It's not the poo, or the rats -- it's the fat. If you've ever cleared a drain clogged with congealed fat, you know how nasty that stuff is. Now multiply that by 7.6 million people.
Rose George ventured into London's 30,000 miles of sewers with a team from Thames Water:
After the ladder, a brick staircase winds down into the depths. But the stairs are impassable because they are covered with blocks of congealed fat. "It's the bane of our lives," says my companion. Congealed fat, from fast-food restaurants and households, causes up to half of the 100,000 blockages a year and costs $10.5 million to remove each year.
The flushers don't mind their work environment. One told me, "Someone says to me, 'But that's shit,' and I say, 'It might be shit to you, but to me it's bread and butter." The smell of human waste passes, but fat always stinks, they say. You get home and shower, and you smell OK, then the smell oozes out of your pores. "Disgusting!"