Diamond Sewage Treatment

Affordable small systems ideal for private individuals

WPL’s Diamond sewage treatment plants (STP) are suitable for single or multi-property installations up to a PE (Population Equivalent) of 20.

There are five models in the range to cater for different Population Equivalents:

  • DMS1   1-3 PE
  • DMS2   1-6 PE
  • DMS3   5-11 PE
  • DMS4   10-15 PE
  • DMS5   14-20 PE


Unlike some other treatment plant technologies, the Diamonds works effectively at maximum PE loadings, therefore, it is not necessary to oversize plants in order to consistently meet the Environment Agency’s Consent to Discharge Standards. To discuss sizing requirements please contact Filta on 01788 550100.

WPL’s Diamond Sewage Treatment Plants – Summary of Advantages

The Diamond STP has some major advantages over competitive plants available for use in the domestic or small commercial sector marketplaces, namely:

  • Low Tankering Costs - Long interval between plants de-sludging (emptying) once every 2-3 years, or longer. This is due to the Diamond’s unique process of treating both the liquid and solids.
  • Low Maintenance Costs - The Diamond has NO media, NO electrics and NO moving parts within the hostile environment of the treatment plant so has low on-going maintenance costs.

How the Diamond Works

The Diamond’s unique internal weir design ensures that solids do not escape with the final effluent into the soakaway or watercourse.

The Diamond’s process relies on gravity then aeration to circulate oxygen to assist the natural biodegrading of the solid matter and fluids. A kiosk housing the compressor with low power consumption (70 up to 270 watts, dependent upon model) is externally mounted to provide aeration to the plant.

The Diamond treats effluent to the 20: 30 mg/l BOD: Suspended Solids Royal Commission standard on a 95%ile basis.

As Diamonds do not have Primary Settlement Tanks (where raw sewage can turn septic after 90 days) they should not produce unpleasant odours (hydrogen sulphide) emanating chiefly from stored solids. Generally, plants do not require venting as the normal route is through the soil vent pipe (SVP) on the building.

Salt-based water softeners should not be used with any sewage treatment plant unless the backwash of concentrated brine solution can be diverted to not discharge into the plant. This backwash gives the live bacteria a toxic shock.

Waste disposal units can be used but they will increase the loading on the plant by 30% and may marginally shorten the period between desludges.

Diamond Sewage Plant Sales

For sizing advice and quotation for your WPL Diamond Sewage Treatment Plant please contact Filta on 01788 550100.

Diamond Sewage Plant Maintenance

The Diamond only needs minimal annual maintenance tasks. These tasks are quick, easy and are not messy, unlike some other plants. Clients may do their own servicing or alternatively, we can provide specialist maintenance (and keep records as required by Environment Agency’s Consent to Discharge) and supervised tankering. 

To discuss the benefits of a maintenance contract for your Diamond Sewage Treatment Plant please contact us on 01788 550100.

Our service is carried out in 3 Stages:

Site Survey

Site Survey

Filta will survey your establishment, to correctly identify your requirements.



Our trained engineers will install a grease management system to suit your needs.



On a regular basis, we will ensure the equipment is working effectively & efficiently.

For more information about our water pumping solutions or to discuss the requirements of your commercial establishment, contact our team on 01788 550100.