GRAF

Flat Underdeck Stormwater Detention Tank

Rigid under-deck stormwater detention tank (3,000 and 5,000 L). Compact footprint for engineered OSD under decks and raised homes. Tank and access lid; price on request.

Brand

GRAF

Range

Stormwater

Sizes

Lid types

Size

Dimensions: L 2,450 mm · W 1,600 mm · H 1,070 mm

Lid / load class

Selected SKU

295D-3000

Price on request

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Upload plans on the quote form for civil sizing, pump station design, or treatment plant PE calculations.

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Certified qualityISO 9001 · AS/NZS standards

15-year warrantyOn selected tank ranges

Recycled plasticsSustainable manufacturing

Typical applications

Civil sites

Attenuation

Infiltration

Key features

Compact footprint for constrained residential and light commercial sites

AU catalogue sizes: 3,000 L and 5,000 L

Scope of supply: tank plus Garantia access lid (part 202803)

Lower side connections support manifolded banks for larger detention volumes

Serviceable 600 mm access for inspection and maintenance

Technical sizing

Size matrix & SKUs

2 technical rows - select above or quote directly

Size	Length	Width	Height	Weight	Lid / variant	Load class	Order no.	Quote
3,000 L	2,450 mm	1,600 mm	1,070 mm	130 kg	Access lid	Access lid	295115
5,000 L	2,450 mm	2,100 mm	1,340 mm	200 kg	Access lid	Access lid	295126

Nominal tank dimensions; rotational moulding tolerances of about ±3% may apply.
Approx. overall height with flat lid: 1,120 mm (3,000 L) and 1,390 mm (5,000 L).
Access lid part 202803 (approx. 600 mm), short-duration walking load 150 kg.
Requires a flat, continuously supporting base; permanent shade for freestanding outdoor warranty.
Tank must not support deck structures, vehicles or other imposed loads.

Full specification

Product details

Key construction, installation and performance notes for Flat Underdeck Stormwater Detention Tank.

Overview

The Flat Underdeck Stormwater Detention Tank (4rain by GRAF) is the same rigid flat tank platform configured for engineered on-site stormwater detention under decks, raised homes and permanently protected spaces. Pair the tank and access lid with project-specific controlled outlets, overflow and inspection details.

Specification focus

Compact footprint for constrained residential and light commercial sites

AU catalogue sizes: 3,000 L and 5,000 L

Scope of supply: tank plus Garantia access lid (part 202803)

Lower side connections support manifolded banks for larger detention volumes

Serviceable 600 mm access for inspection and maintenance

Detail 01

Key features

Compact footprint for constrained residential and light commercial sites
AU catalogue sizes: 3,000 L and 5,000 L
Scope of supply: tank plus Garantia access lid (part 202803)
Lower side connections support manifolded banks for larger detention volumes
Serviceable 600 mm access for inspection and maintenance

Detail 02

Application

Engineered stormwater detention designed and installed to project and authority requirements. Not a general-purpose above-ground tank, and not for vehicle or trafficable loading.

Technical documents