Sewage. Sorted.
Specialists in Sewage Treatment Systems, Pump Stations, and Septic Tank Conversions
Allerton are the premier off-mains drainage company covering sales, servicing, commissioning and repairs of all types of sewage systems.
James Brown12/03/2025Trustindex verifies that the original source of the review is Google. Excellent service from these guys, reasonably priced too. Thanks Eira Griffiths10/03/2025Trustindex verifies that the original source of the review is Google. Used Allerton's for nine years. Apart from annual service of the pump also had a new pump and guide rails. Always turn up and provide what we consider to be excellent service. Previous owners never had pump serviced and the installer didn't want to know when asked about servicing. Luck to have found Allerton's Martyn Malcomson01/03/2025Trustindex verifies that the original source of the review is Google. Excellent service from Allertons when my Consep failed to pump out. Called them just before closing on the Thursday, their engineer was with me by 8am the next day. The problem was quickly resolved and I was given advice on what to do if the problem re-occurred. mike wentworth24/02/2025Trustindex verifies that the original source of the review is Google. As a customer for almost 20 years I am pleased to recommend Allertons for their efficient professional service; their work technicians have always proved helpful as was Zak who is the most recent. MARY HUGHES21/02/2025Trustindex verifies that the original source of the review is Google. I would like to say a huge thank you to Allerton Bradley. I had a survey done on my septic tank by them this week. Having been really stressed about my house move, I booked the survey. Allerton Bradley were recommended by one of my neighbours. The appointment was confirmed and took place within a couple of days of me emailing my request. James, the engineer came out and was incredibly courteous and professional. Also knowledgeable, most informative and reassuring. There was a comprehensive report which I received within 2 days of the survey. I thoroughly recommend this company and have indeed recommended them already to all my neighbours and friends who have septic tanks. Thank you to all at Allerton. John Lavender05/02/2025Trustindex verifies that the original source of the review is Google. Efficient, pleasant and polite, service completed and area left clean and tidy Nicolas Warren05/02/2025Trustindex verifies that the original source of the review is Google. Sewage Treatment Plants are a very important part of the home and we wouldn’t trust ours to anybody else other than Allerton. They installed the system many years ago and have maintained it ever since. They are professional, knowledgeable and always courteous. They always go out of their way to help, going the extra mile every time. I can’t recommend Allerton highly enough. In fact on our recommendation, our next door neighbours have installed an Allerton system too and are as happy with it and the service they’ve received as we have been. Annie Flavell28/01/2025Trustindex verifies that the original source of the review is Google. Allerton Bradley installed a treatment plant into our existing septic tank in 2020. Until then it had proved very problematic. Since then we have never had any problem with it, and in a couple of the years since have not had to have it emptied either. They are always friendly and approachable and very responsive. Very happy to have chosen them. Nick Williams09/01/2025Trustindex verifies that the original source of the review is Google. Excellent company to deal with. Knowledgeable and great people. James who did the survey and Aaron who organised it. Very pleased that I chose them. Higfhly recommended.
Drainage Problems? We can help!
The separation and treatment of our waste is one of the most important advancements in human history and today our techniques are quite sophisticated. At Allerton, we install and service many sewage treatment systems and are equipped to handle systems manufactured from any company. Whether you want to make a house purchase or sale and need to make the sewage system compliant with the Binding Rules from 2020, or you simply have a clogged drain, we are here for you. We also give free advice in person or over the phone. If you are off-mains, we can solve all of your drainage problems, big or small.
We offer a free site visit within our service area, so contact us today!
We are available for drain unblocking. Call Allerton now 0800 328 5492
What are our customers saying?
We are one of the most highly reviewed UK company in off-mains drainage. Read more testimonials on our reviews page!

Servicing and Maintenance
We are experts in servicing and maintenance, and we service any off-mains sewage treatment system.
Find the option that is most relevant to you in the menu below.
Contact us and we will be happy to make a site visit free of charge. Or you can simply discuss issues with any of our knowledgeable staff in the office.
Products We Service
What We Do
The Diamond Range
We have sewage treatment options to suit any size property. The Diamond 6 is our most popular treatment plant for the average household.
Do you have a blocked drain?
