Diamond Sewage Treatment Plant

We have a wide range of options available with the Diamond 6 being our most popular sewage treatment plant. Read more about the Diamond 6.

The Diamond Range

From start to finish we have everything you need in a sewage treatment system. If it is determined that the treated effluent needs to be pumped, we can provide a suitable pump station. The Diamond is suitable for 6-55 people and is designed with innovative features ensuring a reliable and effective means of treating effluent from properties not connected to mains drainage. Read more about the full Diamond range available.

The Diamond Range

From start to finish we have everything you need in a sewage treatment system. If it is determined that the treated effluent needs to be pumped, we can provide a suitable pump station. The Diamond is suitable for 6-55 people and is designed with innovative features ensuring a reliable and effective means of treating effluent from properties not connected to mains drainage. Read more about the full Diamond range available.

Table of Contents

What are our customers saying?

"Great company with a friendly and super helpful team. Very clever treatment plant - great system. I highly recommend this company."
Adrian Billing
5 Star Google Review

We are one of the most highly reviewed UK company in off-mains drainage. Read our more than 65 positive reviews.

Why Use The Diamond 6?

Why Use The Diamond 6?

Diamond 6

Best seller sewage treatment plantDiamond 6 Sewage treatment plant

No Odours

It does not require primary settlement tank of sewage where odours can occur.

 

High Performance

Process performance guaranteed for lifetime of the plant. (All units come with a 25 year tank warranty, 2 year blower warranty and a lifetime process warranty.)

Efficient, continuous bacterial digestion process means the plant will continue to perform.

 

Peace Of Mind

Simple design, reliable operation, minimal maintenance mean low running costs.

Fantastic Value For Money

A small air blower means low running costs.

Alarm Beacon Fitted

Unlike other units that charge extra for a warning beacon. The DIAMOND 6 comes complete with two warning beacons fitted to the all weather, air blower kiosk. One beacon alerts to the failure of the blower and another to a high water level so you will always be in control of the situation.

Innovative Features

The Diamond sewage treatment plants are designed with innovative features ensuring a reliable and effective means of treating effluent from properties not connected to mains drainage.

The unit is upside down waiting for installation.

Replacing the dirt after installation.

Once installed, the site is left clean and the unit cover is flush with the ground. The diamond cover and kiosk are green for better camoflauge.

The DIAMOND 6 (our biggest seller) sewage treatment plant is designed with innovative features ensuring a reliable and effective means of treating effluent from properties not connected to mains drainage.

The sewage treatment plant is CE marked and has been tested in accordance with EN12566-3 making it fully compliant with UK building regulations, always make sure your new packaged sewage treatment plant has the CE marking.

The invert level is ideal for new builds and the replacement of existing tanks. The compact design of the units reduces installation and handling costs compared with other plants.

In Domestic applications serving population equivalents of up to 6 people.

The Diamond Range

Available with gravity and pumped outlets to suit all site appliactions.

Diamond DMS range 1 up to 20 occupancy equivalent

Diamond DMC range 21 up to 55 occupancy equivalent

Why Use The Diamond Sewage Treatment Plant?

Designed with innovative features

This ensures a reliable and effective means ot treating effluent.

No odours

Does not require primary settlement tank of sewage where odours can occur.

Process performance guaranteed for lifetime of the plant

All units come with a 25 year tank warranty, 2 year blower warranty and a lifetime process warranty.

Efficient, continuous bacterial digestion process means the plant will continue to perform.

Peace of mind

Simple design, reliable operation, minimal maintenance mean low running costs. And no moving parts in the unit.

The units can be extended up to 1000mm at the factory giving much deeper inlet depths

   

Extensions of up to 460mm can easily added on site for the Diamonds 6, 11, 15 and 20

   

Fantastic value for money

Small air blower means low running costs.

Alarm beacons fitted

Unlike other units that charge extra for a warning beacon. The DIAMOND Range comes complete with two warning beacons fitted to the all weather, air blower kiosk. One beacon alerts to the failure of the blower and another to a high water level, so you will always be in control of the situation.

How Does The Diamond work?

How Does It Work?

Diamond Sewage treatment plant
1

The waste water flows into the main tank and enters directly into the bio-chamber.

The bio-chamber is a zone where the solids circulate continuously; this is achieved by air rather than mechanical or electrical parts inside the tank.

