Tuesday, May 16, 2006

Fears won't wash: We have to learn to trust recycled water

To kick off the discussion, below is an opinion piece that I prepared and the Courier Mail were kind enough to print today. Any feedback welcome.


Fears Won't Wash

We have to learn to trust recycled water, writes Stuart Khan

May 16, 2006

HERE'S a fact that should shock nobody: Drinking raw sewage is bad for you. It will make you sick and soon enough it will kill you. There are many thousands of toxic chemicals in this world and most of them can find their way into sewage by one route or another.

But the most important and irrefutable fact is that dirty water can be cleaned.

Dirty water is constantly being cleaned by nature. If it were not, there wouldn't be a drop on Earth left to drink.

In the 21st century we are fortunate that we can also clean dirty water with technology. Reverse osmosis is a process by which dirty water is filtered clean of almost all dissolved chemicals. By applying a very high pressure, H2O molecules are selectively forced through nanoscopic pores of a synthetic membrane, leaving other chemicals behind.

Trying to squeeze larger chemicals such as human hormones through a reverse osmosis membrane is like trying to push a golf ball through a tea strainer. Reverse osmosis is so effective that some important ions such as carbonate need to be re-added to stabilise the over-purified water.

It is now well acknowledged among scientists that the major hurdle left to overcome for water recycling is not a technical challenge but one of public acceptance. The very concept of recycling treated effluent for drinking invokes a multitude of emotional responses.

Humans are naturally repulsed by the idea of drinking water we perceive to have been contaminated. Thousands of years of evolution have brought a survival disadvantage to individuals who have not shared this repulsion. However, that evolution has been in the absence of modern water treatment technology. The inclination remains as relevant as ever but it is now in our interest to trust good science coupled with excellent risk management practices.

We should not blindly accept that any technology is infallible. When dealing with water recycling we can and must demand that there be measures in place that stringently manage and control potential risks to public health. We make such demands in relation to our traditional drinking water supplies and must demand the same high standards regardless of the source.

Australian drinking water guidelines require thorough risk assessment and management. This involves identifying potential chemical hazards, implementing more than a single barrier to protect us from these hazards, and comprehensive monitoring to ensure that this protection is successful. Exactly the same approach can be successfully applied to any drinking water source including recycled water.

National guidelines are currently being developed for water recycling. However, they do not yet include replenishing drinking water supplies as a use for recycled water. Given the growing interest in such practice, Australian governments must now urgently address this shortcoming.

Australians considering major water recycling projects are entitled to expect properly developed risk-management guidelines. However, once appropriate guidelines are in place, we should be confident that public health will be wholly protected by complying water recycling schemes.

The single lingering impediment to recycled water may be our reluctance to overcome our deep-set fears.

This will require a degree of trust from the community towards scientists, regulators and public officials.

Trust is something that cannot be purchased, but must be earned. The means to earning trust involve honesty, transparency and a sincere opportunity to take part in decision-making.

Australians must now work together to focus on these social dimensions of water recycling to benefit from the significant advantages of sustainable 21st-century water supply systems.

Dr Stuart Khan, Centre for Water and Waste Technology, University of New South Wales


Anonymous said...

Not for drinking, all other purposes are fine, but drinking recycled sewage is disgusting! Anyone in my mind who thinks or beleaves it to be safe, should be locked up for criminal offences to the people of this world.

Greg said...

I'll quote you here:
"Trying to squeeze larger chemicals such as human hormones through a reverse osmosis membrane is like trying to push a golf ball through a tea strainer. Reverse osmosis is so effective that some important ions such as carbonate need to be re-added to stabilise the over-purified water."


I,m not quite sure where you have got your information from about RO membrane technology, perhaps it was Towowomba City Councils Water Futures booklet. You will need to address this issue more scientifically if you wish to evoke any sort of intelligent conversation about the technology and the process which IMO is seriously flawed.

Anonymous said...

OK, Greg. Stuart has his documented his credentials which include a Ph D. What's yours?

Stuart Khan said...

Hmmm.. No offence to the writer of the above comment intended, but I would just like to say that I don't think its relevant. People are entitled to be concerned about their health and the safety of their water supply regardless of what qualifications they may hold. I admit that I listed mine to give some ‘credibility’ to the options that I have given, but I do not believe that that means alternative opinions are any less legitimate. I would prefer to allow the various arguments to be presented on equal terms and judged on their merits.


Melissa Freeman said...

I guess that many people feel we can afford to be narrow-minded in this matter. I have some relatives in Singapore, where recycling water for drinking and everything else has been a reality since 2003. For Singaporeans, national interest is driven by a desire to be independent from neighbouring countries, so that they have less of a hold over Singapore. This is an incentive to be openminded. As well, their politicians weren't afraid to take a lead and drink it themselves.

Straits Times article about water recycling

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