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

The science shows the pollution problem in Lough Neagh comes largely from agriculture, with some from wastewater processing, septic tank seepage and industrial pollution around the shores.

From BBC • Sep. 9, 2025

Firefighters rescued a woman who fell about 25 feet into an out-of-use septic tank in Fontana on Thursday morning, authorities announced, adding that she was conscious throughout the ordeal.

From Los Angeles Times • Feb. 8, 2024

Neighbor Ron Alexander thought the smell was coming from a septic tank, adding that Wednesday night’s blur of law enforcement lights “looked like the 4th of July.”

From Seattle Times • Oct. 5, 2023

We did our summons after dark, at a twenty-foot-long pit in front of the septic tank.

From "The Battle of the Labyrinth" by Rick Riordan

Related Words

• cesspool
• sewer