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GRAF Carat-XXL Rainwater Tank.
  • GRAF Carat-XXL Rainwater Tank.
  • GRAF Carat-XXL House ECO-Plus Rainwater Harvesting Package.
  • GRAF Carat House ECO-Plus Rainwater Harvesting System.

22,000 litre GRAF Carat XXL House ECO-Plus Rainwater Harvesting System

10-14 working days
10-14 working days
£8,940.16 ex. VAT

Product Details

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


Tank Type: Large Capacity
Capacity: 22,000 litres
Length: 6145mm
Width: 2500mm
Height: 3160mm
Inner Ø dome shaft: 650mm
Tank Weight: 851kg
Dome Shaft Weight: 9kg (pedestrian loading)/55kg (vehicle loading)
Warranty: 15 Years

This 22,000 litre Carat XXL House ECO-Plus Rainwater Harvesting system from GRAF is designed to be an ideal solution for use in the home and garden. Suitable for all non-potable house and garden applications, it is a fully integrated system which features the largest injection compression moulded tank of its kind.

Product Features at a Glance:

  • Economic package solution
  • Patented filter technology and in-house pump system with automatic switch-over to mains water supply.
  • Easy to assemble due to modular components
  • Float switch controlled
  • Low visual impact

Customer Notice: The processed water may be used to water the garden, flush toilets, wash clothes and as conventional cleaning water. It is Not suitable for consumption or personal hygiene.

GRAF Carat XXL Household Rainwater harvesting packages feature their patented Optimax-Pro (self-cleaning) filter that requires minimum maintenance and provides over 95% water yield. The filter housing has a transparent lid for filter visibility and can be easily removed without tools.

The ECO-Plus System features an Aqua-Center Basic control unit that checks and regulates the entire water requirement. The floating switch-controlled monitoring of the tank ensures that the unit automatically switches to mains water supply if the rainwater level drops below the predefined minimum. As soon as the tank refills with rainwater, the Aqua-Center Basic switches back to rainwater supply, ensuring that only a minimum of mains water is used during longer dry periods.

The complete package includes:

1 x Carat XXL underground tank
1 x Maxi tank dome with connection DN 150
1 x Mini telescopic dome shaft with PP cover (pedestrian loading)
 or Cast iron telescopic dome shaft with childproof cover (vehicle loading up to 3.5 ton)
1 x House XL Filter package consisting of:

    • XL Internal Optimax-Pro (self-cleaning) filter
    • Inflow stilling system for controlling the water inflow
    • Overflow siphon with rodent guard function
    • Spannfix pipe connection sleeve

1 x House ECO-Plus Pump Package:

    • Mains water feeding console including KSB Superinox 15/4
    • Floating suction set with fine filter and hose
    • Wall duct DN 100
    • Labelling set
    • V2A switch control
    • 25 m roll of HDPE suction hose (black and green)

The Carat tank series are the foundations of a long-lasting rainwater harvesting system. Manufactured by injection compression moulding, these tanks boast unbeatable stability with each component produced to the highest accuracy. The tank dome can be rotated 360° and sits on a telescopic, inclinable shaft allowing it to be easily aligned to connection pipes and installed flush with the soil level. Add to that its intelligent filter components and you have an easy to install system that ensures the best quality from your harvested rainwater. 

For more information about rainwater harvesting, and advice on how to choose a system and tank size, take a look at our supporting articles here.

Key Features of Carat ECO-Plus Tanks:

  • Self-cleaning filter - the patented Optimax-Pro self-cleaning filter delivers a water yield of over 95 % and requires minimal maintenance.
  • Very high water quality - floating extraction unit extracts the water from the cleanest zone – about 10 cm (4") below the water's surface.
  • Dome shaft - provides easy access to the filter and tank, can be fitted with covers suitable for either pedestrian or vehicle loading.
  • Versatile Tank Cover - can be telescoped and tilted in a continuously variable manner and blends seamlessly into the ground surface.
  • Suitable for Vehicle Loading - when combined with a cast iron telescopic dome shaft, meaning the Carat tank can then be installed under your driveway.


Please Note: All dimensions are approximate (the manufacturer reserve a tolerance of +/- 3%) and the useful volume of the tanks may be up to 10% lower than the tank capacity, according to the connecting option. All images shown are used for illustration purposes only and may differ from the actual product supplied.

Disclaimer: Pre-condition for warranty benefits are proper handling, assembly and installation according to the mounting guidelines. The warranty may become invalid if any of these conditions are breached.

10-14 working days
Install Type:
Below Ground
Product Type:
Large Capacity
11,000 - 20,000 litres