Sewage treatment plants

What are sewage treatment plants?

Sewage treatment plants, also known as wastewater treatment plants, offer a cost-effective and eco-friendly way of treating wastewater where there’s no mains sewer connection by collecting, processing and disposing of sewage. They come in a range of sizes and are suitable for most sites, from small domestic properties to expansive commercial developments.

How does a sewage treatment plant work?

Sewage treatment plants collect wastewater from toilets, washing machines, baths, sinks and showers, which drains into the plant via pipes. The treatment plant then settles the sewage, separating out large solids. It is then aerated with an aerobic bacteria, fully treating it before finally being settled again prior to discharge. A sewage treatment plant produces cleaner and more environmentally-friendly “effluent”, (the term for treated water) than septic tanks so that it can be discharged directly into a ditch, stream or other waterways.

Domestic off-mains drainage

About our domestic sewage treatment plant models


Our domestic sewage treatment plants are the most efficient, dependable and cost-effective solutions available.


The standard model has now been modified to make it more reliable than ever, while the ultra model has new, innovative features to reduce noise, increase efficiency and improve effluent quality.

High performance wastewater solutions


Both of our sewage treatment plant models offer world-class performance, are tested and approved to BSEN12566-3/A1:2009 as standard and have been proven to produce more purified effluent than competitor products.


Our sewage treatment plants are available in a range of sizes, from 4 to 50 PE with ultra, standard and shallow versions of all sizes.


Every sewage treatment plant we offer has a large choice of ancillaries, so we can specify a solution to suit your site and budget.

Benefits of our domestic sewage treatment plants

  • Easy installation thanks to “forsheda seal” inlet and outlet
  • Near silent operation
  • Minimal running, maintenance and service costs
  • Internal or external compressor housing options to suit your site
  • Safe electrical connection
  • Easily removable pressure pipe to transport air diffuser line
  • No flooding or leaking due to high spec bio-media and membrane diffusers
  • No blockages, strong circulation and high effluent quality due to large sludge return
  • 40% less solids and longer drainage field life compared to other models
  • Robust – heavy duty lid and frame adds strength and durability
  • Safe and secure site handling with integral lifting eyes
  • No rolling and easy transportation thanks to stabilising feet
  • Can be easily and safely anchored into granular or concrete surrounds down to unique “keying-in” lip
  • Shallow models available – only 1.6m high, compared to 2.3m height of other models – makes for easier and safer installation

Why choose S&S Site Services’ sewage treatment plants?

Easy to install

100% reliable

97% of pollutants removed

Cost-effective to operate and maintain

Technical support from our skilled service engineers

How our sewage treatment plants work in six stages

Wastewater drains into primary settlement chamber

Anaerobic digestion breaks
down solids

Clarified water passes into second aeration chamber

Aerobic bacteria removes dissolved constituents and fully treats water

Treated effluent and “sloughed off” bacteria flows to final settlement chamber

Final effluent discharged to drainage field or watercourse via filter

Commercial sewage treatment plants

Biological processing for off-mains wastewater on commercial sites.


About our commercial sewage treatment plants


Our commercial sewage treatment systems are suitable for treating off-mains wastewater on large scale residential, commercial, industrial and leisure sites.


With sizes ranging from 50 to 300+ PE, we can specify a solution to suit all commercial developments.


The Submerged Aeration Filtration system featured in our commercial sewage treatment plants makes it a cost-effective, highly effcient and low maintenance solution.

Benefits of a sewage treatment plant

Modern sewage treatment plants offer a multitude of benefits to users:

Save money Sewage treatment plants are a cost-effective way of treating and disposing of wastewater, and once you have one, you’ll have no sewager bills to pay either. They can last for up to 15 years if they’re installed and maintained correctly.

Suitable for most off-mains sites We can install modern wastewater treatment plants on most domestic and commercial sites, even in the smallest and most challenging locations. All of our service engineers are fully trained to work in confined spaces.

Minimal maintenance Most modern sewage treatment plants only require maintenance inspections every one or two years, so they’re low maintenance and cheap to run.

Flow treatment For sites with fluctuating loads - like caravan parks and hotels - we can design plants with flow balancing to spread the load over a 24-hour period.

High performance Sewage treatment plants perform highly effectively, breaking down solids quickly and experiencing minimal blockages.

No bad smells Thankfully, modern sewage treatment plants don’t emit any nasty odours, compared to older equipment.

Safer for the environment By treating water safely, sewage treatment plants banish bacteria and dangerous organisms from sewage, removing harmful contaminants through a filtering process before it reaches the ground. Sewage treatment plants are therefore kind to the environment and protect animals and plants from contamination.

We work with the leading manufacturers of sewage treatment plants, so we will always specify a high performance, durable and cost-effective solution, whatever your water situation. Our complete sewage service covers supply, installation and maintenance, or you can select a supply-only or one-off maintenance service if you prefer.


We are confident in ensuring we deliver a service that lives up to expectation and strive to provide a successful and on-going relationship with all our clients.