COVID-19 update: limited operations affecting services.
Sewage Treatment Systems
Cross section diagram of Graf Carat underground tank.
  • Cross section diagram of Graf Carat underground tank.
  • 3750 litre 7 person Graf Carat underground septic tank.

3750 Litre 7 Person GRAF Carat Septic Tank

5-7 working days
5-7 working days
£817.65 (Ex. VAT)
Not available for delivery

Delivery from £15 5-7 working days

Carbon neutral delivery from JDP vehicles

Return within 30 days for a full refund

Product Details


Capacity: 3750 litres
Max inhabitants: 7
Length: 2280mm
Width: 1755mm
Height: 2200mm
Weight: 175 kg
Warranty: 10 years

Septic tanks are a traditional solution for domestic sewage disposal, they are ideal for situations where access to mains sewer is not possible or practical.

GRAF's Carat septic tanks are divided into two parts; the sewage is collected in the first part of the tank, the removable material and floating solids are trapped there so they can break down into sludge over time. The wastewater flows freely into the second part, and then out of the tank via the outlet and into a suitable drainage field.

The Carat septic tanks are made out of 100% post-consumer plastic waste. Being made out of recycled plastic, this tank is light weight, able to be installed in tricky local conditions without a crane and you can use granular backfill instead of concrete. This highly stable design also allows you to install the tank with the water table up to half way up!

To get an idea of the size of Carat tank suitable for your project, a simple calculation to get you started is to multiply 500 litres of capacity by the number of inhabitants at the dwelling. This capacity per person is based on an approximate volume of 150 litres per inhabitant per day, and as the wastewater would take roughly 3 days to pass through the system, the 150 litres is multiplied by 3 days and rounded up to be sure!


5-7 working days
5-12 Persons
Install Type:
Product Type:
Septic Tank

Also In This Range