Demand for water in Australia could increase by 1.5 trillion litres over the next 50 years, a new report forecasts. The urban water industry's peak body estimates that an extra one trillion litres of water will be needed by 2056, if the population reaches 31 million people. But if the population grows to 45 million, water demand will be 1.5 trillion litres, according to the Water Services Association of Australia report. The association's executive director Ross Young said that a diverse portfolio of water sources will be needed to cope with demand. "Desalination, recycled water, groundwater, water trading with the rural sector, stormwater, rainwater tanks," he listed, adding that new technologies, including waterless washing machines, would also play a role.