And it looks like we might have a looming shortage of the former, which could be solved by recycling the latter. Cynthia Mitchell, an Associate Professor from the Institute for Sustainable Futures at the University of Technology in Sydney (UTS), figures we are quite literally flushing a fortune down the toilet, while global ground reserves of phosphorus are unlikely to last more than 50-100 years. And human urine, of which we pass some 500 litres per year, is rich in phosphorus, a key ingredient in agricultural fertilisers. "Urine will soon be too precious to flush down the loo," Professor Mitchell said. "Already in parts of Europe urine separating toilets are being introduced." Apparently all new homes in the local council of Tanum, in south-west Sweden, are required to have urine-separation toilets. That is the pee goes down one tube, and poo another. She goes onto say, "Sweden has set a national target that 60% of phosphorus in organic waste, including sewage, must be recycled. At least 30% of that goes to fertilise agricultural land." The Prof is calling on drought plagued Australia to realise "a revolution in sanitation, as dramatic and far-reaching as the construction of London's sewers during the Industrial Revolution." But first she believes the country needs to escape the poo taboo of outta sight, outta mind. Via ::UTS and ::ABCPS. Source separation for pee and poo has long been a design factor in some brands of compost toilet, because it speeds up the rate of dry composting of human waste, giving the toilets greater capacity.