GRAF Carat 3750L poly septic tank
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GRAF Carat 3750L Septic Tank

The everyday tank. Sized for a busier household or a SmartShift cluster up to about 6 inhabitants. Same dual-chamber baffle design and telescopic lid as the 2700 L, with a deeper body for extended retention and treatment of greywater and blackwater.

From $3,770
3,750 L
Total capacity
6
Inhabitants
2280 mm
Length
2200 mm
Height
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Full specifications

Full specs, dimensions and compliance.

Capacity & sizing

Total capacity
3,750 L
Base capacity
2,000 L (4 inhabitants)
Per-extra-person
+500 L
Treatment cycle
~3 days mechanical
Suits household
Up to 6 people

Dimensions & weight

Length
2,280 mm
Height
2,200 mm
Width
1,755 mm
Lid type
Telescopic, tiltable
Install method
Drop-in, no crane required

Build & compliance

Material
Polyethylene (100% recycled)
Standard
AS/NZS 1546.1
Chambers
Dual-chambered with internal baffle
Lid
Telescopic, tiltable
Concrete anchoring
Not required
Driveway-rated
Yes — with optional trafficable lid
Origin
Germany (Otto Graf GmbH)
Warranty
10 years (manufacturer)
What's supplied

Complete tank package.

Supplied as a full GRAF Carat kit. Optional trafficable lid available for driveway placement. Free delivery within Perth metro area.

  • GRAF Carat poly septic tank body
  • Internal baffle for dual-chamber separation
  • Telescopic lid (tiltable for fall adjustment)
  • Standard non-trafficable cover
  • Inlet & outlet pipe seals
  • Manufacturer installation guide
  • Free delivery within Perth metro (Alkimos–Mandurah)
Standards & install

Australian-compliant install.

Excavation, ground preparation, plumbing connection and council approval are the installer's responsibility. Standards your installer works to:

  • AS/NZS 1546.1 — On-site domestic wastewater treatment units (Septic tanks)
  • AS/NZS 1547 — On-site domestic wastewater management
  • Local council approval typically required for installation
  • Licensed plumber for connection to building plumbing (AS/NZS 3500)
We deliver the tank to your site (free within Perth metro). Excavation, plumbing connection and council sign-off are arranged by your licensed plumber — ask us for recommended installers in your region.
Get started today

Bigger household
or shared site?

Tell us the household size, soil type and council region — we'll confirm the 3750L is the right pick and send a quote with delivery.

No obligation
Prompt response
Free Perth metro delivery
10 yr manufacturer warranty
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