Using Recycled Water for Drinking

The Australian Government’s National Water Commission (NWC) released a report titled ‘Using Recycled Water for Drinking’ this week. It is publicly available from the NWC website.

The report was prepared by GHD and released as the second Occasional Paper from the NWC’s Waterlines series. It is preceded with a short section describing the NWC’s position on the topic of indirect potable recycling (IPR). This states that the NWC believes that IPR is an important option to improve Australia's long-term water security. It says “The Commission strongly encourages objective and even-handed consideration of IPR as one option for communities to augment their water supplies and to enhance their water security and urges leadership by water decision-makers throughout Australia to enable recycled water for drinking to be considered and implemented.”

On the key issue of risk, The NWC states that it “recognises the risks associated with recycled water for drinking but considers that these risks can be satisfactorily and safely managed. It also emphasises the importance of sound, consultative community decision-making processes, well informed by science and evidence.”

As has become the habit of this blog, the executive summary is pasted below. However the full report is written in very accessible language and well worth reading.

I’d be interested in discussing the details further.



Executive Summary

This discussion paper explores the use of recycled water to supplement drinking water supplies in Australian towns and cities.

This concept involves introducing highly treated recycled water to blend with the source water of an existing water supply. This option may compare favorably with other options to supplement water supplies, but it has only recently formed part of long-term water supply plans in Australia.

Because most of Australia’s towns and cities are sewered, this option is available to most communities. Recycling water for other purposes is happening but is restricted to lower volumes unless new dual pipe systems are added to existing suburbs and houses. Using recycled water to supplement drinking water supplies offers a substantial future water resource for most of our towns and cities. This concept has generated considerable community and industry interest, most notably with the referendum in Toowoomba (July 2006) and the larger scheme for Brisbane which is due to come on line in 2008 to 2009.

The following observations are intended to provide a brief summary of the concepts and ideas in this paper. Each of these observations is explored in more detail in the paper.

This paper is intended for those who are interested in the use of recycled water to supplement drinking water supplies and is not intended to provide a definitive position on this option. The question of water quality and risk to public health is addressed briefly in this primer as it is often raised in relation to this option.

The Environment Protection and Heritage Council (EPHC) and Natural Resource Management Ministerial Council (NRMMC) initiated the development of National Guidelines for Water Recycling (Phase 1, 2006). A second phase of the Guidelines is currently under development and will include the use of recycled water for drinking. More information about these Guidelines are at www.ephc.gov.au/ephc/water_recycling.html.

Background

Introducing recycled water of drinking water standard into the drinking supply source is sometimes referred to as ‘indirect potable re-use’ (IPR). ‘Potable’ is a term used to describe water suitable for drinking. It is ‘indirect’ because it is sent back to mix in with the source water as opposed to introducing the recycled water directly into the drinking water system.

There are many existing water supply systems in Australia and around the world where recycled water enters the source water supply upstream of the off-take for a drinking water supply. This is sometimes referred to as ‘unplanned’ indirect potable re-use. Many towns and cities are already using water sources that contain recycled water. Usually, this is recycled water from some other town or city upstream.

This paper discusses ‘planned’ recycling, where recycled water from a town is sent back to the source for that town. There are around 10 operating or proposed ‘planned’ schemes around the world. Some often-quoted schemes are located in Singapore, Namibia and California.

Queensland and ACT Governments have announced their intention to pursue large scale water recycling to augment drinking water supplies (24 April 2007). The Western Corridor project will be the largest ‘IPR’ scheme in the southern hemisphere and will involve the construction of pipelines to enable the transfer of purifed recycled water from advanced wastewater treatment plants in Brisbane and Ipswich to end users throughout south-east Queensland.

How does the use of recycled water compare to other water supply options?

