Water Miles

Introducing Peak Water and Water Miles

December 10, 2008 at 3:38 pm Leave a comment

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.

What is Peak Water?

Peak Water is based on the concept of Peak Oil, which is understood to be the time when the maximum production of oil has been reached and volumes will decline thereafter. If all the earth’s remaining oil was as easily accessible as that which we have already used, or are using now, this would not happen for some time. However, most of the world’s remaining oil reserves are so inaccessible that to extract them would be very expensive (costing far more than it could be sold for today) and in some cases environmentally damaging.

It is likely that we’ve just nearly reached the peak of oil production and therefore oil prices will head ever upwards as demand exceeds supply and acquisition becomes more expensive. This may not be a bad thing as the current level of use has been a major contributor to greenhouse gas emissions and we need to reduce these to avert catastrophic climate change. However, unless demand is reduced or cleaner energy supplies are found, there is likely to be a movement towards even dirtier sources of energy initially. Sometimes Peak Oil is referred to as Post-Cheap-Oil.

Peak Water is similar in that in many places in the world the easily accessible water is being used to full capacity, or indeed beyond full capacity. The High Plains region of the United States is one of those places, which produces a very significant part of the nation’s food crops by irrigating the semi-arid landscape with water from the Ogallala Aquifer. Unfortunately the aquifer recharges very slowly and depletion rates have been measured to be up to 100 times faster than recharge (figures vary widely but none have recharge even close to depletion rates). The population of this area depends on the aquifer for its drinking water and for its economic prosperity.

The US department of Agriculture estimates that 16% of cropland in the US is irrigated, largely in the Western United States[1]. That acreage grows more than half the value of all US crops. Without irrigation food production would dwindle. Already there are farms that can no longer access the aquifer[2] and others that are drilling deeper wells and using more power to bring the water to the surface with pumps. This pattern has been seen in many other places, such as India, where there are booms in groundwater use, followed by busts where entire regions experience crisis as the water runs out.[3] In other locations rivers[4], lakes[5] and even whole seas[6] have dried up as demand for irrigation, industry and domestic supply have exceeded the capacity of the resource.

Like oil, water can be obtained from more expensive and/or dirtier sources, such as a new dam, a pipeline from a more water-rich location (like Alaska or Canada) or by processes such as seawater desalination. One must consider not only the financial cost of these projects, which is substantial, but also the environmental costs on the source location and the energy costs of the pumping or extraction.

Finally, projects like this simply delay the inevitable; the time when there are no more water sources for exploitation and the world goes thirsty – and hungry. ‘Think big’ solutions frequently transfer the burden to other resources; there are no easy answers.

What are Water Miles?

Simply put, Food Miles are a measure of the environmental cost of a food item, which is often related to the distance it has travelled from the source to the consumer but also encompasses the overall environmental impact of its production and transport, including production costs such as feed, fertiliser and pesticides as well as distribution method and distance (including the consumer’s journey). It is usually expressed as a carbon emission. It could also include an assessment of other environmental impacts (such as eutrophication of lakes due to high fertiliser use or stock effluent run-off).

We need a sister concept of Water Miles, which relates to the energy expended or carbon emitted in the sourcing (dams, pipelines, pumping), treatment (chemicals, energy) and distribution (pumping) of water. This concept should extend to wastewater, which has to be collected (pumping), treated (chemicals, energy) and disposed of (pumping). It could also include an assessment of other environmental impacts (untreated or poorly treated effluent entering the harbours, the embodied energy of concrete pipes, plants and dams, etc.).

