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Clearwater BioAir CW4 Sewage Treatment System (up to 12 person)

£2,483.00
£2,979.60 (inc VAT)
£2,483.00 (exc VAT)

FREE UK 
DELIVERY

CUSTOMER OFFLOADING

BELOW
GROUND

SEWAGE
WATER

Discharge Type
Inlet Invert
Quantity

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Product Description

This product is delivered directly from the supplier, lead times vary.

 

The Clearwater BioAir CW4 Sewage Treatment Plant is a high-performance wastewater treatment system designed for properties with a population equivalent of up to 12 people. Utilising advanced aeration technology, the BioAir CW4 delivers exceptional treatment efficiency, achieving up to 97.5% BOD₅ reduction before discharge. Ideal for larger domestic properties, small commercial premises, and off-mains drainage applications, this system provides reliable and environmentally responsible wastewater treatment.

 

Manufactured from durable GRP (Glass Reinforced Plastic), the CW4 offers excellent structural strength, corrosion resistance, and a lightweight design that simplifies transportation and installation. Its compact footprint and low-profile design ensure minimal visual impact once installed, while flexible installation options make it suitable for a variety of site conditions.

 

Third-party tested to EN 12566-3, the Clearwater BioAir CW4 combines proven treatment performance with straightforward operation and maintenance. The system is supplied with an isolator switch as standard, with an optional high-level alarm available for pumped (IPS) units. Affordable service plans are also available to help maintain optimum performance and compliance throughout the system's lifespan.


Key Features

  • Suitable for up to 12 persons
  • Advanced aeration technology for effective wastewater treatment
  • Up to 97.5% BOD₅ reduction
  • Suitable for shallow dig installations
  • Suitable for traffic loading areas (subject to structural design requirements)
  • Low visual impact installation
  • Third-party tested to EN 12566-3
  • Easy to install, operate, and maintain
  • Supplied with isolator switch as standard
  • Optional high-level alarm available for IPS units
  • Robust yet lightweight GRP construction
  • Affordable service plans available
  • 12-month manufacturer's warranty (terms apply)

 

Applications

The Clearwater BioAir CW4 is ideal for large family homes, small residential developments, holiday accommodation, offices, workshops, and other off-mains drainage installations requiring dependable sewage treatment for up to 12 users. Its compact dimensions, high treatment efficiency, and flexible installation options make it an excellent choice where space is limited but performance cannot be compromised.

 

Inlet Invert Information Details
Gravity Units - Maximum Inlet Invert 1400mm
Pumped (IPS) Units - Maximum Inlet Invert 1000mm
Inverts between 755mm and 1200mm 1 × Riser Required
Inverts between 1200mm and 1400mm 2 × Risers Required

 

 

Clearwater BioAir Data Sheet
Clearwater BioAir 4 Gravity Drawing
Clearwater BioAir 4 Pumped Drawing
Clearwater BioAir Blower & Duct Vent Drawing
Clearwater BioAir Installation & Operation Guidelines
Clearwater BioAir PIA Certificate
Clearwater BioAir 4 Neck Extension
Kingspan Extended Warranty

 

SKU: TANBIOAKLA025

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CUSTOMER REVIEWS

Rated 4.8/5 by Direct Drainage Customers

Based on over 600 verified reviews

VERIFIED REVIEW

Very helpful from the start to the finish

Items were despatched quickly and arrived the next day. Would recommend.

Title

North Hayne Farm Cottages | 26 June 2026

VERIFIED REVIEW

Cheapest price I could find for the pump

Cheapest price I could find for the pump and delivery the next day what more could you want.

Title

Sam Jukes | 5 November 2025

VERIFIED REVIEW

Great service!

I ordered a septic tank it was delivered within a week and the delivery driver left it in the exact right place and time. Would definitely use this company again, thanks so much.

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Eve Harland | December 2025

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FAQs

From choosing the right treatment plant to installation, maintenance and UK regulations, we've answered some of the most common questions to help you find the right solution for your property.

What is the difference between a septic tank and a sewage treatment plant?

A septic tank separates solids from wastewater before allowing the liquid to drain into a suitable drainage field. A sewage treatment plant goes a step further, using biological processes to treat wastewater to a higher standard before discharge. Sewage treatment plants are often the preferred choice where improved treatment performance is required.

What size sewage treatment plant do I need?

The correct size depends on the number of people your property is designed to accommodate, the expected wastewater flow and the type of property. Sewage treatment plants are commonly rated by Population Equivalent (PE). It's important to select a system with sufficient capacity to handle your property's requirements. Our team can help you choose a suitable system.

Do sewage treatment plants need electricity?

Most sewage treatment plants require electricity to operate components such as air blowers, pumps or control systems. However, power consumption varies depending on the manufacturer and model. Some systems use low-energy technology to help minimise running costs. Always check the individual product specifications before purchasing.

How often does a sewage treatment plant need emptying?

Sewage treatment plants require periodic desludging to remove accumulated solids. This is commonly carried out at least once a year, although the frequency depends on the system, usage and manufacturer's recommendations. Regular servicing and maintenance are also essential to maintain performance and help prevent costly breakdowns.

Do you supply replacement parts for sewage treatment plants?

Yes! At Direct Drainage, we supply a wide range of sewage treatment plant spare parts, including air blowers, diaphragms, filters and other essential components. Whether you're carrying out routine maintenance or replacing a faulty part, our team can help you identify a suitable replacement for your system.

Do you stock all tanks and sewage treatment systems?

We do not stock tanks and treatment systems as standard. These are supplied directly from the manufacturer. The lead times of these systems will vary. If you need an accurate delivery date, please contact us on 01388 537050.

Are your prices inclusive of VAT?

It is important to note that all prices listed on our website exclude VAT. VAT will be calculated at checkout.