Until recently, the use of recycled water for drinking water purposes has not been considered in detail in the majority of long-term water supply plans in Australia. However, the degree of interest is increasing rapidly due to current concerns over the future supply of water to our cities. For example, in 2006, the Water Services Association of Australia (WSAA), the peak body of the larger urban water authorities, released a paper that discusses recycling to supplement drinking water, and includes 10 points for consideration (WSAA Position Paper No 2 2006).

Analysis of potential economic and environmental factors shows that there will be cities and towns where the use of recycled water to supplement drinking water supplies compares favorably with other options. This is most likely to occur when the existing wastewater treatment plants are producing high quality water, and are located relatively close to the current sources of water compared to other options.

Using recycled water to supplement drinking water supplies may also have environmental benefits such as reduced energy use and reductions in volumes of waste discharged to the environment compared to other water supply options. Note that depending on circumstances, the remaining waste stream may be more concentrated and contain the same total load of contaminants.

So in some circumstances, using recycled water can have benefits compared to other options. However, understanding whether these potential benefits actually apply to any particular town or city requires a detailed analysis because the costs and environmental impact are unique for each location and water supply system.

What are the risks and how are they managed?

It is reasonable to be concerned about the introduction of recycled water into water supplies. Untreated recycled water can contain contaminants that pose a risk to human health. These risks are proposed to be managed using advanced treatment technologies such as reverse osmosis (which is also used to desalinate sea water) to provide highly treated water, and also by careful operation and management of the entire system.

Schemes typically involve some detention time in either a reservoir or underground aquifer, which is sometimes called the environmental buffer. Processes in reservoirs and aquifers such as detention time and microbial action assist in managing the risks.

Managing risk from a technical point of view involves more than just advanced water treatment. Risk management when introducing treated recycled water into the water supply system extends from the water source (discharges to the sewers) to the customers’ taps. This will include management of risks at the water source, operation of treatment plants, appropriate institutional arrangements, and research and development to keep up to date with best practice. This approach to risk management is outlined in the Australian Drinking Water Guidelines (ADWG) framework for managing drinking water supplies (NRMMC, EPHC and the Australian Health Ministers Conference (AHMC), 2006).

Some specific areas of risk management such as understanding and controlling discharges to sewers, and the extent and nature of the environmental buffer required, can be as important as the treatment process in managing the risk, and in the implications they have for scheme costs and viability.

In Australia, guidelines for using recycled water to supplement drinking water supplies are currently under development. A risk-based approach is being used which has been successful at managing risks in existing drinking water supplies. The guidelines will be crucial in providing an authoritative and balanced view of how to manage the risks associated with adding recycled water to drinking water systems.

Community views

Despite the potential economic and environmental benefits, the use of recycled water to supplement drinking water supplies is sometimes excluded from water supply options analysis based on the perception of community concerns. Social research indicates that a majority of people like the idea of using recycled water in general, however a smaller proportion of people support or accept the idea of use in their drinking water supplies. People are more comfortable with recycled water use outside their homes, rather than in their drinking water.

Research on risk communication has developed lists of factors that often lead to community concern. These concerns are not necessarily ‘technical’, but may be more intuitive and reactive.

There appear to be at least two key psychological factors. First, some people have a reaction of disgust at the idea of using water from this source.

Technical discussions about risk and purity after treatment may not be of interest to people with this reaction. Secondly, some people are more comfortable if they believe the water is more ‘natural’, i.e. has spent some time in a river, lake or groundwater basin.

Communication with the community and scheme design needs to take these factors into account.

Conclusions

In conclusion, the use of recycled water to supplement drinking water supplies appears to offer a potentially appropriate option for some cities to access a significant new source of water that is independent of rainfall. This option may compare favourably with other options on an economic or environmental basis, but this can only be determined by a detailed analysis for each specific case.

Advanced water treatment technologies and new risk assessment techniques should allow water managers achieve the comprehensive risk management that is required to protect public health.

There will be community concerns, and these will need to be addressed through careful planning and a wide ranging approach. Technical education alone is unlikely to satisfy the community. Scheme design may also need to take community concerns into account.

