How many times have you visited chemical or better compost loos at an event or festival and found the water reservoir has run out and you can't wash your hands? I spotted this clever use of recycled materials at Offgrid Festival in Somerset last year. (Incidently, Offgrid had to be my favourite last year, possibly because I bumped into permaculture author and teacher, Patrick Whitefield, Mr 'Moneyless Manifesto' Mark Boyle, bee campaigner Brigit Strawbridge, film maker Nicola Peel, our lovely editor Marion McCartney, and a host of other wonderful, innovative people as well.)
It is such a simple idea. Take two IBC tanks. You can buy them second hand or you may just even be able to find one on ebay. Place one on top of another. Fill the top tank with fresh, potable water and plumb in a tap with a hose. The bottom tank receives the waste water. Find an old sink at your local recycling centre and bolt it to a piece of plywood. Secure the ply to the IBC container. Plumb the sink's waste pipe into the container.
Obviously this is a temporary solution for a weekend event but it's better than using hand sanitisers. You can also plant soapwort around the containers if you party on that spot yearly!