Read more about the importance of filtration in a rainwater harvesting system

Read more about the water quaity from of our rainwater harvesting systems.

Not sure which tank you need?
Use our calculator to find out.

Learn about looking after a rainwater harvesting system.

raintech gravity
Indirect (header tank) system
Use Me For
WC Flushing
washing machine
watering can
car washing
diagram commercial rainwater harvesting
  • Gravity feed system
  • Easy maintenance (filter is accessible from ground level)
  • No need to empty main storage tank to clean filter
  • BS8515 compliant (tank is fitted with an anti backflow and rodent guard)
  • Headertank to protect against power failure
  • Oxygen adding filtration due to Wisy Vortex:
    • Advanced Wisy Vortex filtration removing debris without allowing it to degrade on a horizontal filter mesh
    • Pre-tank Filtration to 0.28mm
    • Floating suction set with 0.3mm mesh filter
  • Flexible system design
  • Variable speed pump options
  • BMS alarm output options
  • Full system monitoring options available
  • System commissioning included
RainTech® Commercial Gravity Indirect

The RainTech® commercial gravity system is ideal for low pressure use to feed WCs and other outlets in many buildings, providing there is space available at a sufficiently high level. This provides a simple but robust solution: in the event of lack of rainfall, or even pump failure, the header tank will continue to run on mains water. The header tank is sized according to requirements, and the system is fitted as standard with a BMS compatible control panel, or optionally with an advanced commercial gravity system controller.

Standard Equipment

Rainwater header tank

The rainwater header tank has both mains water and rainwater inlets. Built in accordance with UK water regulations, our RainTech® header tanks have AA or AB air gap for mains water entry. The mains water supply can sized to accommodate various flow rates to cater for even the largest application.

Rainwater header tank
water pump submerible

Stainless Steel submersible pump

The stainless steel submersible pump delivers water from the main rainwater storage tank to the header tank. The Multigo range can be single or 3 phase and will be sized according to the distance between the rainwater tank and the header tank – the system will be designed according to your specific site. All the fittings and 32mm green and black pipe are supplied in accordance with BS8515

Advanced filtration

The 0.28mm (280 micron) fine filtration provided by the WISY VORTEX filter protects the tank from any debris and offers additional benefits such as increased oxygen for clearer water, and easy safe cleaning. This prevents any debris getting into the tank and breaking down in the water. The Wisy Vortex filter is unique in its operation and with its patented design, is unrivalled in terms of quality.

WISY Vortex WFF100 Filter rainwater filter
RainTech® GRP Underground Tanks

UK made tanks manufactured to BS 4994 from high grade GRP; 100% glass fibre / resin mix with no fillers. These tanks are manufactured to our own specification to comply fully with BS 8515. This includes our unique Multisiphon overflow trap with built-in backflow protection.

Note: It is a requirement of the British Standard for rainwater harvesting that all rainwater tanks are protected against backflow. Most tanks are supplied without this feature, so it has to be added by the installer downstream of the tank itself. Our RainTech® tanks are always fitted with backflow protection.

Tank (Litres)Length (mm)Diameter (mm)
500030801670
600027001840
750033501840
1000044501840
1200052501840
1400060501840
1600069001840
1800043502620
2200051002620
2600058502620
3400073802620
3800081502620
4000082002700
4500090502700
5000099502700
55000109002700
60000118302700
65000127702700
70000137102700
75000147002700
80000158002700
90000175602700

The RainTech commercial gravity system is capable of a number of additional features as below:

  • UV Sterilisation (including pre-UV particulate filters)
  • Full system monitoring via touch screen display or web interface.
  • Monitoring capabilities:
    • Rainwater tank water level
    • Rainwater usage (via pulsed water metre)
    • Mains Water consumption (via pulsed water metre)
    • UV Lap status
  • Multi Alarm output to BMS or control panel
    • Pump Failure alarm
    • Excess run time for pump or mains
    • Rainwater tank dry
    • UV lamp strength alarm
  • Web Interface
  • Soft Start pump
  • Low profile rainwater filter
  • Jet spray cleaning facility for rainwater filter
  • Automation of jet cleaning
Energy saving rainwater system
Energy Saving
BS8518 Compliant Rainwater systems
BS8518 Compliant
Easy to clean filter
Easy to Clean
0.2mm Fine Mesh Filter
0.28mm Mesh Filter

Read more about the importance of filtration in a rainwater harvesting system

Read more about the water quaity from of our rainwater harvesting systems.

Not sure which tank you need?
Use our calculator to find out.

Learn about looking after a rainwater harvesting system.