Can a Septic Tank Work Without Power? Understanding Power Consumption in Wastewater Treatment Systems

If you’re building a house of off mains drainage, then chances are you will need to deal with waste on site which means you may install a septic tank. A septic tank is designed to separate the solids from the waste so that the effluent can be discharged into a soakaway. People tend to think that a septic tank needs power to do is and we are frequently asked will a septic tank work without power?

Septic tanks are designed to run without power but in some circumstances, they may require power. Septic tanks use natural bacteria to break solids down within a tank and a baffle separates the suspended solids in the effluent. Due to recent legislation septic tanks can longer discharge into a watercourse which means every septic tank in the UK in theory should discharge into a soakaway. So there is where a septic tank may require power.

Usually the soakaway will be installed downstream from the septic tank so that the effluent simply flows out of the tank into the perforated pipe. However, there may be occasions where you don’t have the space to install the soakaway downstream from the septic tank so may need to pump the effluent into a soakaway that is installed at a higher level than the tank itself. This is known as a pumped outlet which requires a constant source of power.

What is the power consumption of a one2clean treatment plant?

A packaged treatment plant operates differently to a septic tank and every treatment plant available in the UK requires power. These systems tend to include air diffusers, sludge returns and pumped discharges which require power. However, each system uses different technology which in turn requires a different amount of power.

The system that requires the most amount of power is a rotating disc system. This disc holds media which helps to break down the solids inside the tank however the disc is constantly moving which means in constantly requires power. A one2clean uses sequence batch reactor technology which means it works in cycles or batches and as it works in cycles and there are periods of rest to let solids so sink to the bottom of the tank, it means the system doesn’t require a lot of power. In fact, the one2clean system uses only 46 KwH per person per year.

Callum Vallance-Poole


Marketing Coordinator - Based at our UK HQ in Banbury, Oxfordshire, Callum is responsible for promoting Water Management Systems, Attenuation Tanks, Treatment Plants, Rainwater Harvesting Systems and more!