SAVING WATER: Our series on saving water will continue all summer and finalise with a special report rounding up all our articles and resources. Sign up for our twice-weekly newsletter to stay in touch with all the relevant news on sustainability.
UPDATED: At least four Australians towns, Stanthorpe in Queensland and Murrurundi, Gloucester and Braidwood in NSW, have run dry and are now trucking in water at great expense. UNSW professor Stuart Khan says there’s many options to help drought-stricken towns before resorting to carted water, with some solutions more affordable and sustainable than others.
The southern Queensland town of Stanthorpe officially ran dry on Monday, and is now trucking in water at the cost of $800,000 a month to the state government. Braidwood, 218 kilometres south of Sydney, is also now relying on carted water, as is Gloucester and Murrurundi.
These aren’t the only towns in danger of going dry. Before Christmas, The Fifth Estate learnt that 90 regional towns and communities in NSW were at serious risk of running out of water, with evacuation on the cards as an absolute last resort.
According to NSW Cross-Border Commissioner James McTavish, who has been appointed by the NSW government to keep these places hydrated, there’s a plan in place for keeping each of these towns open, and seemingly endless funding for the task (for now at least).
Emergency pipelines and other water infrastructure is going in, including what McTavish described as a “water grid” from the Macquarie River to the Murrumbidgee.
Many places are considering groundwater sources, including Stanthorpe. Other options are expansions to the existing water network and water recycling.
Stuart Khan, a professor of civil & environmental engineering at the University of New South Wales, agrees that there’s many viable options to get the most out of diminishing water supplies that are yet to be realised.
Bores are one emergency option
Tapping into groundwater sources is one solution, which Khan says a number of towns and cities are seriously considering.
Reverse osmosis plants make brackish brown groundwater drinkable, and are useful during a drought because they are portable and are available to hire according to Khan. But it’s not a good solution long term because groundwater can typically be extracted far quicker than it can be replenished.
In December, bore drilling companies reported a spike in demand in urban areas under level two water restrictions, with customers willing to pay anywhere between $5000 and $10,000 to keep their lawns and gardens alive using bore water.
We’re still not recycling enough water
Types of wastewater treatment are also common in many towns in Australia, with many places using non-potable recycled water to water parks, sports grounds and airports. Khan says there’s barely a country town that isn’t irrigating a sporting field with some sort of reclaimed water.
The problem with recycled water is it can be hard to match demand with supply. Because non-potable recycled water systems are set up for outdoor irrigation, there’s no need for it during times of heavy rainfall. By contrast, there’s a fairly steady supply of sewage coming through regardless of climatic conditions.
This means that demand for non potable recycled water is seasonal and tends to spike during dry periods.
As such, it’s a useful option if there’s somewhere to store it but building a dam just for recycled water is not always a viable or affordable option.
Khan says the best way to maximise the value of recycled water is to purify it enough so it can be put it directly back into the main water supply. It’s very much possible to do this safely, despite community perceptions remaining one of the biggest barriers to this method.
Politicians need to work together for recycling water
Perth is the only Australian city treating wastewater to drinking water standard, with its Groundwater Replenishment Scheme adding about 14 billion litres of recycled water to the city’s aquifers every year. Unlike Toowoomba, where plans to introduce such a scheme were exploited by opportunistic politicians – and consequently abandoned – Perth’s project received bilateral support, even through a change of government.
Khan believes this is one reason the Perth project has experienced no community backlash. He also says it helps that planning took place over almost an entire decade, and the community were “taken along for the ride”.
Interestingly, Khan says we already drink treated waste water from towns up stream – it’s just called something different.
He says what’s known as waste water discharge can be “almost indistinguishable” from a potable reuse scheme, except waste water discharging is usually further upstream and so there’s more dilution.
His understanding is that it’s been easy for water utilities to avoid this conversation but educating communities on the realities of the urban water cycle is fast becoming a priority. That way, the focus can remain on securing a safe and reliable water supply.
Playing a longer game: stormwater harvesting
Stormwater harvesting, where rain that lands on impervious surfaces such as roads is captured and treated, can’t be installed overnight but can be a viable long term strategy for making towns more drought-resilient.
Stormwater can be treated to drinking standards, or treated to the point it can be used for non-potable purposes such as irrigation. It needs infrastructure to catch it and store it, however.
What makes stormwater appealing as a sustainable water source, says Khan, is that during a drought the soil is so dry and hot that when it does finally rain, it soaks into the soil and doesn’t make it into the normal runoff catchments. However, it is possible to catch stormwater during a rare mid-drought downpour.
The NSW town of Orange put in a stormwater system after the Millennium Drought and it’s understood to be a major contributor to its drinking water supply.
The major cost variables
Khan says each town is unique and has different opportunities and challenges when it comes to drought resilience. He says the main variables are the cost of treatment – with sewage understandably more expensive to treat than less-contaminated water sources – and the cost of transporting it long distances.
Water costs huge amounts in money and energy to pump long distances
It can be extremely expensive to pump water long distances, which is why water from desalination plants on the coast are not just pumped back into the main rivers and dams.
Building pipelines themselves also isn’t cheap, with the 270km pipeline from the Murray to Broken Hill costing a whopping $500 million.
There’s a lot of variability in treating brackish groundwater but Khan says it’s pretty expensive at about $1 dollar per kilolitre. The next most expensive treatment option is treating effluent waste water to the point it can be put back in the water supply, followed by treating waste water for non-potable uses at around 50 cents for a kilolitre. Treating stormwater is cheaper again.
Costs are complicated by the infrastructure that is needed to capture and store reclaimed water and stormwater that isn’t fit for drinking.
The cost of the duplicated infrastructure for reclaimed water may mean paying a premium to purify water to drinking standard so it can go straight back into the water supply is actually the more cost-effective choice. For stormwater, the infrastructure to catch it can also be a major cost.