1250 Gallon Underground Rainwater Tank with Riser and Locking Lid
The Graf Carat S 1250 Gallon Underground Cistern is engineered for serious rainwater harvesting performance in residential and light commercial settings. It’s strong enough to stay stable even when empty, groundwater-stable, frost-proof, and made for quick assembly without tools. Whether you’re collecting rainwater for irrigation, toilet flushing, or backup supply, this underground tank offers long-term durability, flexibility, and easy installation.
With a secure locking lid, modular design, and optional filtration or vehicle-loading upgrades, this system is ideal for anyone looking to store water safely underground with peace of mind.
Warranty: 15-Year Manufacturer Guarantee when installed according to specifications.
The Tank Guaranteed Not to Collapse When Empty* * When installed in compliance with manufacturer's installation instructions.
Features and Benefits of the Graf Carat S 1250 Gallon Tank
✓ Fully Usable 1250 Gallons – Optimized for real-world use, this tank gives you the full storage capacity without hidden losses or overestimation.
✓ No-Collapse Construction – Guaranteed to remain stable when empty if installed per the manual, unlike most underground cisterns on the market.
✓ Quick Assembly, No Screws – Installs in minutes with a patented connection system that requires no tools and allows for easy disassembly.
✓ Ground-Level Finish with Safety Lid – Includes a 14" telescopic riser and childproof locking lid that adjusts to surface grade and tilts for perfect alignment.
✓ Flexible Burial Depths – Bury between 30"–42" standard or go deeper (up to 70.9") with optional risers — even in groundwater.
✓ Safe, Clean Rainwater Collection – Multi-layer sealing system keeps dirt and groundwater out, protecting water quality for non-potable use.
✓ Expandable System – Easily add additional tanks or filters to scale up your system as your needs grow.
✓ Rotating Tank Dome – Dome rotates and tilts up to 5°, making pipe alignment easier and reducing installation time.
✓ Built to Last – Made from recyclable Duralene with TÜV-certified construction and backed by a 15-year warranty.
Specifications for the Graf Carat S 1250 Gallon Underground Tank
| Capacity |
1250 Gallons (Fully Usable) |
| Construction |
High-Quality Duralene Plastic |
| Manway Opening |
31.5 inches |
| Riser Included |
14-inch Telescopic Riser |
| Lid Type |
Childproof PE Locking Lid |
| Groundwater Stability |
Up to the top of the tank (standard), middle with risers |
| Vehicle Load Rated |
Optional, up to 2.2 tons axle load |
| Installation Type |
In-Ground, Frost-Proof |
| Adjustability |
Dome rotates and tilts up to 5° |
| Warranty |
15 Years (Manufacturer) |
The Tank Guaranteed Not to Collapse When Empty*
- 1250 fully-usable gallons
- Attractive Riser and Locking Lid Included
- Car-bearing Option Available
* When installed in compliance with manufacturer's installation instructions
Easy and Safe Assembly
- The patented quick connection (illustrated in green), allows the Carat tank to be assembled without screws in only few minutes. Disassembly is possible at any time.
- The first-class EPDM material used in the profile seals (illustrated in yellow), has been laboratory tested to last more than 25 years.
- The centering bolt (illustrated in orange) assures the accurate and easy assembly of the two half shells preventing any leaks
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Flush with ground level (2 seals) |
| The Carat S underground tank has numerous seals to effectively stop dirt getting into the tank. This means that seepage water cannot get into the tank and, thus, dirt particles cannot contaminate the rainwater. The seals are in the intersection between the tank and the tank dome and between the tank dome and the telescopic dome shaft. All supply pipes connected to the tank dome are also sealed with five lip seals as standard. |
Application
- The global innovation – the new tank generation of the Carat rainwater underground tanks have been specially developed for rainwater harvesting
- Frost-proof installation underground
- Groundwater stable up to the middle of the tank due to extremely rigid construction
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The tank that turns its head for you
The GRAF Carat S underground tank has a rotating tank dome. The tank dome can be aligned with the connections independently of the tank – this makes installation much easier! All installation pipes are connected using the five standard lip seals. The Carat S telescopic dome shaft connects the system to the ground surface. The height of the tank can be smoothly adjusted to suit the local conditions and it can be tilted by 5°. The whole system is flush with ground level.
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Logistical Advantages of the Carat
The Carat tank consists of two half shells which can be stacked on top of each other, allowing multiple tanks to be stacked on a single pallet for shipping. For example, it is possible to stack five 1,700 gallon Carat tanks on a single pallet. This allows a standard 40 ft. shipping container to house a total tank volume of up to 34,000 gallons! The tanks' unique stacking feature directly reduces transport costs and environmental impact from vehicle emissions.
| Vehicle Loading Option |
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Includes heavy duty telescopic dome shaft and cast iron lid for vehicle loading up to a maximum axle loading of 2.2 tons.
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Manuals and Warranty
Warranty: 15-Year Manufacturer Guarantee when installed according to specifications.
Return Policy
If you are not satisfied with your purchase, please send an email to support@thefountaindirect.com or call us to request a Return Material Authorization (subject to manufacturer approval) prior to returning any merchandise. Requests for returns on standard, non-special-order items may be made within 30 days of the item's ship date.
In order to provide our customers the highest quality products at the lowest possible prices, we only accept returned merchandise in "factory new” condition. We must be able to resell the product as new in the condition it is returned to us.
