DMS (1 – 20 occupancy equivalent)

Discover the WPL Diamond DMS

Discreet wastewater treatment


Small tank, big results!

Backed by 25 years tank warranty 

If your property is not connected to mains sewerage, your wastewater can be treated by our discreet below ground WPL Diamond DMS package wastewater treatment range.

This is a small and compact wastewater treatment plant designed for properties that house 1 person or up to 20 (people) occupancy equivalent; ideal for new builds and replacement of existing septic tank systems and package sewage treatment plants.

No need for chemicals, allowing final effluent to be safely discharged to a soakaway or watercourse.

Our WPL Diamond is better designed for modern day living than a septic tank system; with a faster process and a more environmentally friendly end result, it is the ideal replacement solution.

Typical domestic uses

Single and small group of houses

Agricultural buildings to dwellings such as barn coversions

Replacement of septic tank systems

Typical commercial uses

Glamping sites and Bed and breakfasts

Small commercial buildings and retail such as farm shops

Replacement of septic tank systems

Key features

25 years warranty*

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

Longer emptying cycle*

Up to 3 years desludge – due to our highly efficient aeration process which breaks down organic matter at a reduced sludge rate resulting in longer emptying cycles of up to three years.

Low user maintenance

No internal electrical or mechanical moving parts inside the tank, offering minimal maintenance compared to other processes on the market which are prone to breaking down.

No odours*

The WPL Diamond wastewater treatment range is odourless so you won’t even know it’s there!


No hidden costs

The standard package includes a WPL Diamond DMS tank, WPL kiosk, alarm beacon, blowers and 10 metres air hose. Additional extras are available.

Simple installation

Compact in design, keeping the excavation to a minimum and the installation simple, with little disruption.

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

Easy on the eye and the landscape

Our WPL Diamond DMS is entirely underground, boasting the flushest lid on the market and ensuring minimal visual impact to your beautiful garden or surrounding landscape.

Fully compliant

The 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.

Kind to the environment

Unlike other tanks on the market, our WPL Diamond has no need for additional chemicals, to reduce our environmental impact.

Environment Agency approved

The liquid matter (effluent) discharged by our WPL Diamond range is fully compliant with the regulations set by Environment Agency (EA) and exceeds normal consent standards.

WPL Diamond Process

Our WPL Diamond has the advantage of a high quality process for wastewater treatment; in a compact single tank which is easy to install and maintain.



Ideal septic tank replacement

Homeowners with septic tanks that discharge directly into the surface water will now need
to consider the option of replacing with a packaged wastewater treatment plant,
when selling a property or upgrading an ‘end of life’ septic tank.

Unlike the traditional septic tanks, the modern packaged wastewater (sewage) treatment plants such as a WPL Diamond
are designed with an aerated process for todays’ increased volume of water usage in everyday life.


Looking for technical information?

Technical zone

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, which means the WPL Diamond has been assessed against Building Regulation requirements and can be installed without the need to have it signed off again by building control.

Part H2 for building regulations

The WPL Diamond is 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 9001

ISO 9001 – 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.

Accredited ISO 14001

ISO 14001 – Recognised for our Environmental Management System compliance.

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.


Investors in People

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

Accredited CPD Seminars

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

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.