For example, in New Zealand a percentage of the Waikato River is now diverted to Auckland, the largest city, to meet the water demands. This was a massive project involving a huge number of heavy truck movements, tonnes of concrete and significant ongoing electrical pumping costs. In the Assessment of Environmental Effects (a statutory process) for that project there was no calculation (nor even a mention) of the carbon emissions arising from the construction nor from the operation. In Auckland, this contributes to the fact that the percentage of each council’s greenhouse gas emissions that  result from water and wastewater operations, compared to vehicles, buildings and other sources, is much higher than the national average; between 35 and 40%[7]^&[8], compared with a national average of 24%.[9]

The project is expected to guarantee supplies until 2050 and it was stated that the alternative options considered would have significant environmental costs or were otherwise unsuitable. It was also stated that water conservation was not expected to be able to yield substantial benefits. This begs the question: what is the plan for Auckland after 2050? Further, would consideration of the Water Miles and Peak Water concepts by key stakeholders have led to a more serious consideration of ‘demand management’ solutions?

Big Problem – Small Solution

As discussed, we tend to find water and energy use linked quite closely and we have an existing crisis with both. They may interact in unpredictable ways in the future, but we can expect climate change to bring rainfall that falls in less manageable ways, with large volumes of water landing over short periods, which we cannot capture to recharge surface and groundwater. It may also erode the soil since we have destroyed many of the forest and wetland environments which can perform the task of slowing the pace of the water and retaining that soil. There will also be longer periods of no rainfall and higher rates of evaporation from the soil.

This undoubtedly adds up to a big problem. But does it call for a big solution? I would argue that there is no big solution. Doing anything on a large scale leads to large-scale consequences. If a large supply is over-exploited it needs another large supply from elsewhere to replace it. If a large sewage plant malfunctions or demand overtakes its capacity then serious pollution can result. If desalination of seawater is to be used in a significant way then massive amounts of power will be required – requiring new generation and resulting in higher emissions. And as I’ve said, any fixes of this nature are not addressing the underlying issue of demand exceeding sustainable supply.

No, the solution is small, indeed, the solution is not to do anything much at all, but rather to do – or use – less. We need to reduce our water consumption by fitting economical showerheads, low-flush (or composting) toilets and perhaps using communal, rather than private, swimming pools.

Farmers need to grow crops that are more suited to their environment rather than creating a false environment through use of massive irrigation schemes. Irrigation that is used needs to become more efficient; dripper lines under the ground for example. Systems that encourage farmers to do this need to be developed, including consumer education and purchasing power.

In addition to this, we need to think local on supply and disposal. Very local. In fact, ‘on-site’. We can’t rely on always being supplied with sufficient, cheap water for our current or even our reduced needs. We need to provide as much as we can for ourselves. One way of doing this is to capture rainwater from the roof in a tank. It can be surprisingly clean without any filters and devices, but with some simple technology it can match or exceed the quality of the municipal supply in many areas. It is possible to live off just rainwater in areas with sufficient rainfall and with a large enough tank (I do on Waiheke Island in New Zealand). However, another option is to use the treated town water only for drinking and bathing and the rainwater for other uses, such as clothes washing.

Another option – and one in which I must declare my professional interest – is the reuse of greywater. The more easily reused greywater comes from the bath, shower and washing machine. It amounts to about 70% of the wastewater produced in an average household and is the ‘cleanest’ portion. Dishwashers, sinks and indeed toilets produce lower volumes of water that are less pure. Replacing an existing use of freshwater with recycled greywater can therefore save around 70% of water use.

I favour on-site greywater reuse over wide-scale sewage reuse as the treatment process is much less energy intensive and is able to be performed locally, within each dwelling, avoiding the need to install large-scale infrastructure and to pump the water back and forth. Sub-surface irrigation and toilet flushing with recycled greywater are low-risk activities that do not require expensive systems to achieve. We have been manufacturing a relatively inexpensive system in New Zealand for 15 years that can be run from a small DC solar power system. We are happy that the water produced is fit for the purposes suggested.

I also favour on-site wastewater disposal, where nutrients and water are returned to the land in manageable quantities. If a failure occurs to an on-site system then the outcome is usually just a smelly, boggy garden. If a failure occurs in a sewage treatment plant then the outcome is often a wide-scale release of sewage into waterways. In the last reported year in Auckland 1.8 million cubic metres of sewage was released untreated into the waterways due to malfunctions or outdated infrastructure[10].