No job is too big or too small. We carry all the tools necessary on a job so we can fix your problem right away. We are experts in drainage and here to help.The Allerton Ground Water Tube (AGWT)
The ideal solution for measuring your soakaway (drainage field) water levels. Buy yours today!
The Allerton ConSept is the ideal solution for your Septic Tank Conversion.
The Allerton ConSept will convert your existing septic tank or cesspool into a fully functional sewage treatment system producing a final effluent that can be discharged into a watercourse or soakaway.¹
¹Discharge to watercourse or soakaway is subject to consent from the relevant authorities.
Why use the Allerton ConSept?
- The Allerton ConSept utilises your existing septic tank so there’s no need for heavy diggers and new units. Plus, it’s quick to install which saves you time, money and disruption.
- No moving parts inside the tank.
- Installation within your existing septic tank means the Allerton ConSept cannot be seen or heard. However, the air blower remains outside the septic tank for easy maintenance.
- Maintains water at correct level, keeping drains clear right up to the house.
- Manufactured using high grade composite materials and non-ferrous components means the Allerton ConSept does not corrode. This results in a long and trouble free life.
- Aerobic process reducing smell and odours.
- Low maintenance costs – Servicing once a year, desludging and emptying once every two years, Installation, Septic Tank Conversion Unit Servicing and Maintenance available.
- Discharge to watercourse with permissions or to a soakaway.
- Installation and commissioning by our British Water Accredited engineers included in package.
How does the Allerton ConSept Work?
ConSept illustration is not drawn to scale.
The Allerton ConSept will convert your existing septic tank or cesspool into a fully functional Sewage Treatment Plant producing a final effluent that can be discharged into a water course or soakaway. (We can help with the Environment Agency permit)
The raw sewage enters the septic tank which will become the aeration zone. Air blown from the Blower causes agitation in this area and breaks ups solids.
The Allerton ConSept is an aerobic treatment system and the bubbling air encourages the growth of aerobic bacteria. This is a huge improvement on traditional septic tanks which are anaerobic.
The space in the Allerton ConSept acts as a settlement zone, allowing fine solids to settle out. The treated effluent is lifted to the shallow sample chamber by syphonic action. From here the water can directly go to a water course, providing you have a permit from the environment agency.
Alternatively, the water can go into the existing soakaway as it now has a head of water to push it along the pipe and upwards into the topsoil. From here it finds its way sideways and downwards.
The plug in the outlet pipe prevents water in the ground getting into the septic tank and manholes near the house. It separates the house from any groundwater so your drains will remain clear.
Allerton Servicing and Maintenance
Regular servicing and maintenance is recommended to ensure long service life of your Allerton ConSept. We recommend servicing once a year and desludging and emptying once every two years. Allerton provide a full servicing contract and maintenance contract ensuring the following:
- Checking Pipework is in good working condition, including valves etc.
- Diaphragms and filters checked and/or replaced
- Replacement of perishable parts as required, blowers checked and tested under working conditions
- Deciding whether units require desludging or cleaning.
The Allerton ConSept comes with a 2 year warranty on all working parts.
Q: What is a ConSept?
A: A conversion of a septic tank, a cesspool, a well, or some other underground tank to a sewage treatment plant.
Q: Can I outfall ConSept treated water to a ditch?
A: YES, but only if you obtain a permit from the EA. Though Allerton will help you with it. Contact us for more details.
Q: If my septic tank goes into a soakaway, do I need permission to install a ConSept?
A: NO. But you do if you decide to outfall it into a ditch.
More answers on our FAQ page
Are you compliant with the General Binding Rules from 2020?
On a budget but need to comply with the binding rules? A septic tank conversion is a budget-friendly way to upgrade your system without installing a new sewage treatment system.
About Allerton
History of Allerton
In 2024, we’re celebrating 50 years in drainage. Starting out as Allerton Contracting Co Ltd in 1974 and later became Allerton Bradley Ltd in 2019. Read all about our company on our About Allerton page.
Our experience in land drainage has paved the way for us to develop sophisticated new techniques and systems for sewage treatment through the years. Customer experience is at the heart of everything we do.
We are experts in installations, servicing, and maintenance for sewage treatment plant, pump stations and septic tank conversions.