'Shocking' metallic sludge contaminating Sydney dams that supply drinking water
How Safe is your Drinking Water?Water pollution can be caused in a number of ways, one of the most polluting being city sewage and industrial waste discharge. Indirect sources of water pollution include contaminants that enter the water supply from soils or groundwater systems and from the atmosphere via rain.
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Water that's safe to drink should ideally be clear with no odour, funny or unpleasant after taste. One way to tell if water is contaminated is to look for turbidity, or cloudiness.
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Chlorine is deliberately added to many location water supply to kill germs and pathogens, but when it mixes with other organic compounds it can create a few harmful byproducts.
Here is the article link to the Food Revolution Network on Cancer Risk with Chlorine in drinking water. One of these byproducts, a group of chemicals known as trihalomethanes (THMs), has been linked to kidney problems and increased cancer risk. Another, known as haloacetic acids (HAAs), causes skin irritation and could also increase cancer risk.Low levels of chlorine in the water system can also expose people to a parasite called giardia that causes diarrhoea, cramps, and nausea. Another giardia sign is foul-smelling burping.
Water that smells like bleach could be a sign of excess chlorine in your local system.
Water that smells like sewage or rotten eggs could contain hydrogen sulphide, a colourless gas that can naturally occur in groundwater. When this gas is exposed to certain bacteria, it converts into sulphate, which can cause dehydration or diarrhoea.
A number of contaminants, including arsenic and nitrates, are hidden to the naked eye. In many cases, a single drinking water system will contain more than one hazardous chemical, making it difficult for individuals to evaluate the overall health risk.
Metals like iron, manganese, zinc, copper, and lead can release into local water supplies, giving the water a metallic, or salty, taste. This foul flavour is a warning sign that you may have lead in your drinking water, but in some cases it’s merely a sign of a low pH.
Purification removes most of the contaminants that are in your tap water, filtering dirt, metals, fluoride and harmful bacteria that can be dangerous for your family's health.
Article from the ABC News: IMPORTANT READMetallic sludge is contaminating two dams that supply drinking water to one of Sydney's biggest growth areas, official data from New South Wales' peak water body has revealed.
The data, obtained by the ABC under freedom of information laws, revealed dozens of samples taken by WaterNSW from deep in Cataract Dam and Cordeaux Dam over the past three years showed elevated levels of iron.
Water authorities say the contamination is not a concern because other sources of water are available to "balance water quality and quantity".
But they concede the falling storages of Sydney's dams are posing a serious challenge.
Cataract Dam and Cordeaux Dam directly supply water to the Macarthur region in Sydney's south-west, which is expected to swell to more than 600,000 people by 2026.
The booming area has no access to clean, desalinated water from the Kurnell plant.
Tap water is safe but questions raised about long-term future
The treated water that makes it to people's taps remains safe to drink but the results show the contamination in the dam is worsening.
Cataract Dam is only 26 per cent full, prompting community debate about the long-term supply of clean drinking water during long droughts.
Western Sydney University scientist Ian Wright, who specialises in research into urban water quality, described the results as "shocking" and "unnatural".
He said the pollution was caused by metallic sediments — deep in the dams' catchments — dissolving into the water.
The sediments are a by-product of coal-mining activity, which over many decades has damaged Sydney's rock beds, swamps and streams.
The records show samples from Cataract and Cordeaux dams have exceeded acceptable limits more than 90 times in three years.
By comparison, neighbouring Avon Dam has breached just three times in three years.
Dr Wright said that while small doses of iron are safe to drink, an elevated level usually indicates more dangerous contaminants in the dams.
The deepwater samples also showed levels of aluminium were unusually high in both dams.
Contamination looks like 'sludge or ooze'
A WaterNSW spokesperson conceded "the drought has caused some challenges to water quality".
They described the "variation" as a "common and natural occurrence", and any contaminants were filtered to meet Australian standards.
Rapid changes in currents, water levels or temperature in a dam can trigger the metallic sediment at the bottom of the dams to chemically dissolve, causing contamination of higher water levels.
"It looks like sludge or ooze," Dr Wright said. "It's a very viscous, runny sort of mud at the bottom of these reservoirs."
"Inside this sludge there are salts and minerals, there is iron, aluminium and manganese.
"There is lithium, strontium, barium, titanium. There is going to be zinc and nickel."
The impact of mining in water catchments was last year probed by an independent expert panel appointed by the office of the NSW chief scientist.
The WaterNSW spokesperson said that study "did raise concerns about the potential for metals to enter dams in the long term" but that more research was needed
The Berejiklian Government is reviewing the future of new mining projects in the catchment.
Julie Sheppard, from environmental group Protect Our Water Alliance, said the data from WaterNSW showed "iron levels are through the roof".
"We don't really know the full impacts of mining, but the suggestion is they are serious and ongoing and remain in perpetuity," she said.
NSW Water Minister Melinda Pavey has been contacted for comment.