One of the problems faced by proponents of local, on-site solutions is that health authorities often deny people the ability to legally use greywater and rainwater (and indeed composting toilets or on-site wastewater treatment systems) based on calculations of tiny potential risks, but force them to use the reticulated system which has known actual risks and, as I’ve argued, is unsustainable due to the higher energy and water demands.

Perhaps the biggest problem however in moving away from the ‘big pipes in, big pipes out’ mentality is that to avoid the next crisis in supply, demand management solutions need to be implemented from now and over a sustained period of time for them to have any impact, but public policy often suffers from inertia as there is no immediate compelling need to save water. By contrast, a new major supply project can come on-stream in a few years. Such investment usually follows a ‘surprise’ water shortage and the time imperative means that again, demand management is overlooked. Concepts like Peak Water and Water Miles if they take hold in the public imagination, like Peak Oil and Food Miles, could offer one way of beginning to influence policy.

Craig Brown is the Business Development Manager of ECOplus, which manufactures a New Zealand designed greywater recycling unit <craig@greywater.co.nz>, www.ecoplus.co.nz. He is moving into sustainability teaching and consulting from his background in Ergonomics and has plans to build a straw-bale house soon.

---

[1] Fisher, M. (2007) Farm Irrigation Blamed for Water Woes. Associated Press. Retrieved 15 March, 2007, from WTOP website: http://www.wtop.com/?nid=111&sid=1080777

[2] Egan, D. and Bergquist, L. (2003) Great Lakes Tempt a Thirsty Nation. Retrieved 15 March, 2007, from Milwaukee Journal Sentinel website: http://www.jsonline.com/story/index.aspx?id=190702

[3] International Water Management Institute (2007) The Socio-Ecology of Groundwater in India. Retrieved 13 March, 2007, from http://www.iwmi.cgiar.org/home/socio-ecology_groundwater.htm.

[4] The Great Ruaha River (2005). Retrieved 13 March, 2007, from http://www.friendsofruaha.org/ruaha_river.html

[5] United Nations Environment Programme (2002) The Disappearance of Lake Chad in Africa. Retrieved 13 March, 2007, from http://www.grida.no/climate/vitalafrica/english/14.htm.

[6] Paul Welsh (2000) The Aral Sea tragedy. Retrieved 13 March, 2007, from the BBC website: http://news.bbc.co.uk/1/hi/world/asia-pacific/678898.stm

[7] Waitakere City Council (2005) City Development Committee Meeting Agenda, 8 December 2005. Retrieved 28 November, 2006, from http://www.waitakere.govt.nz/abtcnl/ct/pdf/citydvlpmt2005/081205ag.pdf

[8] International Council for Local Environmental Initiatives – Australia / New Zealand (2006) Greenhouse Gas Emissions Analysis: Milestone one report. Retrieved 12 November, 2006, from Rodney District Council website: http://www.rodney.govt.nz/council/2006minutes/September/CEA2109_Item9_Appendix1.pdf

[9] International Council for Local Environmental Initiatives – Australia/New Zealand (2006) Communities for Climate Protection – New Zealand: Inventory Report 2006. Retrieved 14 March, 2007, from ICLEA website: http://www.iclei.org/fileadmin/user_upload/documents/ANZ/CCP/CCP-NZ/Measures/CCP-NZ_InventoryReport2006.pdf

[10] Finucane, L. (Ed.) (2005) Auckland Water Industry: Annual performance review 2004/2005. Retrieved 14 March, 2007, from WaterCare Services Ltd website: http://www.watercare.co.nz/assets/Publications/AWI06Final.pdf

Entry filed under: Reticulation vs decentralised systems, Sustainability, Uncategorized, Water recycling. Tags: Auckland, Greywater recycling, ogallala aquifer, Peak Water, Rainwater collection, waikato river, water conservation, Water Miles.