Sewage Treatment Plant Installation

Sewage Treatment Plants treat sewage to a standard that is suitable for discharge into a ditch, stream or river without the need for extensive soakaways / drainage fields.

WCI are approved installers for a wide range of sewage treatment plant manufacturer.  Our professional engineers are experienced in the operation and maintenance of treatment plants meaning our installations are always meet your requirements.

There are many sewage treatment systems available including package sewage treatment plants and bespoke-built schemes for larger applications. Most sewage treatment plants are designed for human sewage, normally termed ‘domestic sewage or wastewater’. Domestic sewage includes waste from kitchens, bathrooms and laundries and not just toilets.

In England and Wales, planning regulations stipulate that a package sewage treatment plant is to be preferred over a septic tank. However, discharges from sewage treatment plants may still require an Environment Agency permit irrespective of whether they discharge to a watercourse or to ground.

High Quality Installation

WCI has installed thousands of sewage treatment plants from small residential systems to large scale bespoke systems.  Over this time, we have developed a process which ensures that the installation of a new sewage treatment system is stress-free and comprehensive for our clients. 

Our Project Engineers over-see an entire installation from start to finish so our clients have a single point of contact.  Our dedicated groundworkers undertake the physical works sympathetically, safely and with the highest standard of finish. Our dedicated Service Engineers commission every system and provide a Commissioning Certificate which validates manufacturers warranties. And the entire process is supported by our Operations Manager and back-office staff to ensure a smooth and efficient completion to every project.

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Professional Wastewater Engineers

WCI have over 40 years experience in designing and installing wastewater treatment solutions.  We don’t just install the cheapest sewage treatment plant or the one a manufacturer gives us the biggest discount on.

Selecting and installing a sewage treatment plant, even for the smallest property, should take account of a wide range of factors.  Our professional engineers always survey your property to fully understand your needs and budget before recommending a sewage treatment plant that provides value for money and assured compliance and functionality.

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When it comes to sewage treatment, one size certainly does not fit all. There are a wide range of sewage treatment systems available, each catering to different needs and capacities.

WCI are approved installers for many manufacturers of sewage treatment plant including Graf, WPL, Tricel, Klargester, Premiertech Aqua, Harlequin and Marsh Industries.

Sewage Treatment Plants 

Sewage Treatment Plants (STPs) or Package Treatment Plants (PTPs) are compact and efficient systems that treat sewage.  How they do this differs from manufacturer to manufacturer but they all aim to do one thing… treat sewage to a sufficient standard so that it can be discharged into the environment.

Submerged Aeration: Think aquarium.  Submerged Aeration introduces oxygen into the sewage by bubbling enough air through it to promote the growth of beneficial microorganisms that break down contaminants.  Examples include the WPL Diamond or PremierTech ASP.

Sequencing Batch Reactor (SBR): SBR systems also use a compressor to bubble air through liquid sewage.  However, SBR systems treat sewage in batches, allowing for more efficient and controlled treatment processes. 

Rotating Biological Contactors (RBC): RBC systems get oxygen to the microorganisms by using half-submerged rotating discs rather than air compressors.

Passive Aerated Filter: Passive Aerated Filters trickle sewage over a filter open to the atmosphere.  Microorganisms thrive on the filter material and get their oxygen from the atmosphere without needing compressors or motors making passive aerated filters very energy efficient.

Whether it’s a submerged aeration, sequencing batch reactor, RBC or passive aerated filter, WCI will always specify a system which best meets your budget and your requirements.

We take into consideration the required treatment quality, energy consumption, the available space and ground conditions as well as the levels of noise that can be tolerated and the visual impact the system will have.


The selection, installation and operation of sewage treatment plants can be a complex topic.  Here are some of the more common questions we receive about sewage treatment plants.

What is the difference between a septic tank and a sewage treatment plant?

A septic tank is a settlement tank in which raw incoming sewage is retained long enough for suspended solids to settle out as sludges and for liquid organic matter to undergo anaerobic decomposition.

As the sewage settles, a scum forms on top of the tank consisting of fats and soaps, and heavily organic matter settles at the bottom of the tank as sludge. The relatively clear liquid, called septic tank effluent, which lies in between the scum and sludge, leaves the tank and then undergoes secondary treatment in a drainage field.

While there is some anaerobic decomposition in the septic tank, this bacterial action is not efficient enough to fully treat the sewage to a level which is safe to disperse into the ground.  A septic tank alone will only reduce the strength of the incoming sewage by 30-50% under ideal conditions.

Sewage treatment plants treat raw sewage to a much higher standard.  By using a combination of aerobic and anaerobic digestion, raw sewage is treated so that reductions of 90%+ are achieved.  This allows the treated effluent to be discharged in certain circumstances to ditches, streams and rivers.  Septic tanks do not treat to the same standard so much discharge into the ground.

What is the typical cost of installing a sewage treatment plant?

The cost of installing a sewage treatment plant is generally dependent on the size of the property, where the treatment plant will discharge and site conditions like access, soil and topography.

For a single dwelling with reasonable access for large machinery, installing a sewage treatment plant will typically cost between £12,000 and £15,000, assuming a discharge to a nearby stream.

Can I install a sewage treatment plant in my driveway?

Yes. Some, but not all, sewage treatment plants allow for installation in a driveway.  WCI always ensures that the installation is properly designed for the maximum weight of vehicle that might use the driveway.

