Carat Indirect Rainwater Harvesting System

Delivery: 7-10 working days

£2,155.00£3,073.62 inc VAT

The Indirect-supply system is designed to support WC’s, washing machines, irrigation and outside cleaning purposes. Rainwater is collected from the roof of the property and is fed into the underground tank via the downpipes. On entry to the tank, the water passes through a filter, to prevent any debris from going into the tank. With this system, there is a pressure-sensitive pump located in the underground tank. When a valve or tap is opened, water will be pumped under pressure until the valve is closed, allowing for the system to repressurise turning the power off to the pump. From the header tank, the water is gravity fed to the WC’s etc.

It is all automatic, whenever there is a demand for water i.e. when the toilet is flushed the harvested rainwater will be gravity fed to the toilet from the header tank and then the header tank is topped up by the pump inside the underground tank. In periods without rainfall, the water level inside the underground tank will drop. When the rainwater level is too low the pump will stop pumping harvested rainwater to the header tank. This in turn will result in the rainwater level in the header tank dropping. Inside the header tank, there is a floating ball valve that controls the top-up of mains water in periods with no rain. This means that the system maximises the use of all available rainwater.

If the system is to be used for garden irrigation, an outside tap should be installed on the pipework directly off the pump. A T-junction can be used to achieve this. This will mean that the garden tap is then being supplied by direct pump pressure. (NB: when the tank is low on rainwater there will be no mains water top-up to the outside tap.) CARAT telescopic dome shaft Mini green, with PE-lid, for pedestrian loading, option with cast iron lid for vehicle loading.

SKU: N/A Category:


Indirect supply Rainwater Harvesting system package, comprising of:

  • CARAT underground tank 2700-6500 litres, without dome
  • CARAT tank dome Maxi black, with sealing set DN 100
  • CARAT telescopic dome shaft Mini green, with PE-lid, for pedestrian loading
  • CARAT Filter package 3 House, Optimax-Pro filter internal/inflow stilling system/overflow siphon/Spannfix – DN 100
  • Pump package Home Indirect

Additional information

Weight N/A
Dimensions N/A
Lid type

Pedestrian, Vehicle

Tank size (litres)

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Scope of Supply

  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. Minimax filter supplied in accordance with type of tank
  4. Submersible pump with floating water intake
  5. Float switch (connected from mains water backup unit to the underground tank)
  6. Header tank package

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
  • Submersible pump supplies harvested rainwater on demand to the header tank where it is then gravity-fed to the WCs & washing machine
  • The header tank controls the operation of the system, supply of harvested rainwater and backup mains water to the WCs
  • Dual valve system within the header tank prioritises rainwater supply over mains water, maximising the use of all available rainwater to save on mains water consumption
  • Mains water switchover point is at a lower level in the header tank and becomes operational when rainwater is not available from the underground Platin tank
  • Mains water backup supply is not reliant on power supply or pump pressure and therefore guarantees supply of water to WCs at all times

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 RS-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

Cast Iron Maxi Lid (Vehicle Loading) | Download

Extension piece options

Extension Sleeve (371003) | Download

Extension Sleeve (371015) 1000mm | Download


GRAF Platin RWH Brochure (UK Edition) | Download
GRAF Platin XL XXL | Download
GRAF Carat S RWH Brochure | Download
GRAF Carat XXL | Download
Aqua Centre Silentio Mains Water Backup Supply | Download

Data Sheets

Carat House Direct Package | Download
Carat House In-Direct Package | Download
Carat-S Eco Plus Package | Download
Carat-S Garden Comfort Package | Download
Carat-S Silentio Package | Download
Platin Eco Plus Package | Download
Platin Garden Comfort Package | Download
Platin House Direct Package | Download
Platin House In-Direct Package | Download
Platin Silentio Package | Download


Platin Garden Comfort Schematic Layout | Download
Platin Indirect Schematic Layout | Download
Platin Silentio Schematic Layout | Download
Platin Direct Schematic Layout | Download
Platin Eco-Plus Schematic Layout | Download

Carat Indirect Schematic Layout | Download
Carat Silentio Schematic Layout | Download
Carat Direct Schematic Layout | Download
Carat Eco-Plus Schematic Layout | Download
Carat Garden Schematic Layout | Download

Carat XL XXL Indirect Schematic Layout | Download
Carat XL XXL Silentio Schematic Layout | Download
Carat XL XXL Direct Schematic Layout | Download
Carat XL XXL Eco-Plus Schematic Layout | Download
Carat XL XXL Garden Comfort Schematic Layout | Download

This informative guide covers the following:

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

Read the Guide | Download

A rainwater harvesting system will cut your home's demand for drinking water by up to 50% and therefore also protect the environment. But how much time do you have to factor in for operating and maintaining such a system? GRAF rainwater harvesting systems are designed so that only very few of the components need checking. This film shows which components need maintaining and how often. The intelligent components deliver perfectly clear rainwater with minimum maintenance effort, enabling you to save drinking water and time.

Extension Pieces

(Compatible with Platin and Carat systems)

Extension Sleeve (371003) | Download

1000mm Extension Sleeve (371005) | Download

infiltration Tunnels

(Applications: Inspection & maintenance across soakaways & drainage fields)

Infiltration Tunnel | Download

One2Clean Discharging to Tunnels (Excavation Layout)| Download

Rainbloc Crates

(Applications: Surface water soakaway)

Rainbloc Specification (2020 version) | Download

New Rainbloc Instructions | Download

Distribution Shafts

(Applications: Inspection and maintenance access to soakaways and drainage fields)

Distribution Shafts Flyer | Download

Portable Water Tanks

GRAF WWT UK Brochure | Download

Wastewater Treatment Systems

GRAF One2Clean Benefit Flyer | Download

Percolation Test Guides

(Applications: Soakaways and drainage fields)

Catalogue: Portable Water Solutions | Download

Graf UK has a national service provider network of contractors who can offer various services for our rainwater harvesting & wastewater treatment systems.

See this link for UK map showing companies who can offer installation for your Graf rainwater harvesting system, just enter your postcode to highlight the companies in your area.

Setting up the pump & filter packages for the Garden Comfort systems is relatively straightforward if you follow the installation guide.

If you require assistance you can contact ‘The Rainwater Guy’, who is an accredited service provider for Graf UK for commissioning, installation of controls & maintenance of our rainwater systems.

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.
All orders are typically delivered within 5-7 working days from receipt of order, however during this time due to UK-wide disruption, some deliveries may take a little longer and we would still aim to deliver within 10 days.

• Delivery lead time is 5-7 working days on all orders, unless otherwise advised.
• 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 are generally strapped to a pallet for fork lift off-load, slings can also be used.
• Please advise if there is restricted access to site or special delivery instructions.