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Most of us are lucky to have clean, safe and high-quality water when we turn on the tap. But a Senate investigation into the presence of PFAS, or “forever chemicals,” is putting the safety of our drinking water back in the spotlight. Independent senator Lydia Thorpe, who led the inquiry, says elders in the Aboriginal community of Wreck Bay in New South Wales are “buying bottled water from their aged care packages” due to concerns about the health effects of PFAS in their drinking water. “.
So, how is water considered safe to drink in Australia? And why is water quality different in some areas? Here’s what happens between the catchment area and your tap.
Human interference in the water cycle
There is no “new” water on Earth. The water we drink may be as old as 4.5 billion years and is constantly recycled through the hydrological cycle. It transfers water from the ground to the atmosphere through evaporation and then back (for example, through rain).
Humans interfere with this natural cycle by trapping water from various sources and redirecting it for use. A lot happens before you get home. The quality of water when you turn on the tap depends on many factors, including the local geology, what types of activities take place in the catchment, and the various treatments used to process it.
How do we decide what is safe?
The Australian Drinking Water Guidelines define what is considered safe, good quality drinking water. The guidelines set acceptable water quality values for more than 250 physical, chemical and bacterial contaminants. They also take into account the potential health effects of drinking contaminants over a lifetime, as well as aesthetics – the taste and color of the water.
The guidelines are not mandatory, but provide a basis for determining whether the quality of water supplied to consumers in all parts of Australia is safe to drink. The guidelines are constantly being revised to ensure that they reflect the latest scientific evidence.
From catchment area to tap
Australians’ drinking water mainly comes from natural catchments. Sources include surface water, groundwater, and seawater (through desalination). Public access to these areas is generally limited to maintain optimal water quality. Filtration and purification of water occurs naturally in watersheds as it passes through soil, sediment, rocks and vegetation.
But catchment water is subject to further treatment through standard processes which generally focuses on the following:
1. Removal of particles (for example, soil and sediment)
2. Filtration (to remove particles and their contaminants)
3. Disinfection (for example, using chlorine and chloramine to kill bacteria and viruses)
4. Adding fluoride to prevent tooth decay, adjusting pH to balance water chemistry and aiding filtration.
This water is delivered to our taps through a reticulated system – a network of underground reservoirs, pipes, pumps and fittings. In areas where there is no reticulated system, drinking water can also be obtained from rainwater tanks. This means that the quality of drinking water can vary.
Sources of contamination can come from rainwater tanks from roof catchment areas as well as from taps due to lead in plumbing fittings and materials.
So, does all water meet these standards?
Some rural and remote areas, particularly First Nations communities, rely on poor quality surface water and groundwater for their drinking water. Rural and regional waters may exceed recommended guidelines for salt, microbial contaminants, and trace elements such as lead, manganese, and arsenic.
The federal government and other agencies are attempting to address this. Poor regional water quality has many impacts. These include its implication in the high rates of tooth decay among First Nations people. This occurs when cold, sugary beverages are cheaper and easier to access than good quality water.
What about PFAS?
There is also new concern about the presence of PFAS or “forever” chemicals in drinking water. Recent research examining the presence of PFAS chemicals, as well as their toxicity, in some drinking water catchments in Australia and overseas has prompted recent assessments of water source contamination.
The National Health and Medical Research Council (NHMRC) review proposed reducing limits on four PFAS chemicals in drinking water: PFOA, PFOS, PFHxS and PFBS. The review used publicly available data and found that most drinking water supplies are currently below the proposed new guideline values for PFAS.
However, “hotspots” of PFAS remain where drinking water catchments or other sources (for example, groundwater) have been impacted by activities where PFAS have been used in industrial applications. And some communities have expressed concern about the connection between elevated PFAS levels and cancer clusters in their communities.
Although some PFAS have been identified as carcinogenic, it is not certain that PFAS cause cancer. The link is still under debate. Importantly, assessments of exposure levels from all sources in the population show that PFAS levels are falling, meaning that any exposure risk has also declined over time.
What do you think about removing PFAS from water?
Most sources of drinking water are not linked to industrial contaminants like PFAS. Water sources are therefore typically not subject to expensive treatment processes such as reverse osmosis, which can remove most waterborne pollutants, including PFAS.
These treatments are energy-intensive and expensive and will not be needed based on recent water quality assessments by the NHMRC. While pollutants are everywhere, it is the dose that makes the poison. Ultra-low concentrations of chemicals, including PFAS, although not desirable, may not be harmful and complete removal is not guaranteed.
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