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; GOV.UK gives once a month as an example. It must not leak or overflow and must be emptied by a registered waste carrier. Approved Document H expects a new one to be watertight and ventilated, to hold at least 18,000 litres for two people plus 6,800 litres for each extra person, and to sit within 30 metres of vehicle access.
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. In England you do not need a permit unless the Environment Agency says so, but the cesspool must not leak, overflow or cause pollution, and a new one needs planning permission and building regulations approval. Approved Document H treats a cesspool as acceptable only where no other option is feasible.
How often does a cesspit need emptying?
That depends on usable capacity and wastewater volume, and is usually far more often than a septic tank; GOV.UK gives once a month as an example. Keep an eye on the level and keep 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 13 September 2026. We use primary guidance where available and label trade-body advice clearly.