Changing Our View on Recycled Water Usage

As World Water Day 2019 approaches, it is fitting to reflect on this year’s theme of ‘Leaving no one behind’, which echoes the central promise of the 2030 Agenda for Sustainable Development that everyone must benefit as sustainable development progresses.  

Something worth thinking about is that a lack of water doesn’t just impact people’s health but can also have serious environmental and economic effects.  This time last year, Cape Town in South Africa made headlines around the world when it was announced that their town water supply had nearly reached zero after years of low rainfall. Had ‘Day Zero’ arrived, the piped water supply for the city of around four million people would have been switched off and people would have had to queue at one of 20,000 watering points to collect their daily 25L water allowance. Luckily for the people of Cape Town, thanks to drastic water restrictions and subsequent rainfall for two months, Day Zero did not arrive.

A topic that didn’t make a lot of international headlines during the Cape Town crisis was the negative impact to local industry due to the lack of water. Cape Town is not only a large city, but also a major agricultural production area. During the drought, it was estimated that more 37,000 jobs were lost in agriculture, together with more than US$1 billion in production volume.

The impact of water scarcity is being starkly felt around Australia today. Much of Australia is in the grip of a serious drought, likened by some to the Millennium Drought.  

Regional towns are being forced to truck water as their usual water supply, often a mix of surface, river and groundwater, is now depleted. Many farmers across Australia are also struggling with drastic reductions in water allocations.

While our irrigation practices have come a long way, we still see a lot of inefficient water practices today around Australia, because irrigation water is still relatively cheap. During times of drought, irrigation water prices increase significantly, reaching more than $400 per megalitre, whilst during good rainfall years they can drop as low as $20 per megalitre. It is usually during serious water shortages that attention turns to the use of alternative water supplies, such as recycled water.

However, alternative water supplies are not without their challenges. They are typically much more expensive compared to existing water sources (often over $1,000 per megalitre) and their uptake in agriculture is slow as a result. Another impediment is that most sources for recycled water are highly urbanised environments (cities), which are not located close to suitable users (farmers). The cost of transporting the recycled water from city to farmer can also be prohibitive in many cases.

The use of recycled water for agriculture in Australia has been largely based on the traditional disposal model, rather than an economic development model. Treated water sourced from local sewage treatment plants is often provided to nearby agricultural and other users to reduce discharges of wastewater to local rivers and coastal waters. Due to increasing environmental constraints, it has been more economic for water authorities to follow this disposal model, rather than invest in more expensive treatment to allow discharges to waterways.

Under the traditional model, the treated wastewater is often provided to farmers at a price below cost to encourage uptake. This low price is generally reflected in the quality of the treated water, which can also limit its potential uses. Cheap water also reduces the drivers for implementing water efficient growing practices. This in turn means that growers cannot support the use of high-cost water, such as unrestricted quality, recycled water that may be produced by desalination and other technologies.    

There are several recycled water schemes in South Australia that provide higher quality water at a commercial price to agricultural producers. One is the privately owned and operated Willunga Basin scheme that supplies recycled wastewater from an urban treatment plant to vineyards in the McLaren Vale. The drought-resistant water supply has allowed growers to expand their production, underpinning considerable local regional development, whilst greatly reducing wastewater discharges to the Gulf.

As the impact from climate changes increases, rain fed agriculture and food production are at risk from more frequent and prolonged droughts. Combined with an increase in the global demand for food, we need to find smarter ways to use the water that we have available.  Changing the way we view the use of recycled water for agriculture is a good starting point.