When planning to build or renovate a private house, dealing with wastewater is a priority. When looking into the cost of biological treatment, it’s important to understand that the total investment includes not only the plant itself, but also its installation and long-term upkeep.
In this article we give a detailed overview of the cost items so you can plan your budget accurately and without unpleasant surprises.
What makes up the cost of a biological treatment plant?
The total estimate is usually divided into three main stages. Understanding each of them helps you make an informed decision that will save money in the future.
1. Buying the plant (technology)
The price is mainly determined by the plant’s capacity (number of people in the household) and the volume of wastewater treated. The AUGUST AT series plants offered by LZT Latvia stand out with 98.2% treatment efficiency, one of the highest figures on the Latvian market.
- For small households and summer cottages (1ā4 people): the most popular model is the AT-6.
- For larger families or several houses: more powerful models are used (AT-8K, AT-10, etc.).
2. Installation and materials
Installation costs are the variable part, affected by your property’s terrain and soil composition. They include:
- Earthworks (digging with an excavator).
- Materials (concrete base, pipes, power cables).
- Groundwater lowering works.
3. Design and documentation
For the system to be legal, you need a design approved by the building authority and proof that the plant complies with EU standards (EN 12566-3).
Approximate costs: a standard family solution (AT-8K model)
To give a realistic picture, we have compiled average market prices in 2026 for a standard private-house project:
| Item | Approximate price (EUR) | What’s included? |
| Plant (AUGUST AT-8K) | 2030 | Tank, compressor, control unit, small lid |
| Installation work | 850 – 1 400 | Machinery, labour, installation |
| Materials | 450 – 750 | Pipes, cables, concrete base |
| Design | 500 | Preparing documents and approvals |
| TOTAL | 3 500 ā 4 800 | A complete system, ready to run |
Note: Prices are indicative and may vary depending on the season and the complexity of the site.
Factors that can increase or reduce costs
When choosing the cheapest offer, specific situations that make the process more expensive later are often overlooked:
- High groundwater level: groundwater lowering, anchoring or a raised tank design is needed to stop the tank āfloatingā out of the ground.
- Soil type: building an infiltration field in clay soil is more expensive than in sandy soil, because wastewater has a harder time soaking into the ground.
- Distance: the further the plant is from the house, the higher the pipe and excavation costs.
Why should the cost of biological treatment be judged over the long term?
When buying a cheaper unit (such as an ordinary septic tank), the initial saving may seem attractive. But over 5ā10 years:
- Maintenance frequency: quality plants need sludge removed less often.
- Electricity: an energy-efficient compressor pays for itself within a couple of years.
- Environmental pollution: poorly treated water can contaminate your own or your neighbours’ well water, causing huge losses and odours in the yard.
We also offer Inbank deferred payment, which lets you install a top-class AUGUST plant today and spread the payment into instalments.
Frequently asked questions
Every site is unique, so the best way to find out the exact cost is a consultation with our project manager. We will help you choose the most suitable solution and calculate all the installation costs.
