Fatberg

A fatberg is a rock-like mass of waste matter in a sewer system formed by the combination of flushed non-biodegradable solids (such as wet wipes) with fat, oil, and grease (FOG) deposits.

In any sub-surface pipe, even of the most advanced design, penetration by foreign intrusions such as tree roots is a commonplace cause of a fatberg blockage.

[4] Comprising not only wet wipes and fat, fatbergs may contain other items that do not break apart or dissolve when flushed down the toilet, such as sanitary napkins, cotton buds, needles,[7] condoms, and food waste from garbage disposal units washed down kitchen sinks.

[5] Blocked fat reacts with the lining of the pipe and undergoes saponification, converting the oil into a solid, soap-like substance.

[6] Many U.S. municipalities require restaurants and food processing businesses to use grease interceptors and regulate the disposal of FOG in the sewer system.

[15] Campaigns have been launched against wet wipes because of their effect on sewer systems, including by Surfers Against Sewage, the Marine Conservation Society and other environmental NGOs who called on the UK's Advertising Standards Authority to end “misleading” branding and packaging.