Package treatment plant
Sewage treatment plant — e.g. Klargester, BioDisc
What it is & how it works
A package treatment plant (often called a sewage treatment plant, or by brand names like Klargester or BioDisc) does everything a septic tank does, then goes a big step further.
It uses a powered mechanical stage — an air pump bubbling oxygen through the waste, or slowly rotating discs — to grow a thriving colony of bacteria that actively digest the pollution. The result is water clean enough to discharge to a stream or ditch under the rules.
Because it does the full job of treatment, a plant can usually discharge to a watercourse where a septic tank cannot. The trade-off: it has moving parts, needs electricity, and depends on those living bacteria staying healthy.
The rundown
At a glance
- Size & capacity
- Rated in "population equivalent" (PE) — one PE is roughly one person's daily load. Domestic units are commonly 4–12 PE; pubs, hotels and other busy premises need a plant sized for their real peak load.
- Coping with busy periods
- Moderate. The plant is designed for a set load; a big surge — a full pub on a Saturday night — can wash out the bacteria and let partly-treated water through. Sizing it for the true peak matters.
- Bleach & chemicals
- The most sensitive of all the systems. The treatment depends entirely on living bacteria, and a slug of bleach, disinfectant or biocide can kill the colony and stop the plant treating for weeks.
- Wipes, sanitary items & fats
- Poor. Wipes, sanitary items and fats clog pumps, filters and rotating parts, and cause expensive breakdowns. Keep them out completely.
- Land footprint
- Compact — often no large drainage field is needed if it discharges to a watercourse — but it must have a power supply and room for a tanker to reach it for emptying.
- Water quality & where it goes
- Good. Full secondary treatment produces clear, low-pollution water that can meet the standards for discharge to a stream or ditch.
- Care & servicing
- Needs an annual service by a competent engineer (blower, motor, settings) as well as regular de-sludging. The power must stay on — it stops treating in a power cut. Follow the maker's service schedule.
- Signs it is failing
- Alarm light or buzzer, no humming/aeration sound, smells, cloudy or smelly water at the outfall, or solids carrying over.
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 → Stores onlyCesspool
A sealed tank that just stores sewage with no treatment and no outlet — it has to be emptied by tanker.
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 →