Welcome, Guest ( Login )

LARR/IAPMO Certified Solutions

LARR/IAPMO Certified

RainHarvest Systems offers high quality GRAF underground rainwater harvesting tanks that have been tested and are listed by IAPMO (International Association of Plumbing & Mechanical Officials) R&T to Standard Z1002 as determined by Los Angeles Research Report (LARR) 5755.

Carat S Underground Tanks

The lineup consists of four modular tank units ranging from 700 gallons to 1700 gallons which are expandable up to thousands of gallons. The precision, modular, and ultra-high strength design of the Carat S makes it the choice of professionals worldwide. The GRAF Carat tank is guaranteed not to collapse when empty when installed per the manufacturer’s specifications.


  • 15 year manufacturer’s warranty
  • Suitable for vehicle loading (when combined with the cast iron lid option)
  • Variable installation depth with double-sealed telescopic riser
  • Convenient 31-1/2” manway opening
  • Frost-proof installation underground
  • Attractive locking green lid
  • Internal pre-filtration option
  • Easy to transport and install
  • Ultra-high strength materials and design
  • Groundwater stable to the middle of the tank
(US Gallons)
700 1000
(Expansion Tank)
Part No.
372001 372002 372026 372004 372014
265 lb. 331 lb. 408 lb. 485 lb. 485 lb.
82" 90" 90" 94" 94"
62" 69" 78" 86" 86"
55" 62.5" 71.5" 82.5" 82.5"
79" 86.5" 95.5" 106.5" NA
66" 73.5" 82.5" 93.5" NA

*Htot = total height    **with Mini Tank Dome.       Deeper burial depths can be achieved using optional extension rings

Carat S underground tanks are approved under Section, 94.301.0, 94.309.0, and 1602.9.5 of the Los Angeles Plumbing Code, 2020 Edition and are subject to the following conditions:

  1. These products are intended to be used for rainwater harvesting purposes.
  2. These products shall be installed underground inside or outside the building footprint. Above ground installations are not allowed.
  3. These products shall be assembled, installed, and maintained in accordance with the manufacturer’s printed installation instructions and the Los Angeles Plumbing Code, 2020 Edition.
  4. These products shall be installed to meet all rainwater harvesting system requirements as mandated by Chapter 16 of the LAPC, 2020 Edition.
  5. The tank shall be marked with the manufacturer’s name, product model number, working liquid volume, date of manufacture, maximum design loads and maximum burial depth where visible for inspection purposes.


Value Added Products