Sewage Treatment System Running Costs in the UK (2026 Guide)
If you’re running a Sewage Treatment System, 2026 brings a welcome change: lower electricity prices and therefore lower running costs compared to 2024. After several turbulent years in the energy market, the UK is finally seeing measurable easing in electricity unit rates, and this directly affects the annual cost of operating sewage treatment plant motors and gearboxes.
For example, the BA, BA‑X, and BB BioDisc models each consume around 525.6 kWh per year, and the BC BioDisc uses 1515.5 kWh per year.
At today’s 2026 rate (27.69p/kWh), that translates to:
- BA / BA‑X / BB BioDisc: ~£145.54 per year
- BC BioDisc: ~£419.64 per year
Had these same systems been calculated using 2024’s typical 29p/kWh, annual costs would have been noticeably higher—£152.42 and £439.49 respectively—showing real, measurable savings simply from the energy price shift.
Electric Cost
Aeration Sewage Plant Electric Cost
A sewage treatment plant that relies on an air blower to process wastewater is designed to run continuously, 24 hours a day, 365 days a year. The level of energy it uses varies depending on the blower’s size. As a guide, typical aeration systems incur the following running costs based on the 2026 UK average electricity rate of 27.69p per kWh, compared with 29.0p per kWh in 2024.
| Population | Blower (W) | Annual kWh | GB Annual £ |
| Up to 6 person | 50 | 438 | £121.28 |
| Up to 10 person | 95 | 832.2 | £230.44 |
| Up to 15 person | 115 | 1007.4 | £278.95 |
| Up to 20 person | 180 | 1576.8 | £436.62 |
Our recommended aeration systems are the:
Klargester BioDisc Sewage Plant Electric Cost
The Klargester BioDisc operates continuously, running 24 hours a day, 365 days a year. Its electricity usage is determined by the motor and gearbox, which power the rotating biological contactor responsible for treating and removing pollutants from your wastewater.
| Model | Motor (W) | Daily kWh | Annual kWh | GB Annual £ |
| BA BioDisc | 60 | 1.4 | 525.6 | £152.42 |
| BA-X BioDisc | 60 | 1.4 | 525.6 | £152.42 |
| BB BioDisc | 60 | 1.4 | 525.6 | £152.42 |
| BC BioDisc | 173 | 4.1 | 1515.5 | £439.50 |
NB 1: Assumption that the blower or motor is operating at full load. Although it is appreciated this is not the situation on all sites, it is the only consistent way of comparing like for like, as each site condition would bring a varied current draw on energy usage.
NB 2: Electric costs per kWh are based on a UK average at the point in time of 27.69/kWh (estimated 2026).
NB 3: Energy consumption does not include cost for running IPS or pumped outlet systems. This would need to be measured on a flow meter as energy consumption is differs dramatically depending on site conditions.
De-Sludging Cost
Emptying is one of the biggest expenses of running a Sewage Treatment System. The emptying, also called 'de-sludging', by a tanker can start at around £195 per minimum of 1000 gallons removed by a licensed contractor.
It is important to note - Do not let a non-licensed person empty your plant - it is illegal and heavy fines can be imposed.
We recommend the below de-sludging cycles for each system based on the manufacturers guidance. If your system is not on the list give us a call on 01388 537 050 and we can advise costs.
| Model | PE | De-Sludging Intervals | Annual Gallons Removed | GB Annual £ |
| BA | 6 | 12 Monthly | 600-800 | £195.00 |
| BA-X | 9 | 12 Monthly | 600-800 | £195.00 |
| BB | 12 | 12 Monthly | 600-800 | £195.00 |
| BC | 18 | 12 Monthly | 1200-1500 | £293.00 |
| BioTec 1 | 6 | 12 Monthly | 700 | £195.00 |
| BioTec 2 | 12 | Every 6 Months | 700 | £195.00 |
| BioTec 3 | 18 | Every 6 Months | 1000-1200 | £234.00 |
| BioTec 4 | 25 | Every 6 Months | 1000-1200 | £234.00 |
Maintenance Cost
All sewage treatment plants require regular maintenance. Most domestic systems only require annual service visits which can start at around £180 +VAT and will depend on the size of your system and your location. It is worth noting that having a servicing contract with an accredited company such as RA Dalton will be the most economical method of keeping your system in line with your manufacturers warranty and compliance with the Environment Agency's general binding rules. If you do not have a service contract in place, you can expect your first engineer's visit to cost anywhere from £200 +VAT as it is outside of their pre-planned preventative maintenance schedule. Once you have a plan in place with a provider the price will usually go down.
Larger systems can need much more frequent servicing. If you have an environmental permit to discharge, in order to comply with your permit you must take out the maintenance plan. You will also require a service plan in place with an authorised service provider to receive warranty on most systems. Unfortunately, electrical and mechanical parts can fail on sewage treatment systems. If this happens Direct drainage is here for you! We offer the a price match guarantee on all sewage treatment spare parts so you can be confident you are getting the best deal. We would highly recommend using a trusted maintenance provider such as RA Dalton Ltd to carry out regular maintenance.
To discuss servicing plans give our friendly team a call on 01388 537 050.
We also supply all spare parts for sewage treatment systems for individuals which can be fit by a suitable person.
Which is the most energy efficient sewage treatment system?
For domestic applications (Up to 25 people) the Clearwater BioAir and Klargester BioTec are considered some of the most economical sewage treatment systems on the market. For larger/ commercial applications the Klargester BioDisc model has been proven to have significantly lower running and maintenance costs than other systems
No.1 for Domestic Running Costs
For domestic dwellings without access to mains drainage, the Klargester BioDisc BA provides quality, reliability and peace of mind and is one of the most popular systems from this leading UK manufacturer, making it our No. 1 choice of Sewage Treatment System.