Are sewage treatment plants noisy?

Most sewage treatment plants use electricity to deliver oxygen to the bacteria that are doing the treatment of sewage.  The method used (see above on different types of treatment plant) generally defines the amount of noise generated.  In most cases, the noise is barely audible but some cheaper treatment plants will make more noise and use more electricity.

It is always wise to talk to the experts about the selection of a sewage treatment plant.  WCI will discuss your needs and recommend a suitable sewage treatment plant to meet these.

Do I need planning permission to install a sewage treatment plant?

In most cases, if you’re replacing an existing septic tank or sewage treatment plant, you don’t need planning permission to install a new sewage treatment plant.  If you are building a new property, you will normally need planning permission for the build as a whole including the drainage systems. 

WCI are drainage experts and can advise on technical and regulatory requirements for your particular circumstances.

Can rainwater drain to my sewage treatment plant?

No. Sewage treatment plants are designed to treat a certain amount of sewage per day.  Rainfall increases the flow to the treatment plant effectively flushing out sewage before it has had time to be adequately treated.

All sewage treatment plant installations should be installed in accordance with Building Regulations.  WCI provides a ‘Design and Build’ service ensuring that your installation both functions correctly and meets the relevant regulations.

Who can commission a sewage treatment plant?

Installation of a sewage treatment plant is not just about digging a hole and putting in a tank.  A properly installed sewage treatment plant should be commissioned by a British Water-accredited Service Engineer who will ensure that all the components of the treatment plant are correctly installed, tested and configured to operate correctly.

WCI’s in-house British Water-accredited Service Engineers commission every sewage treatment plant installed.  This is evidenced by a Commissioning Certificate which validates the manufacturers warranties.

Current & past projects

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A bold new leisure complex comprising hotel, leisure centre and 46 holiday apartments located in an elevated rural position near Torbay, Devon. The Arboreteum, now known as Landal Barton Pines, lies above Paignton near the Devon coast. Originally home to a historic hunting...

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Down Farm is a rural 4 bed domestic property and was served by an historic septic tank and soakaway in neighbouring land and was suffering from surface water intrusion from a nearby yard. The house was unable to be sold. The solution proved to be tricky but fool proof in its...

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The previous treatment plant at Home Farm was a trickle-filter system installed in the 1950s, which had reached the end of its operational life. Since it was first installed the number of holidaymakers using the centre had grown considerably and there had been issues with...

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Keith and Linda - Baghay Cottage

We were very impressed with the WCI installation team, who worked very hard and diligently in the most awful wet conditions to install our new sewage system. The team also did their very best in the pouring rain to ensure that the site was left tidy. Also, over the Xmas holidays, Brad promptly fixed a problem with the pump. Thank you for a job well done.

Emma Sherman - Greengates

We have found the service right from the very first phone call, site visits, detailed quote though to completed job exceptional. The whole team proved to be very knowledgeable in this field and we had full faith the system is the correct one for us. The site was complex and was left in a better site than it started, we can not thank WCI enough and would highly recommend.

Ms G Fraser - The Old Parsonage

I am thrilled with all you did here. The installation of the new drainage system was completed to my total satisfaction. It was a huge job but within a few weeks, there was no visible sign of the movement of heavy machinery or of the temporary disruption to the garden. Your staff were superb and the supervision and support from head office exemplary. I would recommend WCI to other people without hesitation.

Mr Shirley - Chard, Somerset

‘Friendly Professionalism’ must be the bywords for WCI.  Following on from the foul drainage report which fully analysed our sewage treatment issues, an ingenious solution was proposed and adapted, after full consultation on the options open to us.

The installation was done most efficiently and skilfully, and the team were a pleasure to have working here. The WCI Service Team now carries out the annual service of the system. We are very pleased with the service provided by WCI as a ‘one-stop’ solution.

Anthony - Brownings Farm

I must confess that I approached this project with some trepidation! However, the planning, groundworks, spoil disposal, installation and commissioning went like clockwork. On time, on budget and very pleasant people to deal with.

Robert - Higher Moneys Land

We’re really happy with the work and all other interactions, everything has been really professional and prompt from start to finish. The guys have done a really nice job and managed to avoid making a mess even in the wet weather. I’ve been really happy with all communication from everyone, Brad, Naomi and the guys on site kept us up to date with the planning and progress.

Mike - 8 Battleton

Such a pleasure working with WCI.  From initial contact and survey I have rarely met a more professional company that were able to dispel much of the worry of such a large scale operation.  Their communication was second to none every step of the way from office staff to on the ground contact.  Works were professionally and thoroughly investigated and completed in exactly the time they had promised to an incredibly high standard.  Could not recommend this company highly enough for what was initially a daunting project for me.

J Gallop - Jasper Cottage

We have used WCI for very many years. They are a family company and it is family values they show when dealing with their customers. Recently we had to have a new septic tank fitted. This is a big undertaking and, frankly, I was a bit stressed about it. The WCI team were great all the way through the process. They did two site visits and talked us through all the options. They turned up when they said they would, completed the job in the agreed timescale, and charged us as per their quote with no extras. They left the site in tip top condition and checked in to make sure we were happy. Great service and quality, we would not go anywhere else.


Call us on 01984 623404 or click here to let us know about your current project.