Diamond sewage treatment plant how it works
2

The draft tube enables the solids to be drawn back up into the central aeration chamber and recirculated through the treatment process.

diamond sewage treatment plant how it works
3

The treated liquid then exits through the dip pipe and is discharged safely into the environment, meeting the required consent standard.

Customer Testimonial

Another Customer Perspective

Allerton installs sewage treatment plant and septic tank conversions
"Living close to one of Hampshire's best chalk stream rivers, having the right treatment plant that is compliant and meets with the EA's stringent regulations is a necessity. Our old cesspit did not meet with the latest regulations so when we looked into changing to a sewage treatment plant Allerton gave us the reassurance and expert knowledge that we needed. The treatment plant has been installed for over a year now and we have just had our annual service. The team at Allerton are all knowledgeable, professional, helpful and courteous when ever I have needed to contact them, nothing is too much trouble. I would recommend the company and specially if you live close to a river where specialist advice is needed when considering the options of changing from a septic tank arrangement to a compliant treatment plant."
Nigel Sellers
5-Star Google Review
Dimensions

Diamond Units Dimensions

Diamond Sewage treatment unit diagram
Population Equivalent or PE
6
11
15
20
Outside Diameter A
1.850m
2.070m
2.070m
2.070m
Total Height D
2.340m
2.620m
2.810m
2.810m
Inlet Invert Depth
630mm
760mm
780mm
780mm
Population Equivalent or PE
27
35
45
55
Outside Diameter A
3.300m
3.300m
3.300m
3.300m
Total Height D
3.350m
3.350m
3.720m
3.720m
Inlet Invert Depth
570mm
570mm
580mm
580mm

Outlet Invert Depths are 100mm below the Inlet Pipe on all units.

All these units can be made with deeper inlets at the factory, adding 300, 600, or 1000 mm

The smaller units also have the option of an extension to the turret up to 460mm with or without the factory extension!

About The Population Equivalent

At Allerton we use a calculation for all of our units which is based on British Water guidelines to determine the appropriate size of the unit for the property. The calculation is known as the Population Equivalent (Pe) and it is a rating system that allows information to be comparable between different makes and models of units.

Learn more about sewage treatment

Converting horrible sewage into relatively clean water and using nature to do it seems like a miracle at times. To do it is not so easy though. That is the constant challenge.

If there is excessive use of chemicals, then the bacteria are killed. We need the aerobic bacteria to break down not just the organic matter, but the chemicals as well.

We use bleach and other agents for cleaning the house and chemicals on our hair and bodies. We use chemicals to sterilise our hands. We use all sorts of powerful agents in the kitchen sink. All this has to be neutralise by our friendly bacteria. If too much chemical is used, then they can’t do the job properly.
 
Oil and grease suffocate the aerobic bacteria, allowing the anaerobic bacteria to make the whole lot septic again. Putting spent oil into a bottle is better than down the sink.
 
So, everything is permitted but in moderation!

At Allerton, we have units that we still service and they are 25 years old and going strong.

Klargester are even older!
 
They are not made for a limited life as white furniture is. They do need to be maintained though. Fortunately there are no moving parts in the WPL units.  The diamond Sewage Treatment Plant relies on a blower and when we service the unit we make sure the blower is good for another year at least. We are constantly refurbishingf and replacing them so as to keep the m working constantly  I cannot think of anything else that lasts  as long 

This is a peice of kit which converts raw sewage to clean water. Not clean enough to drink of course as it can still carry E. coli and other pathogens.

It is high in nitrates and phosphate. I should not be sprayed onto plants but can be used as underground irrigation. Roots have the ability to take what they want and to leave the pathogens in the ground.

Sludge is the solids that collect in a septic tank or sewage treatment plant and it needs to be removed to be dealt with by the Water Authorities.

Get it serviced properly. Check that it is not being overloaded above what it was designed for.

For Diamond units, every 3 to 5 years.

WPL Diamond Brochure
WPL Diamond Brochure
Read the WPL Diamond Specification Documentation
Why Allerton?

Why Allerton?

Qualified

All units come with a 25 year tank warranty, 2 year blower warranty and a lifetime process warranty. Allerton offer servicing of the units and other manufacturers’ units so you can always rest assured your treatment plant is receiving the best care.