Goulburn Water Group Plan

The Goulburn Water Group (GWG) is a community group established to examine and discuss water management in their city. As it states on their website, the GWG “is an open forum to gather ideas and facts and focus community discussion on Goulburn’s water problems and solutions. Informed and balanced opinion is needed to achieve a sustainable solution.”

It’s no secret that a significant impetus for the formation of the GWG, was a proposal initiated by Goulburn-Mulwaree Council to consider the use of indirect potable water recycling. We gave some discussion to that plan on this blog a year ago. At that time, the National Water Commission had recently granted $50,000 to assist the City Council to undertake a community consultation process to inform the community and gauge support.

I went along to one of the council-organised community meetings in February this year. At that meeting, a range of potential approaches for improved water management were discussed. These included evaporation control for dams, long pipelines from the Wingacarribee Reservoir, non-potable water recycling and indirect potable water recycling.

This week, the GWG took the initiative to release its own proposed plan for Goulburn. The approach was “to identify and prioritise many old and new ideas and blend some of these into one integrated local, permanent, sustainable water plan”.

Accordingly, a broad range of water management ideas are discussed. These include improved stormwater use, refined demand management, improved ability to capture and store extreme (flood) river flows, water storage evaporation control, and the expanded use of rainwater tanks. However, the plans of most interest and relevance to this blog, are GWG’s approach to municipal water recycling. On the topic of recycled water, the GWG plan states:

“The plant at the northern end of the City currently produces treated effluent for limited reuse. ‘Polished’ recycled water could be produced to a suitable standard for unlimited reuse by industry, parks, gardens, irrigation and most importantly environmental flows in the Wollondilly River upstream of the City. The Copford Reach pipeline could recycle water from the sewage treatment and polishing plant back to the top of Marsden Weir. Also recycled water could be piped back parallel with the Mulwaree River to fields and the Goulburn Golf Course. Standpipes along the way could dispense the recycled water for business, building and construction work. Branch lines could bring the recycled water further into the City to Belmore Park. Then the Gaol, North Park, Tully Park and the Police Academy. Around the City sewage pumping stations, particularly in new subdivisions, could be mined with bolt on reuse plants for neighbourhood reuse.”


In other words, the GWG proposes to pipe reclaimed water from an upgraded treatment plant downstream of the city, back upstream. Along the way, the water could be accessed for non-potable uses, thereby off-setting potable water demand.

Of course, it’s important to recognise that under the harsh water restrictions currently imposed in Goulburn, there is very little outdoor irrigation use of potable water, so it will be difficult to make significant savings. However, it is a fair argument that the community would benefit by having the means to irrigate some areas even during severe droughts. Whether specific applications such as the Goulburn Golf Course would be considered to be a suitably high priority for limited water resources, would be a matter for the community (not me!) to discuss.

In addition to these city-based non-potable uses, the GWG plan proposes to use reclaimed effluent to enhance environmental flows in the Wollondilly River. The reclaimed effluent would be returned to the river at a point below the city’s drinking water extraction point (normally Rossi Weir). Although it does not appear to be clearly described in the currently available information, I assume that the impetus for returning environmental flows to the river is so that this volume might be re-credited back to the city’s extraction licence.

This concept of “effluent return” credits, may have potential to be useful to Goulburn as a long term strategy. It may allow the city to extract and store increased volumes of water at times when it is available. However, I have previously taken a quick look at this strategy for Goulburn myself. The information that I received from the City Council was that there currently are practically no environmental flows of potable water supplies released from Rossi Weir. Thus there is barely anything available to be saved by effluent return credits under the current conditions.

Or to put it in volume terms, Goulburn currently has a licence to extract up to 5000 ML of water per year. The city tends to take as much of this as is environmentally available in any year. During dry periods, there is practically nothing left over for environmental flows.

