Nature and Society
August - September 2007 edition

Meeting report 20 June 2007

Recycling Canberra’s water

Three guests gave us much appreciated perspectives which will be useful background for our own submission to the House of Assembly inquiry.

Paul Perkins

Paul Perkins reminded us of two things. First, that recycling water from sewage is an emotional issue and is subject to ‘spin’, politics and adversarial debate; secondly that the ACT already recycles its sewage for discharge into the Murrumbidgee and that this recycled water feeds into the natural environment, irrigation and urban water supplies downstream.

He said that European settlement had brought European ideas and assumptions about the environment to Australia and it was on these that we developed inadequate ‘hydrographics’ (see review of Default Country in the September 2004 edition Nature and Society).

Global climate change contributed to a ‘flip-flop’ about 30 years ago below the 30º parallel. This worked its way into the public consciousness in Perth about a decade ago but we are still largely in denial on the east coast, largely because the change is beyond the past experience of most Australians.

He predicted famines in the northern hemisphere within the next decade, saying that it is now apparent that from 1999 the Iberian peninsula, Turkey and the North China plain had entered prolonged drought and that the high plains aquifers in the US were being seriously depleted. All four of these areas were experiencing their worst drought for a century. In some of these areas more frugal use of water has been accepted; we have not accepted the need for frugality.

Paul counselled us not to be distracted by the present rainy weather but to plan on the basis of climate trends and forecasts.

He said we must increase the effectiveness of our limited and diminishing water supply and that recycling our waste water was one way to do this. Although there was not a high level of trust that either the government or the private sector could recycle with sufficient safety, he pointed out that it was technically feasible in a number of ways and that the community needed to specify the level of assurances it required rather than rejecting it out of hand.

All alternatives include a waiting period while the design and engineering is completed and this implies the continuation of stage 4 water restrictions for the next four summers (at least). The main alternatives under consideration include:

•        building a new dam (which would take four or five years) or expanding the Cotter dam from its present 4.5 to 70 gigalitres and waiting for it to fill. An expanded Cotter dam is the cheapest way of increasing our storage capacity. It would also provide a purifying storage for a water recycling scheme

•        pumping water from the Cotter through Canberra’s mains up into the Googong reservoir and pumping directly from the Murrumbidgee into the Cotter

•  recycling waste water – at the level of the individual house and business as well as at the city level.

Domestic rainwater tanks are admirable but inadequate of themselves; using less water, too, will be inadequate, but both approaches should be part of an organised strategy.

Paul finished by pointing to Canberra’s status as the nation’s capital with a population of 370,000 which will rise to 450,000 in the current planning period as reasons why we have special needs and must progress. He urged Canberrans to avoid blaming the actions of past planners and engineers who did their best in their time. We have to move forward together. Without an effective strategy, Canberra will gradually die.

Deb Foskey

Deb Foskey, Greens MLA, has recently successfully proposed a House of Assembly inquiry into water recycling in the ACT. Submissions are being invited from the public until October and the inquiry is due to finish in March 2008. She said that other parts of Australia have more vulnerable supplies than the ACT and we need to learn from their experiences.

Deb endorsed Paul Perkins’ observations about denial, saying that the recent ACT budget was based on the assumption that rainfall would return to the pattern seen as normal 20-30 years ago. Although there was general agreement that there should be some reduction in water use, so far every class of user has objected strongly when it is suggested that they should be a leader in reduction.

She added to Paul’s list of water options by reminding us that the government was looking into desalinating seawater and pumping it from the coast – just a more extreme example of official preference for centralised, high technology engineering-based solutions. All pumping options are expensive and have high greenhouse costs.

Deb also referred to Actew’s brief to supply water to a Canberra population of 500,000 by 2030 with no thought being given to capping the population at that figure. Housing developments, however, are handled by a separate authority whose plans exclude managing demand for water and assume Actew’s supplies will meet the demand.

She said this was the wrong way to approach the problem. It would be preferable to look at our water resources as a guide to the size of the population Canberra could sustain.

She also mentioned the “Water Smart Tune-up” which she though should be free to households and taken up by real estate agents. Unfortunately, there is no incentive for landlords to improve the water efficiency of their properties as tenants pick up the bill. She discussed the need for flexibility in water restrictions to enable our landscape – particularly street trees – and suburban vegetable gardens to survive. Deb said the Assembly’s committee process is one of its strengths and she encouraged us to make a submission to their inquiry.

Peter Collignon

Peter Collignon, a professor at the ANU medical school as well as a clinician at the Canberra Hospital, told us he was involved in the water debate because of his passion about risk minimization and for avoiding unnecessary risks.

He ranked clean water along with vaccination as the two main features of contemporary public health. Clean water has been possible primarily through chlorination and by establishing clean catchments. Recycling water is directly opposed to the principle of clean catchments. He said he was in favour of recycling Canberra’s water but not for human consumption.

Putting the quantities of water into perspective he said that about 800 GL falls in or flows through the ACT each year, with 300 of those entering the ACT in the Murrumbidgee. We draw about 65 GL from our dams and put about 35 GL back into the Murrumbidgee through the Lower Molonglo treatment plant, which is still one of the best in the world. That is, Canberra extracts 30 GL a year. The recycling proposal is to treat 9 GL annually.

