There was a lovely news item in NZ Herald last week:
Water fit to swim in but not to drink
Water agencies say it is too costly to recycle the millions of litres of water pouring daily into the sea from Auckland's effluent treatment plants.
Higher treatment standards at the two plants serving metropolitan Auckland make the discharge at their sea outfalls fit to swim in, though not to drink.
A claim by the North Shore City Council on Friday that its plant "discharges 99.9 per cent water" prompted a Herald reader to ask why this 68 million litres of water was not being reused.
The reader, Jenny Bickerstaff, questioned whether it could not be used for irrigating council gardens or in car washes, instead of being wasted by discharging it into the ocean.
The Auckland Regional Council member for the North Shore, Dr Joel Cayford, supports the idea.
"The tighter the standard, the more obvious it becomes to provide for reuse," he said.
"Auckland's need for washing and grassland irrigation water during dry periods could readily be met by limited reticulation of highly treated water."
Dr Cayford said reuse of water could delay the time when Auckland's peak demand consumption called for an extra source of water.
Such options included a second Waikato River pipeline and a dam at Riverhead, to the city's northwest.
These options would cost about $200 million each.
But so far, North Shore City Council has only a trial of using water from its Rosedale plant to irrigate nearby trees.
City Water operations manager Steve Singleton said the plant's discharge quality was "very high" but was not fit for human consumption or for, say, watering park grass "because it may raise health and cultural issues".
Steps could be added to the treatment process to make the water drinkable and reused in the water supply, as was done in dry parts of Australia.
But the costs and Auckland's high rainfall made this uneconomic.
A reticulation system from the plant to users would cost about $30 million.
The adjacent Albany and Wairau Rd business areas required a full drinking water standard and potentially would take only 1 per cent of the plant's output.
Watercare Services' plant at Mangere, on the Manukau Harbour, investigated land application of treated wastewater on several occasions, said Watercare chief engineer Jim Hodges.
"The volumes involved at more than 300 million litres a day mean there is insufficient land available within tens of kilometres of the Mangere plant with the required soil types to accept treated wastewater.
"Under winter conditions the land can accept little or no treated wastewater.
"When costs, conflict with other land uses and public perception are taken into account, the option is not practicable."
Mr Hodges said Watercare continued to try to find industries that could use treated wastewater.
In the long term, with improved technology, Watercare's Three Waters strategy expected treated wastewater to become a significant source of drinking water.
Good one. BTW - it's complete crap (pardon my french) that Auckland will need - even in the long term - to be actually sourcing its drinking water from treated wastewater. This is the sort of scare tactics that are typically used to frighten the public. Very irresponsible approach which is outrageous. Both Watercare and North Shore City Councils have been sitting on their hands on this issue for years. "We're doing some trials", is the oft quoted excuse.
Come on guys. That won't wash anymore.
Auckland is water rich compared to cities that do have to recycle treated wastewater for potable purposes. Yes it can be done, and it is safe. But it is very expensive - usually requiring reverse osmosis treatment. But Auckland can go halfway - and reticulate - as Japan does - highly treated wastewater for non-potable purposes. And nearby, Melbourne has been doing this for a while. Here is a Q&A from Melbourne Water's website. They make Watercare look positively Dickensian in attitude.
Melbourne Water Q&A
1 What is recycled water?
Stormwater, greywater, rainwater and treated effluent are all alternative water supplies that, when treated as required, are suitable for a range of purposes. This can include irrigating grazing land and crops, in horticulture, industrial processing, in residential dual pipe schemes, and to keep our public and recreational spaces green. On this website, "recycled water" generally refers to fully treated effluent from sewage treatment plants. Recycled water is a valuable resource. It contributes to conservation of drinking quality water, improves the reliability of our water supplies, frees up water for the environment or growth, and reduces the amount of treated effluent discharged into our bays and oceans.
2. Is recycled water presently in use?
Recycled water is already being used in a wide range of applications, including the irrigation of agriculture, parklands and golf courses.
