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Our 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 WPL 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 WPL Diamond sold, backed up by our recommended list of independent network of experts who can install, service and maintain your plant.

So discreet

Our WPL 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)

WPL is part of WCS Environmental Engineering (WCS Group) – Marlowe’s grouping of water and air industry.

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

Show me the tank

Easy to install…

Easy on the eye and landscape

Our tank is entirely underground with the flushest lid on the market, ensuring minimal visual impact to your beautiful garden or surrounding landscape.

Minimal disruption to your daily life during installation

Our robust tank is compact in design, keeping the excavation to a minimum and the installation simple.

25 years warranty*

The WPL Diamond comes with 25 years tank warranty and a process performance guarantee for the life of the tank. The warranty of the air blower (housed in the kiosk) is 2 years.

Environmentally Compliant

Our high quality WPL Diamond range is CE marked, fully type tested and certificated in accordance with the mandatory European standard BS EN12566-3 2014 for small wastewater treatment systems.  Performance tested at an independent accredited facility in Germany.

*subject to correct installation, consistent influent conditions and regular plant maintenance as per the manufacturers’ instructions.

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WPL Diamond standards

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 WPL 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 WPL 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 – Our mission is to ensure that we enforce standards with our Occupational Health & Safety Management System.

British Water Packaged Treatment Plant (PTP) Focus Group

WPL 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 also a member of British Water Trade Association for the UK Water and Wastewater Industry.



Composites UK

WPL is a member of Composites UK, an accredited trade association for the UK composites industry, promoting the best practice use of composites materials.

Accredited CPD Seminars

WPL presents free accredited CPD seminars on off-mains sewage treatment, delivered virtually or on site at your location of choice.

Investors in People

Investors in People is an internationally recognised accreditation for our standards of better people management.