The GRAF One2Clean 19 Person Sewage Treatment Plant is the largest plant in the One2Clean range. It sits in a single 13,000 litre Carat XL tank and serves small housing schemes, campsites and rural businesses.
Because it is one tank rather than two, there is only one excavation and one set of connections. For more than 19 people, the One2Clean Xtra range goes up to 70 people.
How the One2Clean Plant Works
The One2Clean 19 Person Sewage Treatment Plant treats wastewater in one tank using a simple three-stage cycle. First, sewage flows straight into the biological zone, with no pumping, and air flows through the whole tank so that bacteria start breaking down the waste.
Next, the control unit stops the air and the activated sludge settles to the bottom, leaving a layer of clear water on top. Finally, a one-piece clear water lifter draws off the treated water and the cycle starts again.
There are no pumps, moving parts or electrical parts inside the tank. Instead, the compressor and control unit sit above ground, where they are easy to reach for servicing. As a result, there is very little in the wastewater that can wear out or fail.
Key Features
- Very low energy use, from 0.63 kWh per day
- No pumps, moving parts or electrics in the tank
- Tested effluent quality of 7 mg/l BOD, 14 mg/l suspended solids and 0.5 mg/l ammonia
- Simple, compact control panel
- Quiet operation, so it suits gardens close to the house
- Lightweight Carat tank, easy to lift into place without a crane
What’s Included
- 13,000 litre GRAF Carat XL underground tank with internal treatment parts fitted
- Clear water lifter and aeration system
- Air compressor and control unit
- Mini dome shaft with 150kg pedestrian telescopic lid
Options
- Traffic Telescopic Lid 3.5 Tonne, for driveways and parking areas
- Internal Pumped Outlet, for sites where the outlet cannot fall away by gravity
- External Cabinet M, for the control unit and compressor when there is no garage or outbuilding to house them
In addition, a raised outlet (fitted before dispatch), a warning beacon and a high level alarm are available on request. Please call us to add any of these to your order.
Where Can the Treated Water Go?
Treated water from the plant can usually discharge to a drainage field or, in many cases, to a ditch or stream. In England, the General Binding Rules set out when you can do this without a permit, so check the rules for your site or speak to the Environment Agency before you order. In Scotland, Wales and Northern Ireland, the local environment regulator sets the rules.
Specification
- Population: up to 19 people
- Tank: 13,000 litre GRAF Carat XL
- Dimensions: 4000 x 2420 x 2755 mm (L x W x H)
- Weight: 510 kg
- Loading: Pedestrian as standard, vehicle with the traffic lid
- Tank warranty: 15 years, with a 50 year design life
- Parts warranty: 1 year from commissioning, or 3 years with an annual service
- Manufacturer: GRAF UK
Commissioning and Delivery
A GRAF-accredited engineer commissions the plant free of charge once it is installed, which also starts the warranty. We deliver the One2Clean 19 Person Sewage Treatment Plant free to UK mainland addresses. However, the plant arrives on a lorry, so you will need to be able to offload it on arrival. You can also download the drawing, data sheet and installation manual from this page.