3. Can households use recycled water?
There are a number of residential developments planned for Melbourne, which will have dual pipe facilities enabling the use of recycled water for non-drinking applications such as toilet flushing and garden watering.
4. Why is recycled water being used?
Water is a precious resource, yet less than 10% of Australia's urban and industrial water is recycled. Melburnians use about 485,000 million litres of potable (drinking) water each year. Much of this is for uses that do not require drinking quality water, and could be substituted with recycled water. Water recycling is a socially, environmentally and economically viable solution to help preserve our drinking water supplies.
5. What are the benefits of using recycled water?
Recycled water has many benefits. It reduces the demand on fresh water and makes use of a precious resource that currently goes to waste. Water recycling schemes protect the environment by reducing the discharge of treated effluent to bays and the ocean.
6. How can recycled water be used?
In general terms, Class C recycled water can be used for crops such as tree plantations, vineyards and general agriculture, and irrigation of golf courses and parklands under controlled conditions. With further treatment to Class A, recycled water can be used on an unrestricted basis for horticulture, irrigation of market gardens and open space recreation, and for garden watering and toilet flushing through dual pipe residential development schemes.
7. Where does recycled water come from?
In most cases around metropolitan Melbourne, the source for recycled water is one of Melbourne Water's two sewage treatment facilities - the Eastern Treatment Plant at Bangholme and the Western Treatment Plant at Werribee, which provide large amounts of recycled water all year round. However, in some cases local treatment plants run by the metropolitan retail water companies also provide recycled water.
Another potential source of recycled water involves extracting and treating sewage along existing pipelines (sewer/water mining). The sewage is treated on location (away from an existing treatment plant) using a localised treatment plant. This solution provides another option for recycling, which can reduce the requirement for new pipelines and therefore increase the viability of some recycling proposals.
Stormwater recycling offers another on-site recycling option, with treated recycled rainwater used for non drinking water domestic applications.
8. What happens to treated effluent at present?
The majority of Melbourne's sewage is treated at Melbourne Water's Eastern and Western sewage treatment plants and discharged as treated effluent into Bass Strait and Port Phillip Bay. Approximately 11.3% of the total flow is recycled at present. In addition, large flows from the Western Treatment Plant are used for environmental flows for complex onsite wetland habitats.
Through the increased use of recycled water, we will be able to further reduce the volume of water discharged and use it in applications beneficial to the environment and the community.
9. Is recycled water safe?
Yes. Recycled water undergoes high standards of treatment to ensure it is fit for its intended purpose. There are standards that apply for its use. Regular monitoring and reporting is required to ensure the quality of water being supplied is fit for use.
10. Are there guidelines for recycled water use?
Yes. Recycled water can be safely used for a variety of purposes appropriate to the level of treatment it has undergone, in accordance with EPA Victoria's Guidelines for Environmental Management: Use of Reclaimed Water.
These standards are in line with interstate and international practice and permit a wide range of applications. Individual water recycling projects each require an Environment Improvement Plan, which complies with the requirements of EPA Victoria Visit EPA Victoria: http://www.epa.vic.gov.au/
11. How is recycled water defined?
Recycled water is defined as water that has been treated to a 'fit for purpose' standard for a specific application. The following water classes can all be used to replace potable water and, if used in an EPA-approved fit-for-purpose application, can be classified as recycled water:
Class Range of uses (uses include all lower class uses)
A Urban (non-potable): with uncontrolled public access.Agricultural: eg human food crops consumed raw.Industrial: open systems with worker exposure potential.
B Agricultural: eg dairy cattle grazing.Industrial: eg wash down water.
C Urban (non-potable) with controlled public access.Agricultural: eg human food crops cooked/processed, grazing/fodder for livestock.Industrial: systems with no potential worker exposure.
D Agricultural: non-food crops including instant turf, woodlots, flowers.
EPA Victoria: Guidelines for Environmental Management, Use of Reclaimed Water, September 2002
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