I work in the drainage industry, you may have seen my employers yellow lorries running around. My job takes me to sewage works and pumping stations all over the south-east of England. Further to Mike and Lyn's points, I've done a job in London where the drains were blocked with chicken bones. It turned out that one of the tenants in a very large block of flats in Central London (EC1 postcode area) was running a food delivery business from their flat. Mind you, I've also jetted live ammunition out of a sewer in Southall too.
I put up a few sewage related posts in the Guess the Place game on the old Forum, one was of a building at Minster-in-Thanet sewage works, the other was of the Combined Sewer Overflow Screen off William Street in Rainham.