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Harlequin CAP15 (up to 15 person) Sewage Treatment Plant | CAP15

£3,891.00
£4,669.20 (inc VAT)
£3,891.00 (exc VAT)

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Product Description

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

 

The Harlequin CAP15, compact sewage treatment plant, is specifically designed to treat domestic sewage in a simple and compact system making sure it is safe to be discharged into a watercourse such as a river or stream. It is suitable for domestic installations of up to 15 people. With a life expectancy of over 20 years, you can enjoy absolute peace of mind.

Manufactured from durable Medium Density Polyethylene (MDPE) material, the CAP15 is one of the most stable and easy to install sewage treatment plants. It’s unique bio media system delivers a pollutant removal level of 96.2% whilst also combatting common problems associated with small packaged domestic plants. Contemporary design engineering and analysis software and state-of-the-art manufacturing facilities combine to create this unique product which dominates the domestic sewage treatment plant market. Market-leading performance, easy installation, super quiet operation, low maintenance costs, reliable bio media system and durability are all qualities that make the product best suited for a wide range of off-mains sewage treatment requirements.

CAP15 comes in both gravity and pumped outlet versions. Its equipped with an external blower for optimal performance. The blower is conveniently located in a weatherproof aboveground external housing. This compact system comes with a 2-year warranty (only when product is registered on our website) and is certified for use in the UK in compliance with EN12566-3.

 

Features
  • Tank body moulded in one piece from durable Medium Density Polyethylene Material (MDPE)
  • 110mm inlet and outlet connections
  • 110mm services duct
  • Integrated lifting eyes for ease of handling and installation
  • Fully secured 600x450mm pedestrian duty flush fitting manhole cover to comply with statutory regulations
  • Above ground air blower housing delivers more reliable and efficient operation; allows easy access for maintenance
  • Moving Bed Biofilm Reactor (MBBR) system ensures there is no fixed media, eliminating blockages
  • Easy access to the bubble diffuser within the tank
  • Compact size and lightweight ensures lower installation costs
  • Super quiet when installed correctly
  • 12-month service period reduces operating costs
  • Mechanically reliable with no moving parts or electrics within the tank
  • Certified for use in UK in compliance with EN12566-3

 

Population Served 13-15
Desludging Interval 12 months (depending on usage)
Inlet Invert 600mm
Outlet Invert 750mm
Blower Rating 105W
Length 3615mm
Width 1620mm
Height 2140mm
Weight 600kg
Manhole Cover Size 600mm x 450mm


Super Quiet – With a high performance Linear diaphragm blower housed in a weatherproof aboveground external housing, the operation of the plant is super quiet.


Low Maintenance Costs – There are no mechanical moving parts or electrical components within the plant allowing for extremely safe and easy maintenance. At full occupancy the systems need to be emptied only once every 12 months which effectively means you spend less on maintenance of the plant.
Odourless – The plant is hermetically sealed eliminating any odour emanating from within the tank.

Market leading performance – Producing an excellent 96.2% pollutant removal level, the final effluent can be directly discharged into a stream or soakaway.
Reliable Bio Media System - The plant operates with a unique bio media system meaning there is no fixed media eliminating blockages that are commonly found in smaller treatment plants.

Durable & Stable Product - Made from MDPE, this is one of the most durable and stable sewage treatment plants you will find in the market. The wide base gives it the added stability. Once installed, you can enjoy complete peace of mind.

 

Harlequin CAP15 Installation Guide 
Harlequin CAP 15 Product Drawing
Harlequin CAP 15 Specification Sheet

SKU: TANCAPTHAR004

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Need help choosing the right tank? Call our team on 01388 537050.

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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.