Fat thickly coats a Thames Water-administered sewer in Reading (map), U.K., in May 2009.
The fat "ceiling" is the result of years of what the company calls sewer abuse—the pouring of food waste down sinks and the flushing of items other than toilet paper and human waste.
Once in the sewers, leftover meat fat gets mixed in with items like makeup wipes, diapers, cotton balls, condoms, and sanitary napkins, said Amy Dutton, a spokesperson for Thames Water, which is responsible for wastewater treatment for various U.K. jurisdictions.
"It all gets caught up with the fat, and the fat congeals," she explained. "And that's what causes the blockage."
(See a picture of a hotel room in a section of sewer pipe.)