Choosing the right sewage treatment plant is not simply a case of picking a unit that fits into the available space. The system needs to be large enough to handle the amount of wastewater a property is likely to produce, both now and in the future. An undersized plant can struggle to treat waste effectively, while an unnecessarily large system may cost more to install and maintain.
So, how do you work out what size sewage treatment plant your property actually needs?
Start With the Number of People Using the Property
One of the most important factors is the property’s population, usually referred to as its population equivalent or PE. This represents the number of people whose wastewater the treatment plant will need to process.
For a residential property, the calculation is generally based on the number of bedrooms rather than simply counting the current occupants. This helps make sure the system can cope if more people move into the property or if it is sold to a larger household in the future.
A small two-bedroom home, for example, will normally have very different treatment requirements from a large six-bedroom property.
Think About How the Property Is Used
The type of property also matters. A permanent family home produces wastewater relatively consistently, while a holiday cottage may experience periods of very low use followed by busy weeks with several guests.
Commercial properties can be more complicated. Hotels, offices, pubs, restaurants and campsites may all produce very different quantities and types of wastewater. Their treatment systems therefore need to be sized according to expected usage rather than bedrooms alone.
When choosing a sewage treatment system, it is important to select a model designed to cope comfortably with the property’s expected maximum demand.
Allow For Future Changes
It can be tempting to choose a system based only on the property’s current requirements, but it is worth thinking ahead.
Are you planning an extension? Could another bedroom be added? Might an outbuilding eventually become guest accommodation? If the number of people using the property is likely to increase, choosing a system with suitable capacity now could avoid more expensive alterations later.
However, bigger is not automatically better. Sewage treatment plants are designed to operate within particular loading ranges, so installing a plant that is far larger than necessary may not always provide the best performance.
Consider the Installation Site
Capacity is only part of the equation. The site itself will influence which sewage treatment plant is suitable.
Factors to consider include:
Local regulations and environmental requirements may also affect how and where treated wastewater can be discharged.
Get the Sizing Right from the Start
Correct sizing helps a sewage treatment plant work efficiently, reliably and within its intended operating limits. It can also reduce the likelihood of unpleasant smells, poor treatment performance and avoidable maintenance problems.
Before purchasing a system, calculate the property’s likely population equivalent and consider any future changes to occupancy or use. For anything beyond a straightforward residential installation, speaking to an experienced sewage treatment specialist can help ensure the system is properly sized for both the property and the site.
Taking the time to get the capacity right from the beginning can make owning and maintaining a sewage treatment plant considerably easier in the years ahead.
