You may have recently seen Bill Gates drinking water distilled from human faeces. It was on the BBC and all over the web – you can watch him do it here if you missed it. From your toilet to my glass...I got to taste water made from human waste: http://t.co/S4o8pD7Eu3 — Bill Gates (@BillGates) January 6, 2015 And truly, the Omniprocessor machine that his Foundation has helped develop is an inspiration to all of us sanitation engineers. It’s a vision for the future where not only everybody has access to sanitation, but faeces also become a cheap and convenient source of fertiliser and energy. You may not know it, but there is a good chance that you too are already drinking water that has been – at least partially – recycled from wastewater. If you live in London, and enjoy a view of the River Thames from which much of your drinking water comes, remember that Windsor, Reading and Oxford are just upstream, and so are the sewer pipes of their inhabitants. Something to ponder next time you turn on the tap. We in London do not fall ill from this thanks to the development of treatment plants and good sewerage systems. WaterAid is uncovering this story in our Big History Project, tracing how the UK’s cities have become healthier, cleaner places since the advent of sanitation. Gates’ famous drink is also a healthy reminder that sanitation does not stop at toilets. In places where expensive sewers cannot be installed, toilet pits are dug, and must be emptied. The resulting sludge must be transported, treated and hopefully reused. Emptying the sludge is usually the first hurdle, as recently told from WaterAid’s experience in Tanzania. Despite large investments in treatment machines, we are still relying on a £200 ‘Gulper’ pump to empty these pits, as other options are simply too expensive for most residents of poor urban settlements in Africa and Asia. Gulper operators in Temeke, Tanzania, 2011. Credit: WaterAid The Omniprocessor may provide a solution in urban areas where some sanitation exists. But we are still researching options for toilets, pumps and treatment systems that are affordable for the poor, and appropriate for smaller towns that cannot afford complex systems. In Bangladesh, we are developing drying beds for compact sludge from toilet pits. In Pakistan, our engineers are improving septic tanks for slums. More complex machines such as the Omniprocessor do have their place, especially in larger cities. I hope this invention draws interest from African and Asian municipal engineers and planners at the Faecal Sludge Management conference in a couple of weeks (WaterAid will be there). But the glass of water I am drinking right now in London also reminds me of something else. I do not know – or much care -- how my water has been treated, but I trust that the water company and its regulator have done their jobs well. Ultimately, whatever the technology, we must make sure that governments fulfil their role: to help deliver services for all, especially those hardest to reach, and to make sure we can trust these services when we turn on the tap. Rémi Kaupp is an urban sanitation specialist in WaterAid UK’s Programme Support Unit. He tweets as @RemKau For global policy, practice and advocacy updates and discussion, follow @wateraid on Twitter.