Septic tank

Septic Tanks vs Treatment Plants: What You Need to Know

For properties and premises which are not connected to the mains, the only way to efficiently remove and deal with sewage over the long term is to install your own system. Both septic tanks and treatment plants are widely used for this purpose in the UK and overseas, but although they perform the same function, these two systems are in fact very different, and suited to different circumstances.

To help you determine whether septic tanks or sewage treatment plants are the best waste disposal option for your requirements, the Drain Doctor team has compiled a quick and helpful guide to the key differences between both options, whether you’re looking for the most eco-friendly solution, or the system which will be the most low-maintenance.


The way that septic tanks and sewage treatment plants work is related, but certainly not identical. Both collect waste in tanks and use biological processes to break it down and purify it – to differing degrees. But while septic tanks require no electricity, treatment plants utilise rotating discs which help break it down even further thanks to aerobic biological digestion.


This means that, although septic tanks are low maintenance as they have no “moving parts” and require no servicing (just one yearly emptying will suffice), they do not break down the waste as efficiently. Treatment plants, by comparison do require some electricity, regular servicing and often a permit from the Environment Agency. Depending on the system, they also need emptying every 3 to 6 months.


Sewage treatment plants are able to render waste 95% clean, while septic tanks can only achieve a maximum of 70%. The cleaned effluent from treatment plants can therefore be safely released into ditches and watercourses, as long as the plant has been approved by the Environment Agency.


If you’re looking for a waste disposal system for a larger, busier property or premises, you’ll typically find that treatment plants are much more suitable for your needs. They are able to handle more waste, more efficiently. For smaller properties, however, a septic tank provides a more low-maintenance option which may prove more convenient, with no need for electricity or permits.

From advice and installation, to routine maintenance and emergency repairs, the Drain Doctor team in North Wales and Chester are your local waste disposal experts. Whether you require high pressure jetting to remove clogging, or CCTV drain surveys to identify leaks and blockages, we’re ready to help. Get in touch today on 01352 360 099.

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