This is the second of two articles looking at the increasing reliance of Australian cities on desalination plants to supply drinking water, with less emphasis on the alternatives of water recycling and demand management. So what is the best way forward to achieve urban water security?
An important lesson from the Millennium Drought in Australia was the power of individuals to curb their own water use. This was achieved through public education campaigns and water restrictions. It was a popular topic in the media and in daily conversations before the focus turned to desalination for water security.
Water authorities were also expanding the use of treated wastewater — often a polite term for sewage — for “non-potable” uses. These included flushing toilets, watering gardens, and washing cars and laundry.
Australia has several highly successful water recycling projects.
Sydney introduced the Rouse Hill recycled water scheme in 2001. Highly treated wastewater is piped into 32,000 suburban properties in distinct purple pipes. Each property also has the normal “potable” drinking water supply.
This “groundwater replenishment” adds to the groundwater that contributes about half of the city’s water supply. The Water Corporation of Perth has a long-term aim to recycle 30% of its wastewater.
Southeast Queensland, too, has developed an extensive recycled water system. The Western Corridor Recycled Water Scheme also uses reverse osmosis and can supplement drinking water supplies during droughts.
Demand management works too
Past campaigns to get people to reduce water use achieved significant results.
In Sydney, water use fell steeply under water restrictions (2003-2009). Since the restrictions have ended, consumption has increased under the softer “water wise rules”. Regional centres including (Tamworth) outside of Sydney are under significant water restrictions currently with limited relief in sight.
In a comparison of mainland capitals Melbourne used the least water per residential property, 25% less than the average. Southeast Queensland residents had the second-lowest use, followed by Adelaide. Sydney, Perth and Darwin had the highest use.
Clearly, water pricing can be an effective tool to get people to reduce demand. This could partly explain why water use is lower in some cities.
Water bills have several components. Domestic customers pay a service fee to be connected. They then pay for the volume of water they use, plus wastewater charges on top of that. Depending on where you live, you might be charged a flat rate, or a rate that increases as you use more water.
The chart below shows the pricing range in our major cities.
Flat charges for water per kilolitre (where a kL equals 1,000 litres) apply in Sydney ($2.08/kL), Darwin ($1.95/kL) and Hobart ($1.06/kL).
However, most water authorities charge low water users a cheaper rate, and increased prices apply for higher consumption. The most expensive water in Australia is for Canberra residents — $4.88 for each kL customers use over 50kL per quarter. The cheapest water is Hobart ($1.06/kL).
Higher fees for higher residential consumption are charged in Canberra, Perth, Southeast Queensland, across South Australia and in Melbourne. In effect, most major water providers penalise high-water-using customers. This creates an incentive to use less.
For example, Yarra Valley Water customers in Melbourne using less than 440 litres a day pay $2.64/kL. From 441-880L/day they are charged $3.11/kL. For more than 881L/day they pay $4.62/kL — 75% more than the lowest rate.
Recycled water, where available, is a little bit more expensive ($2.12/kL) in South Australia.
Subsidies are probably essential for future large recycling schemes. This was the case for a 2017 plan to expand the Virginia Irrigation Scheme. South Australia sought 30% of the capital funding from the Commonwealth.
Where to from here?
Much of southern Australia is facing increasing water stress and capital city water supplies are falling. Expensive desalination plants are gearing up to supply more water. Will they insulate urban residents from the disruption many others are feeling in drought-affected inland and regional locations? Should we be increasing the capacity of our desalination plants?
We recommend that urban Australia should make further use of recycled water. This will also reduce the environmental impact of disposing wastewater in our rivers, estuaries and ocean. All new developments should have recycled water made available, saving our precious potable water for human consumption.
Water conservation should be given the highest priority. Pricing of water that encourages recycling and water conservation should be a national priority.
You can read the first article, on cities’ increasing reliance on desalination, here.