Skip to main content
3,800 litre 12 Person Klargester Sigma Shallow Dig Septic Tank.
  • 3,800 litre 12 Person Klargester Sigma Shallow Dig Septic Tank.

3,800 litre 12 Person Klargester Sigma Shallow Dig Septic Tank

Klargester KLSTH038
6-8 working days
£1,526.56 ex. VAT
Free Delivery (Restrictions Apply)

Product Details

This item is supplied to order and additional refund & returns terms apply.


Capacity: 3,800 litres (836 Gallons)
Max inhabitants: 12 people
Overall diameter:1225 mm
Overall length: 3895 mm
Weight when empty: 185kg
Manhole opening: 600 x 600mm
Standard inlet invert: 500 mm
Standard outlet invert: 530 mm
Depth: 1617/1577*

Septic Tanks are a traditional answer for domestic sewage disposal when it isn’t possible to connect to a mains sewer system. Klargester’s Sigma Septic Tanks are designed to reduce installation time and cost and be suitable for properties with dig height restrictions. Made from Glass Reinforced Plastic (GRP), this range of tanks are strong but light, watertight and also chemically resistant. They are performance tested in accordance with EN-12566 (Part 1) to make sure that they meet installation requirements and that the standards of discharge are as they should be.

Key Features of Klargester Sigma Shallow Dig Septic Tanks:

  • Manufactured from composite GRP – strong & durable for ultimate reliability
  • Light, watertight and chemically resistant
  • Robust, weatherproof for guaranteed durability
  • Reduced excavation costs
  • Less soil disposal and less backfill material – kinder to the environment
  • Fully compliant, tested and approved to EN 12566 (Part 1)
  • CE marked to comply with Construction Products Regulations (July 2013)
  • Come complete with an A15/pedestrian cover and frame.

This 3,800 litre Klargester Sigma Septic Tank is formed from a single chamber into which the sewage from a domestic property or small business premise is collected and retained. Over time, the solids are digested anaerobically, breaking them down into sludge, and the surplus effluent liquid leaves the tank via the outlet. To disperse the resultant liquid you will require a suitable drainage field system. Take a look at our article on How to size a septic drainage field for more information on this.

Typical applications for Klargester Sigma Septic Tanks include:

  • Single/Multiple Homes
  • Caravan & Camping Sites
  • Golf Course Toilet/Washroom Facilities
  • Churches
  • Mobile Homes/Static Caravans
  • Farms
  • Temporary Work Offices
  • Offices/Light Industrial Premises
  • Temporary Dwellings & Welfare Facilities

When planning your installation, make sure that these systems are installed at least 7 metres away from any sort of dwelling and that they are at least 10 metres away from any watercourse.

Why Shallow Dig?

The shallow dig design of this septic tank can save you money on site! You won’t need to excavate as much as you would with a traditional spherical tank, meaning it usually quicker to install and reduces the chance of ground water issues. It’s a win-win! They're also known as horizontal septic tanks.

Important Manufacturers Notice:

Basic septic tanks only retain solids and discharge effluent of low quality. The installation will not contaminate any ditch, stream or other watercourse. However, many authorities in the UK prohibit their use. In all instances a sewage treatment system should be considered as a first option. Septic tanks may be installed, subject to consent, in applications where:

  • Soil is of suitable porosity.
  • Installation complies with Building Regulations (Approved Document H).
  • The installation will not contaminate any ditch, stream or other watercourse


Please note: max inhabitants is indicative usage of 150 litres/per person/per day. All images are used for illustration purposes only and may differ from the actual product supplied.

*110mm Diameter Pipework/160mm Diameter Pipework

6-8 working days
5-12 Persons
Install Type:
Shallow Dig
Product Type:
Septic Tank