A cesspit or cesspool is a sealed holding tank with no outlet and requires frequent emptying. A septic tank separates solids and discharges liquid to a drainage field. A treatment plant provides additional biological treatment. If a supposed cesspit has an outlet or fills unusually slowly, investigate rather than assuming it is sound.
When this guide fits
Clues worth recording
- Emptying is needed very frequently
- The seller uses “cesspit” and “septic tank” interchangeably
- No outlet or drainage field can be identified
- The tank level behaves unexpectedly
Three different systems
Cesspits retain all sewage. Septic tanks settle it and rely on soil treatment. Package plants treat it more fully using powered or passive processes. Covers alone rarely identify which is present.
Running implications
A sound cesspit can need much more frequent tanker visits because nothing leaves through an outlet. It must be watertight, adequately sized, ventilated, accessible and fitted with safe warning arrangements where required.
Buying or selling
Request installation and emptying records, location and capacity, and ask how the system was identified. Your conveyancer should check title rights and local requirements. A leak is not an acceptable way for a cesspit to lose volume.
If you are unsure
Arrange safe inspection and tracing. Do not enter the chamber or test an unknown system by flooding it with water.
A sealed tank that rarely needs emptying may be leaking; a tank with an outlet is not operating as a cesspit.
Questions homeowners ask
What people usually want to know
Is a cesspit illegal?
Not automatically. It must be correctly installed, sealed, maintained and emptied, and local planning or building requirements apply.
How often does a cesspit need emptying?
That depends on usable capacity and wastewater volume, often far more frequently than a septic tank. Use level monitoring and records.
Is a cesspool the same as a cesspit?
In UK homeowner guidance the terms are commonly used for the same sealed sewage holding tank.
Sources & review
Evidence behind this guide
Reviewed 1 September 2026. We use primary guidance where available and label trade-body advice clearly.