septic tank

American  

[sep-tik tangk] / ˈsɛp tɪk ˌtæŋk /

noun

1. a tank, often underground, in which organic sewage is decomposed and purified by anaerobic bacteria.

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septic tank British  

noun

1. a tank, usually below ground, for containing sewage to be decomposed by anaerobic bacteria

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Etymology

Origin of septic tank

First recorded in 1900–05

Example Sentences

At one point, the cave faced a potential threat when someone attempted to develop the land and convert the cave into a septic tank.

From Science Daily • Apr. 3, 2026

Tougher controls over the spreading of sewage and septic tank sludge to land as fertiliser in farming are also proposed, as are limits on using digestate from anaerobic digestion plants.

From BBC • Feb. 3, 2026

A staffer from lead contractor ECC asks for important property details: Are there septic tank lids or propane tanks that need to be avoided?

From Los Angeles Times • Apr. 20, 2025

There were six beds arranged in three bunk beds, and in one corner there was a septic tank and "a pipe that served as a shower".

From BBC • Jan. 8, 2025

And Sophie still treated me as if I’d crawled in from the septic tank.

From "Schooled" by Gordon Korman

Related Words

• cesspool
• sewer