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Rain Activ Dual Gravity Fed System

Rain Activ Dual Gravity Fed System

Rain Activ storm attenuation system manufactured by RainWater Harvesting Ltd controls the rate of storm water discharge from site as well as being able to utilise the rainwater for non potable use within your home and garden. Full specification service and planning authority recognised Micro Drainage™ calculations are supplied with each system.

We provide calculations as this is a bespoke system.
Please call us on 01733 405 104

More details...

Unavailable product

£ 2,627.00

Tax excluded

Rain Activ House DiagramThe Rain Activ Dual Gravity Fed System gives you the ability to enjoy the benefits of rainwater harvesting in your home and garden whilst at the same time acting as part of your on site SuDS solution. The system includes the WRAS approved Rain Director mains water backup unit with smart header tank.

The underground tanks come in a range of sizes from 1,500 litres to 15,000 litres.

The bottom portion of the tank is used to store the required rainwater for use within the home and garden. The top portion of the tank is the attenuation capacity as specified by the Micro Drainage™ calculations that are generated for each situation.

How do we work out the split?

The first part is to calculate the attenuated volume required based on the information listed below along with the required discharge rate of the site. Once we have done this we then use a Tank Size Calculator to establish the amount of rainwater you would need to store to supply water to your home. This is then added onto the attenuated volume as specified by the Micro Drainage™ calculations.

Rain Activ

As well as simply reducing costs, Rain Activ far outperforms its competitors in numerous key areas:

  • Industry leading, ultra low storm water discharge rates.
  • Professional calibration.
  • Arrives to site fully assembled and ready to install.
  • No moving or consumable parts, fully self-cleaning.
  • Discharge rate calibrated between 0.05 - 1.95 L/S
  • Add rainwater harvesting for a very small extra cost

How Does Rain Activ Work?

Rain Activ SuDS Inlet Rain Activ utilises a simple to install, pre-assembled, shallow dig rainwater storage tank, along with a self cleaning filter and a controlled discharge valve. Rainwater from the roof is heavily filtered as it enters the tank, removing any particles larger than 1mm. Once the rainwater reaches a set point within the tank it is discharged at a controlled rate. Due to the quality of filtration involved, a very small orifice can be used without the risk of blockage. For this reason, the Rain Activ can provide industry-leading rates of discharge as low as 0.05l/s.

Every system sold is bespoke, and calibrated to each site’s requirements. Our engineers use Micro Drainage™ hydraulic modelling software to ensure the system discharges at the desired peak rate during a storm event. As the system already contains various key components, such as the tank and high quality filtration, the addition of a submersible pump and management system turns the system into a full domestic rainwater harvesting system.

Ultra Low Discharge rates

Rain Activ Filter Rain Activ delivers new industry low levels of storm water discharge. The systems can be calibrated to provide a calculated discharge value as low as 0.05 l/s up to 2 l/s dependant on site requirement. With discharge levels this low, the Rain Activ provides a solution for sites that have previously found meeting storm attenuation criteria difficult or impossible. These include:

  • Smaller developments (1-25 homes) where the rate of storm water is not great enough for effective use of vortex flow control.
  • Greenfield sites.
  • Sites with very low discharge rates stipulated by planning.
  • Contaminated sites.
    *Fully enclosed system with a max excavation depth of 1.5m

The Rain Activ produces a much flatter discharge curve than other storm attenuation systems. This means the system can help reduce stress on the drainage network over a greater range of storm, rather than being calibrated to one specific event.

Calibrating The Rain Activ

Micro Drainage Our design team calibrates every Rain Activ bespoke to site requirement; both the peak discharge rate and volume of attenuation. Our extensive hydraulic modelling, lab testing and field testing provides academically supported data in order to calibrate the system correctly.

  • Required run off rate.
  • Roof size.
  • Geographical location.
  • Potential water usage (if combining with Rainwater Harvesting).

Using the data provided above, our experts use Micro Drainage™ hydraulic modelling software to test the system and provide documentation ready for immediate submission to planning authorities.

Please call our sales team with the information above to allow us to specify the correct system on 01733 405 111.

Easy To Install

The F-line flat tank can be installed into much higher water tables than a standard round tank. If you don't know what your water table will be like in the winter, you're safer to install a flat tank.

The F-Line tanks are flat and the installation depth is 60% less than other rainwater tanks. The excavation can be up to 70% less, meaning little earth excavation, easy handling and less cost for you! The small excavation pit is easily filled in and your garden will look just like it did before.

F-Line Installation

What is a Gravity Feed System?

The rainwater is collected within the underground tank and then pumped up via the Rain Director's control unit to the smart header tank in the loft as and when required. From the header tank gravity is then used to take the water down to the appliances. When the toilet is flushed the level in the header tank will drop but will not fill up until a level sensor is triggered.

Mains water backup system

Rain Director House The Rain Director® pumps through a control unit, up to a "smart header tank" usually situated in a loft space. Inside the header tank are two level sensors, upper and lower. The system fills the header tank to the upper sensor then does not use the pump again until virtually all of the water is used and the lower sensor is reached. This "batch filling" process means the pump cycles 1-2 times per day, in comparison to every time a toilet is flushed with traditional systems. Coupled with the large reduction in energy and pump wear, the Rain Director® has numerous benefits in comparison to others on the market.

  • Full mains override, providing water in every eventuality: Low rainwater, pump failure or power cut.
  • Smart user functionality.
  • Ensures water quality by cycling water in the header tank if no activity is registered within 72 hours.
  • Three stage, electronic and physical overflow prevention system.
  • Cost effective and simple installation: push fit plumbing and image based installation guide.
  • Stylish and discreet control panel.
  • Fully WRAS approved. International Green Apple award winner, Waterwise approved, HBR Product innovation award winner.

What's in the kit?

Each system is supplied with the following components:

  • Required tank size
  • 635mm tank shaft
  • Pedestrian lid
  • Rain Active SuDS module inc overflow and siphon
  • Rain Director control unit and smart header tank
  • Hydroforce pressure sensitive pump
  • 25m of 25mm rainwater harvesting pipe
  • Rainwater Harvesting label pack
  • Micro Drainage™ calculations

Technical Details

Size 1500 3000 5000 7500
Weight Kg 80 170 250 310
Length 1200 2400 2960 3340
Width 2400 2400 2220 2310
Overall Height* 1015 - 1415 1015 - 1415 1350 - 1750 1415 - 1815
Ground to Invert** 335 - 735 335 - 735 335 - 735 330 - 730


Size 1500 3000 5000 7500
Length 1600 2800 3360 3740
Width 2800 2800 2620 2710
Overall Height* 1115 - 1515 1115 - 1515 1450 - 1850 1515 - 1915

*Overall height allows for 100mm compacted aggregate
**Using a VS60 (635mm Shaft)
The overall height difference above is because up to 400mm can be cut off the 635mm shaft on site so as to achieve your exact invert level.

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