What it is & how it works
A cesspool (or cesspit) is the simplest system of all: a large sealed underground tank with no outlet. It does not treat anything — it simply holds all the sewage until a tanker comes to empty it.
Because nothing leaves the tank except by tanker, a cesspool never discharges to the ground or a watercourse. That makes it the fallback where the ground or the space won't allow a drainage field — but it is the most expensive system to run, because it fills up and must be emptied often.
The rundown
At a glance
- Size & capacity
- Large by necessity, because it holds weeks of flow. Building rules set a minimum of around 18,000 litres for up to two people, plus roughly 6,800 litres more for each additional person.
- Coping with busy periods
- It simply fills faster. More water in means more frequent — and more costly — tanker visits.
- Bleach & chemicals
- Nothing living to harm, but every litre poured in is a litre to be tankered away, so it pays to keep flows down.
- Wipes, sanitary items & fats
- No treatment, so solids just add to what must be removed. Keeping wipes, fats and the like out reduces the cost and the risk of problems.
- Land footprint
- A large buried tank, with clear, all-weather access for a tanker to reach and empty it.
- Water quality & where it goes
- None — there is no discharge. If a cesspool overflows or leaks, that is pollution and against the rules.
- Care & servicing
- Empty it on a regular schedule and never let it overflow. Check for leaks and watch the level, especially in wet weather. Budget for frequent emptying.
- Signs it is failing
- Overflowing, persistent smells, the level rising faster than usual, or damp/contamination around the tank.
Compare
Other systems
Septic tank
An underground tank that settles out solids, then sends the liquid to a drainage field to soak away.
Learn more → Treats the wastePackage treatment plant
Like a septic tank, but with a powered stage that fully treats the waste — clean enough to discharge to a watercourse.
Learn more → Disperses the waterDrainage field
Not a tank — a network of buried pipes that lets treated water soak into the soil, where bacteria finish the job.
Learn more → Treats the wasteFilter / clinker bed
A bed of stone or clinker that settled water trickles over, where bacteria on the surfaces clean it — often added after a septic tank.
Learn more → Treats the wasteReed bed
A planted gravel bed where reeds and the life around their roots polish the water — low-energy, with a wildlife benefit.
Learn more →