How does the Carat In-Direct Rainwater Harvesting System work?
The indirect supply system is designed to support WCs, washing machines, irrigation, and outside cleaning purposes. Rainwater is collected from the roof of the property and 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 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 imply that direct pump pressure is now supplying the garden tap. (NB: when the tank is low on rainwater, there will be no mains water top-up to the outside tap.)
Why choose the Carat In-Direct Rainwater Harvesting Package?
- Innovative Gravel Backfill: Our system uses gravel backfill, significantly reducing installation costs by £60 per cubic metre compared to concrete.
- Adaptable Installation with Vehicle Loading Lid: Space constraints? The vehicle loading lid allows for installation under driveways, maximising space and utility.
- Environmentally Responsible Design: The underground tank is made from 100% recycled plastic, showcasing our commitment to sustainability.
- European Market Leader Quality: Trust in a product renowned for its reliability and effectiveness in rainwater harvesting.
- Efficient Water Management: Equipped with an automatic submersible pump featuring automatic restart and dry-run protection, it ensures smooth and low-maintenance operation.
- Consistent Water Supply: The system includes an integrated mains water back-up, which automatically tops up the header tank with mains water when rainwater levels are low, guaranteeing a continual water supply.
Images are for illustrative purposes only, there is a possibility that certain products may have been upgraded or replaced with equivalent alternatives.
It's essential to inform your local water authority before starting any work. According to the Water Supply (Water Fittings) Regulations, installing systems like rainwater harvesting is considered a "material change of use" of your premises. This means you must notify your water undertaker in advance and obtain their consent before beginning the installation.
To notify your local water authority, you'll need to provide details such as your name and address, a description of the proposed work, and specifics about the location and intended use of the premises. Many water undertakers have their own notification forms available on their websites. It's important to use these forms, especially when submitting electronically.
By following these steps, you help ensure that your rainwater harvesting system is installed safely and in compliance with regulations, protecting both your water supply and the broader public system. For any further guidance, please click here.
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

Vehicle Loading Lid (371052) | Download
Extension piece options

Extension Sleeve (371003) | Download

Extension Sleeve (371015) 1000mm | Download
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
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 forklift off-load, slings can also be used.
• Please advise if there is restricted access to the site or special delivery instructions.