The water flowing from the ACT is held in Burrunjuck Dam and most eventually finds its way to Riverina rice farms that use 2,000 GL – more than all Australia’s capital cities combined. Canberra’s 30 GL is similar to the annual water use of one large rice farm. He made the point strongly that Canberrans should not be exposed to the risks from recycled water just so the extravagant irrigation of rice farms could continue.

Canberra’s Lake Burley Griffin is filled with 5-6 GL of drinking water from Googong, but it could be filled with recycled water from the Molonglo plant.

The reverse osmosis technology proposed for Canberra was, he told us, good—though expensive and requires a lot of energy—and he would accept it if there was no alternative; but there are alternatives. The reverse osmosis technology uses a one-micron membrane to exclude the bacteria, then a finer one in the reverse osmosis. This is supposed to leave only water molecules. In fact it lets through about 2 per cent of the salt and also misses about 2% of viruses, but the data are scarce because other cities generally check for bacteria, but not for viruses. Their tests themselves do not measure water at the consumers’ taps, but in laboratories and using computer models for viral surrogates, rather than measures of viruses themselves. In Brisbane reverse osmosis removes all but about 6% of antibiotics (this is odd because their particle size is much larger than a water molecule), but he would prefer to see that figure below 1% in Canberra’s situation. For nitrates, the figure is between 10% and 50%; this is not especially serious in itself, but it does demonstrate that reverse osmosis does not clean the water as thoroughly as the publicity claims.

If you get rid of 99 per cent of drugs and you heavily dilute the result, is the risk significant? Probably not. But removing just 99 per cent of viruses is a different matter, depending on their initial density.

Technological fixes are not, by their nature, failsafe.

The reverse osmosis process is ‘high risk’ because the low probability of a serious problem has to be weighed against the huge consequences – ‘catastrophic’ – that would follow a significant malfunction, no matter how infrequent a malfunction was. He repeated that it would be ‘high risk’ and added that this risk was additional to all the existing risks.

The financial cost of the proposed scheme is very high: $150m to build the dam and $10-$20m a year, much of it going on electricity, to run the pumps (to elevate the water 268 m), electricity which would, over a year, emit 50,000 tons of carbon in its generation.

About 210 GL a year enters our dams in an average year. In 2006 only about 25 GL came in. This range is typical for Australia and has led to the relatively large storage dams we use in our environment with its extremes of floods and droughts. In other counties they draw water from reliable nearby rivers. These large storage dams give us high quality water as they serve to dilute contaminants and provide time for disease organisms to die off or settle. This system also makes us vulnerable when run-off from heavy rain flows into our reservoirs, stirring up the water and pushing it through the reservoirs relatively quickly. In Canberra’s case water from heavy rains would be pumped through the urban water mains from Cotter to Googong (there is no other route), putting disturbed water into our supply.

It is claimed that Singapore and Orange County in California have systems based on reverse osmosis, but the former’s recycled water is used mainly by industry and the latter’s is stored for a year before being drawn on for general domestic use (Canberra’s plan means there will be occasions when the holding period is down to two days). In Windhoek (South Africa) they use the system, but they have a very low rainfall and no alternative.

For water recycling to be safe in Canberra we need a large dam in which to store the water and we need careful testing of water so it can be kept off-line until we know it is safe.

Question time

In the question time following the talks the following points were made:

• Actew is a good engineering organization, but this means there is a corporate momentum to move from one big, centralised engineering project to another
• Water for recycling should exclude water from Fyshwick, Hume and Mitchell industrial areas
• Actew has ruled out a dual system across the city; however dual systems should be installed in new suburbs
• 50% of Canberra’s waste water is already recycled now, in 2007, but it is discharged into the Murrumbidgee from where it flows into the large Burrunjuck dam and then flows on to farms and for human consumption in cities downstream
• There needs to be more involvement in the debate by people who are well-informed—in contrast to the situation in Toowoomba, when the debate became emotional, political and informed by prejudice. One way through this is for the basic data to be in the public arena in a form where it can be the basis for informed discussion and decision-making
• People latch on to slogans like “I’m not drinking that sh*t” and some journalists sensationalize the story by selecting the facts that make the best story or which set up oppositions that would not otherwise exist
• The need for a new urban aesthetic so that our urban landscape matches our environmental parameters rather than struggling to meet an ideal imported from Europe. Demand reductions up to 20% have been achieved overseas with up to 40% if all gardens are adjusted to meet local conditions
• There is a push for a high-tech takeover of demand management by relying on sophisticated metering rather than fundamental landscape and systemic changes
• Demand management is not attractive and difficult to sell politically, yet Canberra is presently unsustainable
• Some people are committed to a single solution (demand management or more dams) and will not give due consideration to all the possibilities; this tends to harden opposition in those who have more inclusive approaches
• The government encouraged farmers to grow rice so there is a case for government compensation to enable them to withdraw from this out-dated water-intensive industry. The rice farming debate is very political, with powerful interest groups rigidly protecting their positions.
• Daniel Connell’s book The Politics of the Murray-Darling Basin shows that water allocations were made on the assumption that the unusually high rainfall of the 1950s and 1960s was typical
• The viral risks come from a wide range of viruses; enteroviruses (polio, coxsackie virus which causes heart disease), rotaviruses (diarrhoea and vomiting). If stored in healthy dam water for long enough, natural bacteria and fungi will destroy them
• Non-biodegradeable oestrogens should not be sold
• Domestic reprocessing/recycling is increasing, but small-scale distributed systems still need regular informed maintenance and testing to ensure water quality is maintained.

Report by Keith Thomas