Now Wash Your Hands!
Time Out says
Ever stopped to wonder where your drinking water comes from, or where the muck that's discharged from our homes and factories goes to? Well you can find out the answer to both on this two-mile walk along the River Lea, one of London's hardest working waterways. You'll visit the site of the city first reservoir, which is now underneath the Queen Elizabeth Olympic Park, and hold your noses as you pass by Bazalgette's Victorian Outlet Sewer. The grimy focus of this two-mile stroll makes it appealing to children as well as adults. You can register for free tickets on the event page.