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Our Diamond (formerly known as the WPL Diamond) compact package wastewater treatment plant is suitable for domestic and small commercial properties in all ground conditions where mains drainage is unavailable.

So simple

Unlike traditional septic tank systems, modern package wastewater (sewage) treatment plants are better designed for todays’ increased volume of water usage in everyday life. Our Diamond meets this growing demand and has an added advantage of a high quality process for wastewater treatment, in a compact, single tank. Easy to install and maintain, our range offers a longer term cost-saving solution.  

So reliable

We offer you a 25 years tank warranty with each Diamond sold, backed up by our recommended list of independent network of experts who can install, service and maintain your plant.

So discreet

Our Diamond DMS (1 up to 20 people occupancy equivalent) and DMC (21-55 people occupancy equivalent) ranges are compact, odourless and entirely hidden below ground. With the flushest lids on the market, you won’t even know it’s there!

Diamond DMS (1-20 people) Diamond DMC (21-55 people)

The Diamond range is now a part of WCS Environmental Engineering (WCSEE)

WCS Environmental Engineering logo

Image of a WPL-Diamond-small-sewage-wastewater-treatment-plant-for-off-mains-drainage-the-flushest-lid-on-the-market-so-discreet.

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Easy to install…

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The Diamond standard

BS EN 12566-3

CE marked, fully type tested and certificated in accordance with the mandatory European standard BS EN12566-3 2014 for small wastewater treatment systems.


LABC approved

LABC approved England and Wales, the Diamond is designed to be fast tracked through the building regulation process saving you valuable time.

Part H2 for building regulations

Fully compliant in the UK with HM government guidance for Drainage and Waste Disposal, Part H2 for building regulations of wastewater treatment systems.

General binding rules

Meets current legislation for exemption from a permit to discharge by the Environment Agency (EA), England, as per the General Binding Rules document.

British Water Flows and Loads code of practice

Designed using the British Water Flows and Loads code of practice, to ensure correct sized tanks.

UK & European patented

The Diamond is UK and European patented. This means that our design is completely unique. Patent number: GB 250337.

Accredited ISO 14001:2015

ISO 14001:2015 – Recognised for our Environmental Management System compliance.

Accredited ISO 9001:2015

ISO 9001:2015 – Recognised for our Quality Management System requirements for all areas of the business.

Accredited ISO 45001:2018

ISO 45001:2018 – To ensure that we enforce standards with our Occupational Health & Safety Management System.

British Water Packaged Treatment Plant (PTP) Focus Group

Technical Director Andrew Baird has 30 years’ experience in the water and wastewater treatment industry. As a former convenor of British Water’s Package Treatment Plant Focus Group, he has been influential in the development of British and European Standards and continues to promote good practice in design, installation and maintenance of compact treatment technology.

WPL is now a part of WCS Environmental Engineering (WCSEE) who is also a member of British Water Trade Association for the UK Water and Wastewater Industry.