Ensuring a safe and sustainable supply of water to New Zealand's biggest city is a significant challenge for Watercare, Auckland Council and the wider infrastructure sector. Beca's Water leaders, Emily Stevens and Jon Reed, discuss key trend and influences on Auckland's water supply and a range of possible solutions to support the city's growth.

Where do we get our water from now, and what are the some of the biggest drivers impacting our future supply?

Jon

— Auckland currently has three main water sources; storage dams in the Hūnua and Waitākere ranges, the Waikato River and an aquifer in Onehunga. While sufficient for Auckland's existing needs, there are a number of key drivers that impact these sources and the city's demand for water. Auckland's growth, with ongoing intensification and higher density housing, has a huge impact on the levels of demand in different parts of the city. We have seen record demands two years running as a result of dry and hot summer weather. As our population, businesses and tourism grows, this demand is rapidly reaching the point of maximum supply, which means to enable future growth we need a new water source.

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Emily — Climate change is another major factor, with predictions for more frequent and potentially more severe periods of drought and extreme weather influencing water storage and the resilience of our water supply network. If high temperatures (such as during our current dry period) become more normal, the periods of high demand may last for longer and be more extreme.

What's needed to move forward?
Jon — We need to carefully manage our existing water sources and plan for new sources that can help us to meet demand in the future. The Waikato River has kept us going for a long time, but more is needed soon. It's a long process to secure new water allocations though. For example, Watercare applied for an increased take from the Waikato River back in 2013, in a case that has not yet been heard.

Emily — It is also not just about finding water — it's about getting it to people as well — which requires some new or upgraded infrastructure, and smarter use of our existing network. Infrastructure being designed and built today will need the flexibility and resilience to last for 100 years or more. It's also important to minimise leakage from the network and help people to use water wisely, so it's not being wasted.

Jon — We are entering a period of uncertainty, where we cannot rely on the past to inform our future plans. This means we need flexible and adaptable solutions that are resilient to what lies ahead.

What are the key decisions that need to be made?
Jon — Watercare is planning for the future; there are studies that describe what's required, with clear plans for investment in new sources of supply. We need to be engaging with communities, planning 30 to 50 years ahead and looking at the long-term costs and benefits of any decision — in both the financial investment and carbon emissions. The increasing use of technology — like smart sensors — can provide accurate and timely data to help guide decision making. This could, for example, lead to a step change in how leakage is managed or customers receive information about how they are using water.

Emily — It is also important to look at how cities overseas are responding to these climate and growth challenges in different ways.

The Victorian Government's desalination plant in Wonthaggi, is a great example of how Melbourne has planned for the effects of population growth and pressures on supply. Another example from Australia is the treatment and reuse of wastewater by the Perth Water Corporation. Here wastewater is treated to drinking water standards before being used to replenish groundwater. This can then be abstracted during drought periods when the yield of other water sources reduces. Of course, these solutions are not necessarily all suitable for Auckland, but we definitely need to be thinking outside the box. We must be prepared to approach our future supply of water in new and innovative ways, while also moving to a zero carbon future. Quite a challenge!

So, where to from here?
Jon — Auckland will need to identify and secure its next source of water, to ensure we can continue to thrive in the future. We have a ready solution in the increased take from the Waikato River, which we will need soon. The most complex question is what comes next? The next source of water is not likely to be conventional; we will need to find a new, large and sustainable source of water to enable Auckland to grow. Considering the importance of iwi consultation and community engagement, and timeframes for planning and consent processes, we need to start making these difficult decisions now. This means looking at all the options, including seeing our highly treated wastewater as a potential resource that we can use in similar ways to other cities around the world.

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Emily — While new sources of supply are identified, Aucklanders can also all play our part in treating water as a precious and valuable resource. Readers should definitely check out Watercare's Water For Life campaign to find out more about the issues and what they can do to reduce household consumption and support more efficient water usage.

• Jon Reed has over 20 years' experience in the water industry in New Zealand and the United Kingdom, with a technical focus and leadership in the long-term planning of water supply. He has a key leadership role at Beca, working with over 160 water planners, engineers and professionals across New Zealand and Australia.

• Emily Stevens has 18-plus years' experience in water, stormwater and wastewater, and leads Beca's Auckland Water team of more than 40 professionals, with a demonstrated passion for hydraulic and operational modelling for water supply networks.