Thermotolerant coliforms are a sub-group of coliforms that are able to grow at 44.5 ± 0.2°C. E. coli is the most common thermotolerant coliform present in faeces and is regarded as the most specific indicator of recent faecal contamination because generally it is not capable of growth in the environment. In contrast, some other thermotolerant coliforms (including strains of Klebsiella, Citrobacter and Enterobacter) are able to grow in the environment and their presence is not necessarily related to faecal contamination. While tests for thermotolerant coliforms can be simpler than for E. coli, E. coli is considered a superior indicator for detecting faecal contamination…” ADWG
Saltwater solution for drought towns battling brackish drinking water
Bourke resident Fleur Thompson says she’s battled a few health issues this year, including hypertension and kidney stones.
So when she found out her outback town’s emergency drinking water supply was high in sodium she was worried.
“I got some tests done and my kidneys were not functioning at full capacity,” she said.
“The one doctor who I did get to speak to about it was really concerned.
“He was concerned about the rest of town having to deal with it as well.”
Bourke’s drinking water comes from the Darling River.
Last summer it got so low the town had to start using a backup supply of bore water from the Great Artesian Basin, which had elevated sodium levels.
The same thing happened at Walgett, about 200 kilometres away, when the Barwon and Namoi Rivers there dried up.
The Walgett Aboriginal Medical Service and the Dharriwaa Elders Group have both expressed concerns about the potential effect on community health.
Chairman of the Elders Group Clem Dodd said the bore water was not healthy.
“You got to have water. I don’t care who you are — animal or person, you can’t go without water,” he said.
“But too much salt in it [is not good] … you got to get good water.”
The salt in the Bourke and Walgett bore water meets the Australian Drinking Water Guidelines but it exceeds the aesthetic (taste) limit.
There is no health-based sodium limit in those guidelines.
Health authorities contacted local doctors about potential health implications for patients with kidney disease, high blood pressure, heart failure, or who are pregnant.
‘Too much salt’
Jacqui Webster, a salt reduction expert from the George Institute for Global Health, has been working with the Walgett community on improving health outcomes there.
She said, while most salt in the average diet came from food, high salt levels in drinking water was a genuine health concern in these communities.
“Too much salt in the diet increases blood pressure, and increased blood pressure is one of the key contributors to premature death from heart disease and stroke in Australia,” Dr Webster said.
“You’ve got a high proportion of the community who are Aboriginal people, and we know Aboriginal communities already suffer disproportionately from high rates of heart disease, stroke, diabetes, and kidney disease.
“It’s really important that poor diets — including the high sodium content of the water — are addressed.”
Dr Webster said sodium could also make the drinking water taste unpleasant and people may turn to sugary drinks instead, which could compound health issues.
There is currently some water back in the weirs at Walgett and Bourke.
But that water is only expected to last until the end of the year at most.
Bourke Shire Council general manager Ross Earl said if it did not rain the town would have to switch back to a mix of river and bore water.
“We were extremely hopeful that this time we’d be going back to river water full time,” he said.
“But clearly we’re preparing for the worst-case scenario — yet again.”
Heeding the call, but at what cost?
The New South Wales Government has now heeded the concerns of residents who are worried about sodium levels in their bore water.
It has committed several million dollars to remove salt from the emergency bore water supplies in Bourke and Walgett using desalination technology called reverse osmosis.
Deputy Premier John Barilaro said the Government’s first priority was water security but acknowledged there were water quality issues in some areas.
“We’re now moving away from surface water to groundwater and that, of course, is about making sure we don’t run out of water,” he said.
“We know that there are high levels of sodium and that is of concern.
“We know there are no general health impacts from that … but we do advise that for people with any medical condition to go see a local GP.
“But we want to look at long term resolving this issue and that’s why we’re prepared to put the investment in.
“We hope to have this all up and ready to go by September–October this year.”
The director of the Global Water Institute at the University of New South Wales, Greg Leslie, has also been working with the Walgett community and he said the new technology was a worthwhile outlay.
“Treating the water to remove salt is a standard water treatment procedure,” he said.
“In other parts of the country — Western Australia, the Northern Territory, South Australia — communities that are on bore water would use reverse osmosis technology routinely to take salt out.
“The advantage of doing it in a town like Walgett is that you already have 90 per cent of the infrastructure needed for those systems, and the reverse osmosis is just bolted on to the end.”
Professor Leslie said reverse osmosis units could be switched on and off as required.
But Bourke’s Ross Earl said even if the NSW Government foots the bill for the reverse osmosis technology, there would be additional running costs for his council.
“I agree you probably can’t put a cost on someone’s health, but we’d really need to get the costings to see what it would cost,” Mr Earl said.
Walgett Shire Council general manager Greg Ingham said he welcomed any initiative to improve the bore water quality in town.
But he also expressed concerns about potential additional costs.
“We don’t want council and our community to be burdened with ongoing operational costs to run desalination equipment,” he said.
An issue far and wide
Bourke and Walgett are not the only towns on Great Artesian Basin bore water.
Many places in New South Wales and Queensland have been on this bore water for years, such as Moree, Cumborah, Burren Junction, Barcaldine, Birdsville, and Winton.
While the quality of that water varies substantially between locations, there are town water supplies with sodium levels similar to that of Bourke and Walgett.
Lightning Ridge is an oft-quoted example.
Tourists flock to the town’s hot bore baths, which are famed for their potentially therapeutic benefits. But drinking that water is a whole other issue.
There has been no significant public outcry in Lightning Ridge over its drinking water supply and it is not slated to receive a reverse osmosis plant.
But Dr Webster said the health issue remained the same.
“I’ve been contacted by a member of the community in Lightning Ridge who is concerned about the salt levels in the water,” she said.
“I think it’s important that we are considering the long-term implications of high sodium levels in the water — not just in Walgett but in all of the communities where this is relevant.”
NSW Regional Town Water Supply Coordinator James McTavish said, while the concerns of some residents in Walgett and Bourke were valid, the water was safe.
“I’d stress that the water meets Australian drinking water guidelines for safety, but there is an issue associated with the detectability of sodium,” he said.
Desalination has often been more commonly associated with coastal cities, where drinking water supplies are topped up with treated seawater during droughts.
But as parched towns dig for water, it is looming as a bigger issue for inland populations too.
Fleur Thompson in Bourke hopes the local council will embrace reverse osmosis technology and use it to take the sodium out of the town’s bore water.
“The cost for maintaining these systems may be high but the potential health and human cost is higher,” she said.