Carat Silentio Rainwater Harvesting System
Carat AA Silentio Rainwater Harvesting System
Carat Silentio Rainwater Harvesting System
overflow syphon odour prevention
floating intake vavle
Minimax_Optimax Filter

Carat AA Silentio Rainwater Harvesting System 2700-6500 Litres

£3,672.10£4,285.36 inc VAT

Experience the pinnacle of sustainable living with the Carat AA Silentio Rainwater Harvesting System. Brought to you by the European market leader in rainwater collection, GRAF. This innovative system efficiently captures rainwater for non-potable uses around the home, including toilet flushing, washing machines, and garden irrigation. Featuring an underground tank made from 100% recycled plastic that can be surrounded with a gravel backfill, no concrete is required. The award-winning filter technology inside the tank ensures leaves and debris are removed before entering the tank, and the floating water intake sits just below the surface of the water, ensuring only the cleanest water is extracted. Unique to the UK, we offer the only external pump unit that incorporates a Family A Type A air gap, ensuring safety and compliance. Plus, we also offer free UK mainland delivery.


FREE Delivery by Monday, 27 May, 2024.


Protecting you


GRAF, a pioneer in European rainwater solutions, has created the Carat AA Silentio Rainwater Harvesting System, which offers a cutting-edge and environmentally friendly method of managing your household’s water needs. This system is expertly designed for various applications that don’t require potable water, including flushing toilets, washing machines, garden irrigation, and outdoor cleaning.

How It Operates:

  • Efficient Rainwater Capture: Rainwater is collected from your roof and channelled into an underground tank via downpipes, ensuring maximum collection.
  • Pristine Water Quality: As water enters the tank, it passes over an award-winning filter, preventing debris from entering the storage area.
  • Smart Water Distribution: The system includes an internal pump/control unit, which draws water from the tank as needed, ensuring efficient water usage.
  • Seamless Transition to Mains Water: When rainwater levels are low, the system automatically switches to mains water, stored in a cistern under the wall-mounted pump.
  • Optimal Rainwater Utilisation: By avoiding the use of mains water to top up the tank, the system maximises rainwater collection.
  • Digital Monitoring: A digital level indicator in the tank allows precise control and monitoring of water levels.

Key Features:

  • Sustainable Construction: The underground tank is made from 100% recycled plastic, showcasing a commitment to environmental responsibility.
  • Unique Pump System: Plus, enjoy peace of mind regarding water regulations with our external pump unit that incorporates a Family A Type A air gap.
  • Easy Installation: The tank can be backfilled with gravel, not concrete, simplifying the installation process.
  • Complimentary Delivery: Free UK mainland delivery is included, adding value to your purchase.

The system also includes a Carat telescopic dome shaft Mini Green with a PE lid, suitable for pedestrian areas, and an option for a vehicle loading lid for areas with vehicle traffic. Choose the Carat AA Silentio Rainwater Harvesting System for a state-of-the-art, eco-efficient water management solution in your home. Images are for illustrative purposes only, there is a possibility that certain products may have been upgraded or replaced with equivalent alternatives.

What’s included

  1. Underground tank (choice of tanks available, sizes vary according to property type)
  2. Telescopic lid (choice of telescopic lid available, depending on tank location)
  3. Filter (Optimax filter supplied in accordance with type of tank)
  4. Floating water intake
  5. AA Silentio unit
  6. Float sensor (connected from Silentio unit to the underground tank)
  7. Reversible flow filter

Supplied by Others

  1. 100mm diameter duct pipe to contain; float sensor cable, power cable for pump, also bringing mains water to underground tank as and when required
  2. 100mm diameter drainage pipe connected from downpipes to the inlet at the top of the tank (all downpipes brought into one pipe for connection to the filter)
  3. 100mm diameter pipe for overflow from the tank to mains drainage network or soakaway

System Benefits

  • Simple & quick to install
  • The Silentio is a wall-mounted pump that supplies harvested rainwater on-demand to WCs, washing machines & any external taps
  • The black cistern at the top of the AA Silentio is filled with mains water. The water is drawn from this cistern when the rainwater in the Carat tank is low. This gives the system mains water backup.
  • Innovative float sensor detection on the AA Silentio unit ensures that the household is constantly supplying water to the property but only the amount necessary.
  • Maintenance and servicing of the AA Silentio are straightforward as the pump is located above ground where it can be easily accessed.
  • A reversible flow filter is included in the AA Silentio package, this filter gives the system another level of filtration.
  • Water level reader inside the underground tank relays an accurate reading of the amount of rainwater left in the tank.
  • AA Silentio package comes with a jet wash feature for the filter inside the tank which periodically removes any debris on the filter.

Product Dimensions, Levels & Weights

Carat Tank Dimensions & Weights (2700L – 6500L)

Carat S 2700L Mini | Download
Carat S 2700L Maxi | Download
Carat S 3750L Mini | Download
Carat S 3570L Maxi | Download
Carat S 4800L Mini | Download
Carat S 4800L Maxi | Download
Carat S 6500L Mini | Download
Carat S 6500L Maxi | Download

CARAT Series Installation and maintenance instructions | Download
CARAT Tank Levels Mini Dome | Download
CARAT Tank Levels Maxi Dome | Download

Mini & Maxi Lid Dimensions

PE Mini Lid (Pedestrian Loading 371010) | Download

PE Maxi Lid (Pedestrian Loading 371011) | Download

Vehicle Loading Maxi Lid (Vehicle Loading 371052) | Download

Extension piece options

Extension Sleeve (371003) | Download

Extension Sleeve (371015) 1000mm | Download



GRAF Carat S RWH Brochure | Download

Data Sheets

Carat-S AA Silentio Package | Download


Carat AA Silentio Schematic Layout | Download

Installation & Commissioning

This informative guide covers the following:

  • Loading information
  • Tank coverage heights
  • Excavation dimensions
  • Technical & general data
  • Installation & Assembly

Read the Guide | Download
Read the Guide (Tank Only) | Download

Service Provider Support

GRAF UK has a national service provider network of contractors who can offer various services including the installation of our tank systems.

Coming Soon: New UK map with the service provider/installer contact details.

Delivery Information

Please note the following regarding Graf UK deliveries:

We’re still delivering to our customers safely via our own delivery vehicles & drivers in the main, using external hauliers when required.

This gives us much greater control & flexibility over our deliveries.
Delivery times stated are from receipt of order/payment & may vary subject to tank size & stock availability.

  • Delivery lead time is 5-15 working days for tanks up to 10,000L in size, subject to stock availability.
  • Delivery lead time is 15-25 working days for tanks above 10,000L in size, subject to stock availability.
    Price includes delivery to mainland UK.
    • Please check for deliveries into Cornwall, Mid & Northern Scotland & Isles as additional delivery charges may be applicable.
    • We cannot currently provide a tracking number for all orders but can accept customer enquiries by phone.
    • Off-loading by the customer unless agreed otherwise
  • Tanks up to 1200L are generally delivered by carrier strapped to a pallet for forklift off-loading.
    Tanks up to 7500L are generally strapped to a pallet for forklift off-loading.
  • Tanks 8500L & above are generally supplied with slings for off-loading.
    Please advise if there is restricted access to the site or special delivery instructions.



Weight N/A
Dimensions N/A
Lid type

Pedestrian, Vehicle

Tank size (litres)

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