Commercial Rainwater Harvesting System, RainBox Gravity

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From £6,355.00

Free UK Mainland Delivery

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(Prices Exclude VAT)

System Commissioning

(Price Excludes VAT)


The “RainBox Gravity” is a complete off-the-shelf gravity fed/indirect pressure, commercial rainwater collection system.

How does it work?

Rainwater is collected from your roof area; it is then passed through a filter system which removes any large pieces of debris, leaves, etc. and then into the underground storage tank via a calmed inlet which is designed to stop the disturbance of any sediment in the bottom of the tank.

Collected rainwater is pumped from the underground storage tank via a submersible pump to a high-level header tank situated in the buildings loft/attic space.

From here the rainwater is fed by gravity to the point of use, toilets, urinals, etc.

Too much rain.

Excess rainwater will pass through a siphoned overflow fitted to the tank – to be connected to the storm drain or soakaway.

Not enough rain.

If there has been insufficient rainfall and the storage tank is running low the control system will introduce mains water into the header tank, but only the minimum required. Thus leaving maximum capacity to receive the next rainfall and ensuring there is no interruption of water supplied to the serviced appliances.

Up to 80% of commercial main water can be replaced by rainwater harvesting!


The Rainwater Storage Tank

With this system, you have the option to have a 6000, 8000, 10000, 12000, 14000-litre underground water tank. The tanks are made from robust GRP (requires full concrete surround).

They have two access turrets:

  1. 650mm dia x 500mm High.
  2. 700mm dia x 500mm High.

All tanks come with 2 x pedestrian rated covers.


The Rainwater Filter System

The storage tank is delivered to site with a pre-installed internal filter system, sediment trap, calmed inlet, non-return valve, and overflow.

The filter system is suitable for roof areas up to 2000m2.

The Submersible Pump

The pump is operated automatically by the control system. It delivers approximately 4 bar of pressure and up to 3,500 litres/hr of flow.

Built with corrosion and oxidation resistant material with a wear-resistant motor shaft.

It has dry run and thermal overheating protection and is fitted with a stainless steel debris strainer.


The Header Tank

Made from GRP with a 500, 1000, 1500, 2000-litre capacity.

Our 1500 and 2000-litre tanks have added strength with 40mm Encapsulated RHS Steel Bracing.

The tanks are fully compliant with  AB CAT 5 Airgap specification.

Inside the header tank is a float switch system which has a mechanical delay action, this means that a WC or similar demand can be flushed 4-5 times before the submersible pump in the storage tank is activated and fills the header tank.

As the pump is starting and stopping less frequently, power consumption and the life of the submersible pump will be better.

Should the underground tank become low, the header tank will continue to be depleted until the level has reached the main water top-up level.  At this point, mains water is introduced directly to the header tank. 

Optional Extras

Please get in touch if you require an ultraviolet disinfection system, etc. We can build a system to your exact requirements.

Looking for a bespoke commercial rainwater collection system?

Please contact us, we will be happy to help!





Included In The System

  • GRP Underground storage tank.
  • Internal filter system (in underground tank).
  • 2 x pedestrian rated covers (for underground tank).
  • Submersible pump (for underground tank).
  • GRP header tank.

Underground Storage Tank Dimensions

  •  6,000L – 1850mm diameter x 2700mm long
  •  8,000L – 1850mm diameter x 3350mm long
  • 10,000L – 1850mm diameter x 4230mm long
  • 12,000L – 1850mm diameter x 5070mm long
  • 14,000L – 1850mm diameter x 5800mm long
  • 16,000L – 1850mm diameter x 6600mm long

Header Tank Dimensions


  • 500L:  1180mm Wide x 1180mm Deep  x 1060mm High
  • 1000L: 1180mm Wide x 1180mm Deep x 1310mm High
  • 1500L: 1202mm Wide  x 1702m Deep x 1310mm High
  • 2000L:  2202mm Wide x 1202mm Deep x 1310mm High


This system is available with a 3-Year Warranty upon completion of a Total Water System’s system commissioning (available at an additional cost).

Commercial Rainwater Harvesting