Value for Money

We offer a free initial on-site consultation for installations within a reasonable distance from Sleaford. We keep our customers in mind when it comes to pricing. We have saved our customers hundreds of pounds over the years by our considered overview. We can do the same for you! Speak to us for a quote!

Friendly

Allerton offers a unique level of service drawing on 50 years of experience we can help with sizing your treatment plant, installation advice and offer a full installation service.

Ready to arrange an appointment?

Contact our office to arrange a visit. Don’t hesitate to talk to us if you have any questions or concerns.

Google Reviews
Carrie ArmitageCarrie Armitage
05:11 28 Aug 24
Allerton's work installing a new domestic sewage treatment plant was first rate. From the initial visit and quote through to the installation everything was prompt, efficient, friendly and lived up to all promises and expectations. The installation team were great to work with, and despite some interesting old drainage issues when excavating the new location and decommissioning the old septic tank, they maintained their good humour and professionalism throughout. I can highly recommend their services. Thank you.
Lisa DavidsonLisa Davidson
05:27 23 Aug 24
Excellent system and the engineer (Dayton) who carried out our annual service recently is clearly very skilled, taking the time to explain things to us and ensuring the septic tank was working correctly, he also enjoys his job which is refreshing to see. The tank still doesn't need emptying after 3 years, very satisfied!
mark quigleymark quigley
10:46 16 Aug 24
Excellent service, great communication and lovely people to deal with.I first wrote this review 3 years ago and they have consistently delivered excellent service since then. Very friendly and professional
Malcolm HarringtonMalcolm Harrington
16:36 02 Aug 24
The Allerton team were excellent. Their work was excellent and their great attitude a credit to them and Allerton.I recommend them highly.
Catherine WhitallCatherine Whitall
15:01 26 Jul 24
Many thanks to Allerton Bradley and especially Jason, Chris, James, Aaron and the team for a top rate service from start to finish. Had a new Diamond DMS3 water treatment plant installed to replace our old septic tank. Extremely professional installation, great communication throughout from the guys on site and the office, tidy, punctual and a fantastic end result. I would say I'm not the easiest to work for, have very high standards, know exactly the job i want done, do not employ many companies as prefer to carry out most jobs myself, however it was a pleasure having these guys on site. Would not hesitate to recommend. Oh and its great to be able to use the loo's etc whenever needed rather than going to the local garden center to use their facilities!!! Many Thanks, Graham & Catherine
Shelley WilliamsShelley Williams
07:14 01 May 24
Cannot recommend Allertons enough! Excellent service with speedy attendance by an engineer and the problem of a faulty timer was resolved without being too costly! Will definitely be saving their contact number on speed dial!
Paul ScottPaul Scott
15:20 22 Apr 24
We have used Allerton to maintain our household pump system for several years. Always found their staff pleasant and helpful. Last weekend a fault developed which we reported on the Monday morning. By Monday afternoon they had called, identified the fault, offered advice, made the repair and everything left tidy and all with a smile.
Cherie PearsonCherie Pearson
16:12 16 Apr 24
Great service, good to receive email reminder when service is due!Very pleasant person arrived promptly to do the service.
harriette Bradleyharriette Bradley
15:44 01 Apr 24
Fantastic service from Allerton. Chris was brilliant! He was punctual, polite and professional. The finish was outstanding. We are so pleased with the result. Would definitely recommend Allerton and Chris. Thank you so much.
Nigel SellersNigel Sellers
10:40 12 Jan 24
Living close to one of Hampshire's best chalk stream rivers, having the right treatment plant that is compliant and meets with the EA's stringent regulations is a necessity. Our old cesspit did not meet with the latest regulations so when we looked into changing to a sewage treatment plant Allerton gave us the reassurance and expert knowledge that we needed. The treatment plant has been installed for over a year now and we have just had our annual service. The team at Allerton are all knowledgeable, professional, helpful and courteous when ever I have needed to contact them, nothing is too much trouble. I would recommend the company and specially if you live close to a river where specialist advice is needed when considering the options of changing from a septic tank arrangement to a compliant treatment plant.
David Le SueurDavid Le Sueur
14:17 11 Jan 24
Alerton is a reliable company that thrives on clear customer contact, providing us with a no nonsense practical service that is invaluable and most necessary.Allerton personnel are pleasant, informed and helpful. We have used the company for years and intend to stay with them.Thank you Allerton for your immaculate service.
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