Archive for December 10th, 2008
Greywater, Greywater Everywhere – But not a drop to drink?
The following was first printed in The Last Straw Journal, an international Straw Bale building journal, in their special feature on Water Conservation and Management:
Greywater, Greywater Everywhere – But not a drop to drink?
by Craig Brown – Waiheke Island, New Zealand
To answer one of the questions I get asked a lot, it is possible to treat greywater to potable standard. However, that would be excessively expensive and energy and resource intensive, especially when there are uses for it which do not require the water to be of such a high standard. If lower quality water, produced cheaply, can be used for purposes like flushing toilets and watering gardens, then more high quality water is available for drinking. It is possible to save 70% or even more of your water use by recycling your greywater. At least 50% is very achievable for people who normally water their garden.
There is another benefit: your wastewater system (whether it is an on-site septic tank type system, or a council treatment plant) will have less load on it if you take out the greywater. This can make the difference between a well-mannered septic and a smelly bog or, on a large scale, could help municipalities avoid significant costs in upgrades and operation. There are energy benefits too. In New Zealand 24% of councils’ greenhouse gas emissions result from water and wastewater services because of the large amount of power used to pump and treat it[1].
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Introducing Peak Water and Water Miles
The following was first printed in The Last Straw Journal, an international Straw Bale building journal, in their special feature on Water Conservation and Management:
Introducing ‘Peak Water’ and ‘Water Miles’
by Craig Brown – Waiheke Island, New Zealand
As with energy, there are few parts of the world that could claim to be using their water resources sustainably. I wish to introduce two concepts to help explain why we cannot continue to use water in the way that we do today (that’s what unsustainable means in its purest form – something that we can’t continue to do). The issues can seem very large and the solutions may appear impossible or large-scale, but I hope to demonstrate that, in fact, the required responses are small-scale, but multiple.
The two concepts I want to introduce are undoubtedly not original, although I did think of them myself: Peak Water and Water Miles. I say not original as a quick google search shows that people are already talking about Peak Water. Although I can’t find any discussion about Water Miles, someone has reserved the website www.watermiles.com. I personally have reserved www.peakwater.org.nz and www.watermiles.org.nz and I hope to have something on these sites (with a New Zealand focus) in time for the publication of this article.
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Onsite conference
I presented this paper to the 2007 On site Conference in Armidale, Australia:
K.I.S.S. MY GREYWATER: THE COST OF OVER-REGULATION
I really enjoyed this conference (much more down-to-earth than the NZWWA conference and more intimate). It set me off on the path of learning more about on-site wastewater as a whole. I now run a consultancy business in on-site wastewater system design (i.e. not just greywater) in the Auckland Region.
1 comment December 10, 2008
NZWWA conference paper
Here’s a paper I presented at the 2007 New Zealand Waters and Wastes Association conference:
Greywater Recycling – Risks, benefits, costs and policy
I estimated 300 people in the room by counting the chairs in each row and the number of rows and estimating the occupancy, which was high – there were people standing at the back. I got a lot of people approaching me afterwards to congratulate me on introducing some sanity into the debate (the debate being driven by the Ministry of Health, which wants to regulate greywater recycling out of existance). This paper explains why I think they are wrong on both the risks and the benefits. To date I am unaware of any instance of anyone becoming sick from recycling their own greywater within their own household. There are lots of examples of people becoming sick from the water they get from the tap, or from bathing in water contaminated by municipal wastewater systems. Then there are the climate change impacts of large-scale systems. The operative term here is ‘relative risk’.
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