So, returning well-treated effluent to the Wollondilly River for environmental flow has an obvious potential for environmental benefit. For this reason, I applaud the concept. However, how it can be expected to contribute to water availability for Goulburn City during the times when it is most needed is not currently clear.

I recognise that there are lots of other good ideas in the GWG plan and that I have focused on only a very limited aspect. You can find further details here and I would be interested to discuss all aspects of the plan if people are interested to raise specific issues.

Prof Don Bursill on Human Error

Prof Don Bursill is well known and very highly regarded in the Australian water industry. Don’s roles have included Chief Scientist at SA Water and CEO of the CRC for Water Quality and Treatment.

Prof Bursill has expressed some fairly strong views about the potential for human stuff-ups (so to speak) when it comes to planned indirect potable recycling. I have heard Prof Bursill say on many occasions that he has no doubt that the technology is available to make recycled water extremely safe, but that the real risks will arise when people fail to do their job correctly.

I find this to be a very difficult risk to evaluate, but I think it’s a fair assumption (if not blatantly obvious) that if we don’t do things correctly, then things will probably go wrong.

My own position is that we must assume that things absolutely certainly will go wrong, and that we must put sufficient safety barriers in place to ensure that public health remains fully protected when they do.

I’d be interested in your thoughts.

Here’s an article from The Age today.


Recycling sewage should be a last resort: expert
By Jewel Topsfield
The Age
June 5, 2007

THE author of Australia's drinking water guidelines has stressed recycled sewage [for] drinking water should be a last resort, warning that people could die if the system failed and there was an outbreak of disease.

Professor Don Bursill yesterday said he was not concerned about the technology, but human error. He said six weeks ago in Spencer, Massachusetts, plant operators mistakenly released caustic soda into the town's water, causing a shutdown of supply.

More than 80 people were rushed to hospital, suffering burns and eye problems.

Professor Bursill, the CEO of the Cooperative Research Centre for Water Quality and Treatment, said sewage had very high levels of human pathogens "alive and kicking and ready to infect people".

Professor Bursill told a Senate inquiry that international water expert Dr Steve Hrudey had analysed 98 water-borne disease outbreaks, including a disaster in Walkerton, Canada, when seven people died and 2300 became ill from E.coli. "Eighty per cent of the failures he recorded were not due to failures of technology … but were due to human error," he said.

These included lack of attention to operating procedures, lack of maintenance of critical equipment, poor operating training and deliberately suppressing information to avoid problems with regulators.

Professor Bursill said complacency was the biggest danger. He said Australia's regulatory regime was not strong enough to guarantee the safety of a system sourced from sewage.

Queensland Medics on Recycled Water

The Australian Medical Association of Queensland (AMAQ) is Queensland’s peak medical body. The organisation’s website states that they represent more than 5,670 doctors, from residents and registrars through to public and private specialists and general practitioners.

The incoming president of the AMAQ is Brisbane-based urologist and surgeon Dr Ross Cartmill. Dr Cartmill was quoted widely in Australian newspapers today stating that “the AMA is far more than an advocate for issues for the medical profession...It fundamentally is an organisation which is a mouthpiece for our patients.”

Dr Cartmill expressed the opinion that it was time for the AMAQ to raise public awareness of issues affecting the broader community.

The Sydney Morning Herald (among others) reported:

Dr Cartmill said he also planned to tackle the issue of recycled water and allay some of the public fears about drinking water produced from treated sewage.

"I think the AMA needs to take a leadership role in helping the community accept the reality of this situation, especially in south-east Queensland," he said.

But he denied that his broader public agenda was too much to take on, particularly after the leading role the AMAQ took in the reform of the public health system in the wake of the Dr Death scandal of two years ago.

I think a more active role by a broad cross-section of Australian doctors in such discussions of broad public interest (and concern) would be a most healthy development.

The prognosis for a well informed community is encouraging. Sorry…I couldn’t resist the lame pun. I’ll endeavour to keep us up-to-date on any developments from the AMAQ.