Harlequin CAP 18 Sewage Treatment Plant | 16-18 Person
The Harlequin CAP 18 Sewage Treatment Plant is a reliable, high-performance wastewater treatment solution designed for larger domestic properties serving 16–18 people. Using advanced Moving Bed Biofilm Reactor (MBBR) technology, the CAP 18 efficiently treats household wastewater, providing an effective off-mains drainage solution for properties without access to mains sewage.
Combining durable construction, efficient operation and straightforward installation, the CAP 18 is designed to provide dependable wastewater treatment with minimal maintenance. Its compact design and external air blower make it a practical choice for larger homes, rural properties and other domestic applications.
Key Features
- Suitable for properties serving 16–18 people
- Advanced MBBR biological treatment technology
- Manufactured from durable Medium Density Polyethylene (MDPE)
- 110mm inlet and outlet connections
- Integrated lifting eyes for easier handling and installation
- Fully secured 450mm pedestrian-duty, flush-fitting low-profile manhole cover
- External air blower supplied as standard
- Easy access to the bubble diffuser within the tank
- Compact and lightweight design
- Quiet operation when installed correctly
- 12-month service period
- Certified for use in the UK to EN12566-3
- 2-year warranty for registered products
- High pollutant removal performance, producing treated effluent suitable for discharge to a stream or soakaway, subject to the relevant permissions and site requirements
Specification
- Population Served: 16–18 People
- Treatment Technology: MBBR
- Tank Material: MDPE
- Inlet Invert: 550mm
- Outlet Invert: 625mm
- Blower: External 76W
- Power Supply: 230V
- Energy Consumption: Approx. 0.8 kWh/day
- Desludging: Approximately every 12 months, depending on usage
- Certification: EN12566-3
Suitable Applications
- Large detached homes
- Rural properties
- Barn conversions
- Holiday cottages
- New-build homes
- Properties without access to mains drainage
The Harlequin CAP 18 is supplied with a weatherproof external air blower, providing a continuous supply of oxygen to the biological treatment process. This helps support efficient wastewater treatment while keeping operating noise to a minimum.
If you are unsure which sewage treatment plant is suitable for your property, our experienced team can provide advice on selecting the right system. We can also arrange a professional site visit where required to assess your property and recommend an appropriate wastewater treatment solution.
Optional Extras
Low Pressure Alarm – Provides an early warning if the blower pressure drops, helping to identify potential issues before they affect the performance of the sewage treatment plant.




