A Message From The CSIRO

Dr Simon Toze is a Principal Research Scientist at CSIRO Land and Water. He wrote the following opinion piece that was published in today's Canberra Times. I think its a well written contribution to the current public discussion. What do you think?

Research Guides Way Forward
Simon Toze
The Canberra Times
16 April 2007

AS WE ALL know, Australia is waking up to the variability in water supply across the continent and experiencing documentable climate change. The eastern seaboard is still in the grip of the worst drought in living memory. Water levels in dams over much of the country are at critically low levels. Water is no longer taken for granted, but is now widely acknowledged as a precious resource that we need to manage.

The recycling of waste water is seriously being considered by most water utilities as one of several ways to increase their water resources and to provide a buffer against drought. Using water just once and then discarding it is now viewed as wasteful and unsustainable. Reusing water reduces the strain on our existing freshwater resources and is better for the environment.

Technology is now so advanced that waste water can be treated to a level that is better than the water coming out of our taps. But there are other options, so why recycle water? Why expose ourselves to the risks? Waste water has the advantage over other sources such as storm water in that it is available in plentiful amounts, irrespective of climatic conditions. It also has the advantage that it tends to be of a consistent quality, not necessarily a good quality, but consistent. This makes treatment easier than for a water of variable quality such as storm water. The treatment of waste water is less energy intensive than desalination as it contains about 35 times less salt than seawater.

There is a downside. Waste water can contain contaminants that could be harmful to our health. This can include all the wastes and contaminants discarded from our households, ranging from faecal matter containing bacteria and viruses through to medications excreted in our urine. Then there are the cleaning products and other chemicals used in households.

What are the real risks from these contaminants and how effective are the treatment processes? How sure are we that the water utilities can consistently provide us with a safe product? CSIRO, water utilities, universities and government departments have been undertaking research for a number of years to begin to predict the actual risk from many of these contaminants and understand the effectiveness of treatments to remove them from water. Research has also shown that conventional treatment barriers can effectively remove germs that cause illness. Similarly, the removal of heavy metals and nutrients are well documented.

A group of contaminants that has recently come to the forefront of public awareness is trace organics. These chemicals include the sex hormones oestrogen and testosterone as well as chemicals which mimic the activity of these hormones. Other trace organics receiving attention are pharmaceuticals and personal-care products such as shampoo and body cleansers. Less is known about the presence of these chemicals in waste water and the effectiveness of treatment processes to remove them. These chemicals are usually present in such low concentrations that detection is very difficult. For other chemicals it has been difficult to distinguish them from the large number of other organic compounds, some of which are naturally found in tap water. In other cases, such as newly developed medications, they have only been in use for the past few years and detection methods are yet to be developed. Conventional treatment removes many of these chemicals from waste water or reduces them to levels at the limit of detection. In fact, many researchers are now coming to the opinion that their very low concentrations in treated waste water do not pose a human health hazard.

In order to better understand the environmental risks of these compounds, research is being undertaken to assemble better data on the effect of these compounds on native animals in our water ways. The ability of advanced treatment systems to completely strip these trace organics from recycled water is also being closely examined to ensure that humans and the environment are protected. This is especially important as Australian governments and cities move toward the concept of treating recycled water for drinking purposes.

Research efforts to date have also led to the development of new guidelines for recycling water. The new Australian Guidelines for Water Recycling use an internationally accepted risk-management approach, and are currently being extended to address recycling for drinking water. The guidelines recommend that in the design of water reuse schemes there are a number of fail-safe barriers which ensure treatment effectiveness. This means that if one treatment barrier fails, another is able to cope. Control points which alert if a failure occurs are also required, and in many cases are able to shut down delivery immediately a failure is detected in the plant.

This then leads us to the ultimate question. Is it safe for Australians to drink recycled water? The short answer is that with appropriate treatment and safeguards the water is as safe as our current water supplies. Any researcher working on water recycling will admit there is much still to learn. We do know already that the risks are very low, and are probably less than those associated with drinking water already flowing from our taps. Other places such as California, Belgium, Singapore and Namibia are already recycling water for drinking and despite extensive epidemiological studies no detrimental health impacts have been detected. The Australian public can be reassured that government agencies, researchers from CSIRO and universities, and water utilities are not blindly leaping into recycling for drinking purposes but are taking measured, educated steps using sound research to guide developments and the next course of action.

And do researchers like me put our money where our mouth is? Indeed. I have drunk recycled water, and given it to my five year old, and felt perfectly confident in doing so.

Dr Toze is principal research scientist at CSIRO Land and Water.