# What is a cesspit?
**A cesspit (also cesspool) is an underground, usually brick-lined pit that was used to collect human waste and household sewage.** It is the historical predecessor of the modern sewer system. Until well into the 19th century, the cesspit was the standard solution for waste disposal in towns and cities.
## Construction
A traditional cesspit consists of:
– **Brick or stone-lined walls** — round or rectangular in plan
– **Open or semi-open base** — allowing liquid to soak into the ground
– **Cover or access opening** — for periodic emptying
– **Sometimes a brick vault** — as a covering structure
## Relevance for modern construction
### During demolition and new build
– Old cesspits can cause unstable areas in the ground
– They may contain toxic substances or contaminated soil
– Ground investigation is necessary to detect hidden pits
### Foundation problems
– A forgotten cesspit beneath or adjacent to a foundation can cause settlement
– The fill material may consolidate over time
### Archaeological value
Cesspits are valuable archaeological finds, as their contents reveal much about daily life in the past.
## Related terms
– Sewage
– Foundation
– Drainage
– Basement
– Ground investigation
Want to learn more about construction terms? Visit our [knowledge base at fredsdiyplans.com](https://fredsdiyplans.com).