Scotland has less than three decades before our tap water could contain high levels of dangerous chemicals because of climate change.
Scientists say only a few of the country’s 189 reservoirs and lochs used for drinking water won’t be affected by rising levels of dissolved organic carbon (DOC) linked to increasing temperatures.
It could cause major health issues for humans and animals and increased household bills, according to a study by scientists from Aberdeen University, published in Journal of Environment Management.
Dr Richard Dixon, of Friends Of The Earth Scotland, said: “Climate change is going to affect most areas of life and this study reveals it is even going to affect the water we drink.
“At best, the increase in toxic compounds will mean more complexity and expense in treating that water before it can go into the water network but in some rural areas, where treatment plants tend to be simpler and some people get their water direct off the local hillside, this is a potentially serious health issue.
“Even if we can make this water fit for humans to drink, wildlife and livestock will be exposed to increased levels of cancer-causing compounds. This shows why it is so worthwhile to reduce emissions as quickly as we can.”
Scotland has more than 400 drinking water sources, including rivers, boreholes and springs.
The study comes ahead of the COP26 climate change conference in Glasgow in November.
Scottish Government agency NatureScot has already said climate change is the greatest threat to the country’s habitats. It’s expected to cause warmer summers and wetter winters.
The findings show rising temperatures by the 2050s will cause widespread destruction to peatland. The boggy landscapes play an important role in absorbing carbon from the environment.
But with drought in summers followed by wet winters, scientists believe carbon will be freed from the peats and make its way into the nation’s taps.
The study said: “Assuming part of the carbon stored in this area is likely to be lost, we calculated how much of it could be added to DOC in catchments that contain public drinking water reservoirs each year.
“This is a first estimate of the risk for the provision of drinking water from peatlands due to climate change. Our results show a great variability among the catchments, with only a few being unaffected by this problem, whereas others could experience substantial seasonal increase in DOC.
“This highlights the necessity to frequently monitor DOC levels in the reservoirs in catchments where major problems could arise and to take the necessary measures to reduce it.”
Scientists say DOCs are dangerous because during water treatment they can form compounds linked to cancer.
Professor Andrew Watterson, of Stirling University, said they can react in water supplies with disinfectants and create carcinogens associated with bladder, colon and rectal cancer.
He added: “With climate change, peat may now be releasing more DOC into water supplies and this will require more costly treatments if present at high levels.”
The Scottish Greens’ Ariane Burgess said: “As well as being a crucial carbon store which we need to protect and rebuild to keep emissions down, peatlands are an important part of Scotland’s biodiversity network. This study shows the impact degradation can have on our water supply.
“We need to realise climate breakdown is upon us and do everything we can to adapt and mitigate against worst outcomes, reinforcing our infrastructure and agricultural systems.”
Scottish Water said it had already seen a small increase in DOCs.
Simon Parsons, of Scottish Water, said: “We have been monitoring levels of dissolved organics release for our catchments for a number of years and are seeing small increases.
“Where the raw water quality does change significantly, we will improve the capability of our water treatment works so customers continue to receive high-quality, great-tasting water which meets all requirements of our water quality regulator.”
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