Sewage Treatment Plants

Innovative Design - Smart & Simple Sewage Treatment Plants

Sewage treatment plants are designed to remove bacteria and other contaminants from waste water. The method of treatment can be physical, biological or chemical or a mixture of all three, depending upon the sophistication of the system in question. The aim of the treatment plant is to produce an environmentally safe effluent and a solid waste that can be disposed of or re-utilised as fertiliser.

We sell a wide range of commercial and domestic sewage treatment plants from market-leading brand Graf. Sewage Treatment Plants are used in properties that are not connected to a mains drainage system. They collect effluent from household foul drainage systems (WC's, Kitchens, Bathrooms etc) and usually separate it into two chambers, solid and liquid.

How Sewage Treatment Plants Work

The liquid (effluent chamber) is treated using a variety of mechanical and/or chemical processes depending upon the specific system, stimulating helpful bacteria which "clean" the effluent. The resultant "cleaned" liquid, which is generally around 95% clean water, can then be returned to a ditch or natural watercourse. The remaining sludge is removed from the solid chamber by specialist companies on a regular basis as required.

Does a sewage treatment plant need a soakaway?

Although soakaway crates are innovative and effective for discharging stormwater and rainwater back into the ground, we would not recommend using soakaway crates alongside your sewage treatment plant or septic tank – doing so would actually be illegal.

The crates are not designed for use with untreated or any form of wastewater, and neither would we encourage the release of this water back into such concentrated areas of the ground.

Untreated water can be foul smelling and hazardous, so the release of this through soakaway crates back into public drinking water boreholes will only cause further trouble.

Do sewage treatment plants need emptying?

Although sewage treatment plants can deal with more wastewater than septic tanks, they will still need occasional emptying.

Many manufacturers recommend annual emptying due to the build up of sludge within the system. Sludge is a build-up of solids within the tank, and must be removed periodically, as too much of this contamination will result in unclean water, defeating the purpose of the sewage treatment plant. If you’re unsure how often to empty your treatment plant, you should get in touch with your supplier or retailer, as some lower budget options may need more frequent emptying.

What Are The Benefits Of ONE2CLEAN Treatment Plants?


Through One2Clean technology, any wastewater that enters the tank is immediately activated with oxygen. At the end of the sewage treatment process, the tank produces clear, odourless water that is ready to be extracted via a soakaway or underground pipe.


One2Clean tanks achieve sustainable discharge values with an efficiency factor of up to 99%. This future proofs the system from the inevitability of legal sustainable drainage requirements becoming stricter.

Environmentally Friendly

Due to their light weight and simple construction, One2Clean tanks are easy to transport and feature just one pumping process, whereas most sewage treatment plants typically feature three. This significantly reduces energy consumption and running costs. Each tank also includes an energy-optimised membrane compressor and an economical motor valve. The tanks are stored and delivered in two half shelves which can easily be stacked on top of one another, reducing freight costs by 80%.

Easy Installation & Maintenance

The light weight of One2Clean tanks makes them easy to transport and install along with the fact that only one tank and chamber are required. Technology is only used where necessary, and the space required for a tank starts at only 4m2 for a 5 person unit. The tank can be mounted in groundwater and the telescoping and tilting lid is easy to fit flushed to the surrounding ground surface. Maintenance is simple and is performed via an integrated self-cleaning sampling container.

Long Lasting

Our sewage treatment plants come with a 15 year warranty on the reservoirs and 3 years on the technology, but both parts can easily last in excess of their warranties.

Sizing of Sewage Treatment Plants

STP's are sized on the amount of persons living in the property or properties that use the STP. Often the treatment plant will be connected to a number of common properties, so we currently offer systems that are up to 18 person occupancy.

Pumped and Gravity Fed

Most STP's have either a gravity fed or pumped option for disposing of the cleaned water. With our Graf and Clearwater Sewage Treatment Plants, an optional pump can be purchased for use with the standard gravity outlet plant. With the WPL tanks there are individual tank options for either pumped or gravity fed.


For details on delivery and returns of this product range, please consult the delivery & returns tab below.

Please contact us if you require further details on any of these products.

Please note - Our Sewage Treatment Plants Do Not Qualify For Our Spend & Save Volume Discounts

If you don't have offload facilities onsite, please contact us so we can arrange for a suitable vehicle to be sent (this may incur an extra cost).

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11 Items

  1. Graf One 2 Clean Sewage Treatment Plant Gravity Fed - 3750 Litre For 5 Persons

    Please allow 2-3 weeks for delivery

    1. Code G50000
    2. Brand Graf
    3. Treatment Plants Capacity 3750 Litres (5 Persons)
    £1,906.99 £2,288.39
  2. Graf One 2 Clean Sewage Treatment Plant Gravity Fed - 4800 Litre For 7 Persons

    Please allow 2-3 weeks for delivery

    1. Code G50002
    2. Brand Graf
    3. Treatment Plants Capacity 4800 Litres (7 Persons)
    £2,168.05 £2,601.66
  3. Graf One 2 Clean Sewage Treatment Plant Gravity Fed - 6500 Litre For 9 Persons

    Please allow 2-3 weeks for delivery

    1. Code G50004
    2. Brand Graf
    3. Treatment Plants Capacity 6500 Litres (9 Persons)
    £2,362.56 £2,835.07
  4. Graf One 2 Clean Sewage Treatment Plant Gravity Fed - 2 x 3750 Litre For 10 Persons

    Please allow 2-3 weeks for delivery

    1. Code G50006
    2. Brand Graf
    3. Treatment Plants Capacity 2 x 3750 Litres (10 Persons)
    £2,686.32 £3,223.58
  5. Graf One 2 Clean Sewage Treatment Plant Gravity Fed - 2 x 4800 Litre For 14 Persons

    Please allow 2-3 weeks for delivery

    1. Code G50008
    2. Brand Graf
    3. Treatment Plants Capacity 2 x 4800 Litres (14 Persons)
    £3,307.10 £3,968.52
  6. Graf One 2 Clean Sewage Treatment Plant Gravity Fed - 2 x 6500 Litre For 18 Persons

    Please allow 2-3 weeks for delivery

    1. Code G50010
    2. Brand Graf
    3. Treatment Plants Capacity 2 x 6500 Litres (18 Persons)
    £3,498.63 £4,198.36
  7. Graf Sahpir Sewage Treatment Plant Pumped Outlet
    Out of Stock

    This is a bespoke product, please get in contact with us for more details.

    1. Code SAPHIR600
    2. Brand Graf
    £0.01 £0.01
  8. Graf Turret Extension Piece
    1. Code 371003
    2. Brand Graf
    £172.05 £206.46
  9. Sampling & Distribution Chamber - 300mm Diameter Accesso with 110mm or 160mm Inlet / Outlet & 110mm Side Distribution Channels with Lid

    Please allow 5-7 working days for delivery

    1. Code ASDC30015SP
    2. Brand Turtle Enviro
    £245.71 £294.85
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11 Items