The 16000 Litre Carat Direct Rainwater Harvesting System from GRAF supplies rainwater to your toilets, washing machine and outside taps from a Carat XXL underground tank. At 16,000 litres it suits a commercial building, school or busy farm yard.
As a guide, British Standard BS 8515 suggests a tank of around 5% of the rain your roof collects in a year, which for the 16000 litre tank works out at a roof area of roughly 535 square metres. Used for toilets and laundry, it also holds around 18 days of supply for up to 17 people.
How the Carat Direct System Works
Rainwater passes through the Optimax filter before it enters the tank, so it keeps debris out of the tank. The Divertron pump inside the tank then draws clean water through a floating intake and sends it straight to your toilets, washing machine and outside taps.
If a long dry spell lowers the level in the tank, a float sensor tells the mains back-up unit indoors to add a small amount of mains water. In other words, the unit only adds as much water as needed, so there is always room for the next rainfall and your appliances never run dry.
Key Benefits
- Cuts mains water use for toilets, laundry and outside taps
- Pump sits in the tank, so it runs quietly and stays out of sight
- Automatic mains back-up keeps water flowing during dry spells
- Only tops up the tank as needed, leaving room for rain
- Suits new builds and larger renovation projects
What’s Included
- 16,000 litre Carat XXL underground tank
- Telescopic dome shaft with 150kg pedestrian lid
- Integrated Optimax filter
- Divertron submersible pump
- Floating intake filter
- Overflow syphon
- Mains back-up unit with float sensor
- 25m roll of pressure pipe
Not Supplied
- 100mm duct pipe for the pump hose and cables
- 100mm inlet drainage pipe from the downpipes
- 100mm overflow pipe to a soakaway or surface water drain
- Electrical connection (a qualified electrician should carry this out)
Specification
- Capacity: 16,000 litres (approx. 3,520 gallons)
- Tank: GRAF Carat XXL tank with a ribbed body designed for deep burial and heavy ground loads
- Tank dimensions: 4590 x 2500 x 2550 mm (L x W x H, before dome shaft)
- Tank weight: 790 kg
- Loading: Pedestrian as standard, vehicle with the optional traffic lid
- Warranty: 15 years on the tank, 2 years on parts
- Not suitable for drinking water
- Manufacturer: GRAF UK
Optional Extras
- Traffic Telescopic Lid 3.5 Tonne, for driveways, yards and car parks
Delivery
We deliver the 16000 Litre Carat Direct Rainwater Harvesting System free to UK mainland addresses. The tank arrives on a lorry, so you will need to be able to offload it on arrival. In addition, drawings, data sheets and installation guides are available to download on this page.




















