Treated Water Supply On The Cards For Perth
Drinking treated sewage has always been on the nose in Australia.
The “ick” factor has led successive state governments across the country to rule it out as an option and was a key reason desalination plants were built in many capital cities.
But you’re going to have to get over it because once population booms and climate change bites, most Australians will be drinking recycled water, according to urban water experts.
“I believe it will happen in the next decade for one of our capital cities on the east coast,” Water Services Association of Australia executive director Adam Lovell said.
“For Australia to really grow and to have competitive cities and liveable cities, we have to embrace potable reuse as one of our supplies going forward.”
“There are inland towns who came very close to having to build recycled water plants at the end of the millennium drought,” said Stuart Khan, from the Water Research Centre at the University of New South Wales.
“That’s really going to be the next viable option (for those towns) … they will have very few choices and they will be pushing to be able to develop potable water recycling schemes in order to sustain their communities and cities.”
Increasing demand for water needs to be addressed
To grasp how real this prospect is, you only need to look at the population forecasts.
In Sydney, when Warragamba dam is full, the city has about four years worth of water supply.
Double the population, as is forecast in 50 years, and that falls to two years worth of water supply — and that is only when it is full, a scenario that might become a lot less frequent with climate change.
But that is what desalination plants are for, right? Well … only to a point.
In Sydney, most of the 725,000 new dwellings that will need to be built by 2036 to keep pace with population growth will be built in the west, according to the Greater Sydney Commission.
he compass direction changes, but the trend is the same for all coastal capital cities: population growth is moving away from the coast and away from desalination plants.
“Water being non-compressible and quite a heavy substance — it’s quite expensive to transport,” said Mr Lovell.
“Even if you’re looking at Sydney on the coast through to Penrith or from Wonthaggi to the north of Melbourne — you’re looking at 80 to 90 kilometres. That’s really expensive, and it’s a really inefficient way to transport water.”
In Sydney, for instance, infrastructure is only in place to pump desalinated water from the plant in Kurnell to the CBD and eastern suburbs.
Professor Khan said a whole new set of pipelines would need to be built to get desalinated water west of there, where the population growth will be.
“The further you (pump desalinated water) inland, the more you’re working in a direction that is opposite to the way our water supply systems are designed and operate,” he said.
“They pump water from the source — up in the reservoirs, up in the hills — to the coast. And it’s very difficult to actually turn that around.”
It is not impossible for these pipelines to be built to the west, but it will cost a lot of money.
Desalinated water costs roughly twice as much to treat as recycled water, according to Mr Lovell. And that’s before you start adding in the costs of a pipeline.
Professor Khan said it would be much easier and cheaper to recycle water from a wastewater treatment plant close to where water is traditionally supplied from, to make use of existing infrastructure.
“I think in the future that’s the way all big cities will go,” he said.
Mr Lovell agreed.
“In terms of an overall water supply strategy for a city, it’s absolutely critical for the future. It’ll help to form the backbone of water supplies.”
Swallowing the message of ‘toilet to tap’
There are examples around the world where people are already drinking recycled effluent — sewage that is treated to a drinkable standard and then pumped into water storages or directly to consumers’ homes.
They include countries such as Singapore and Namibia, towns in Texas and California, as well as somewhere a lot closer to home.
“The technology is very straight-forward and the risks are almost negligible. The issues are about community acceptance and bringing the community along,” said Sue Murphy, the CEO of the Water Corporation of Western Australia.
Perth’s water management system has been hailed as best practice around the world.
The city is on the same latitude as Cape Town in South Africa, and faces similar climate pressures.
But unlike Cape Town, which earlier this year named a “Day Zero” when water supplies would run out, Perth is forecast to be able to cope with a growing population and increasingly unstable climate.
Perth has two desalination plants that run at full capacity, and since last year has been pumping recycled sewage back into the city’s groundwater.
“In Western Australia, we talk about (recycled water) a lot. We use the phrases that have been traditionally used by the media to kill a plant, like ‘toilet to tap’, she said.
In a nutshell, the Water Corporation takes sewage after it has been through a wastewater treatment plant, treats it again to bring it up to drinking standard and then returns it to the city’s groundwater.
Unlike other Australian capitals, Perth draws most of its drinking water supplies from groundwater.
“We had a 10-year journey here before we even started it, where we did a lot of research,” she said.
“We had a visitor centre with a big trial facility and took thousands of school children and their parents through the visitor centre to try and get people to understand the technology and the risks.”
In 2012, 79 per cent of Perth residents were in support of the scheme, according to a Water Corporation survey.
“I think people can understand the issues clearly and well if you keep the dialogue going. You also need time for change,” she said.
The relatively straightforward introduction of recycled effluent to the city’s drinking supplies is in stark contrast to Queensland.
In 2006, as the millennium drought took hold, Toowoomba famously voted against a recycling scheme.
Despite that, a year later then Queensland premier Peter Beattie commissioned the construction of one of the biggest water recycling schemes in the world in Brisbane, at a cost of $2.5 billion.
The infrastructure was built, but the water has never been released into the city’s drinking supply.
In 2009, under rising media and community pressure, then premier Anna Bligh said the water would not be used until dam levels fell to 40 per cent.
“It’s a sad story,” said Professor Khan.
“But I think that it’s very clear that that is Brisbane’s next water supply. It’s built and it’s ready to go, so there’s no doubt about it, that’s where Brisbane’s going to go as the population grows.”
Perth River cities are already using a form of recycled water
The terminology might be different, but if you live in a part of Australia that uses a river as a water supply such as Adelaide, you are drinking a form of recycled water anyway.
“If you look at the Thames in London, every town and city on the Thames including London puts its treated wastewater into that river and they pull water out of it to drink,” Ms Murphy said.
“So, anecdotally, if you have a glass of water in London, it’s been through six sets of kidneys before it gets to yours. But no one calls that recycling because it’s going through a river.”
But talk of drinking recycled effluent has been seen as political kryptonite outside of Western Australia.
Despite the technology advantages, it is still the policy of many Australian governments not to investigate the use of recycled water going forward.
In fact, in 2013 Sydney Water received a public slap down from then NSW premier Barry O’Farrell for even contributing money to researching it.
Adam Lovell said that stance was threatening urban water security as Australia’s population swells.
“We need to see removal of policy barriers to potable reuse,” said Adam Lovell.
“It is happening, the technology is there…potable reuse happens right now for many millions of people around the world. All options should be on the table.”
Sue Murphy, the woman responsible for selling toilet to tap to Perth residents, said she was in no position to tell other jurisdictions what to do.
“However, I think the community are much smarter than what sometimes governments give them credit for,” she mused.