Choosing the right off-mains wastewater system
Homes and businesses not connected to mains drainage need either a sewage treatment plant, a septic tank or a cesspool. The right choice depends on the property, ground conditions and how treated water can be discharged, so site suitability should always be confirmed before anything is installed.
Treatment plant, septic tank or cesspool?
- Sewage treatment plants treat wastewater to a higher standard and are the option most likely to be acceptable where discharge is to a watercourse or where the local environment agency standards apply.
- Septic tanks settle solids and rely on a drainage field to disperse effluent. They suit sites with suitable ground and enough land for the drainage field.
- Cesspools simply store wastewater and are emptied regularly. They are usually a last resort where neither a treatment plant nor a septic tank can be accommodated.
Key buying considerations
- Property size and occupancy: systems are sized by the number of people using them, not just by property type.
- Discharge route: where the treated water can go, and the required treatment standard, drives the system choice.
- Ground conditions: soil type, water table and space all affect whether a drainage field is viable.
- Maintenance: treatment plants need periodic servicing and emptying; factor that into the lifetime cost.
Common questions about sewage treatment and septic systems
What is the difference between a septic tank and a sewage treatment plant?
A septic tank settles solids and allows liquid to disperse through a drainage field. A sewage treatment plant treats the wastewater to a higher standard and is generally required where effluent discharges to a watercourse or ditch. The correct choice depends on your site and the discharge route.
How big a treatment plant do I need?
Systems are specified by the number of residents or users. We confirm the correct sizing against your occupancy and site before supply.
Do I need consent or approval?
Discharges to watercourses and some ground discharges are regulated. We advise you to check current General Binding Rules and local requirements with the relevant authority before installing, and we confirm what is applicable to your project.
Contact us about wastewater management or see our pumping systems.