sort of philosophy – where you look at your source water, the risks and then you implement controls suitable for the risks – I think that’s where we’re heading.”

While future guidelines, testing regimes and technology will strive to keep up with emerging risks, all that effort could be in vain if the industry fails to bring the public along, CH2M’s John Poon warned.

“We can do all the tests and health studies, go to the scientific and engineering communities, build treatment processes – I think that’s the easy stuff to do,” he said.

“What’s harder is to be able to communicate to the public how much effort is taken to make the water safe to use.”

First published in Current magazine February 2017.