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.

RainSava below ground
Simple, effective and ultra clean water!
Use Me For
watering can
car washing
Garden rainwater harvesting
  • Below Ground Storage tank
  • Cleanest water possible due to the Wisy® 4-step system:
    Class-leading pre-tank filtration to 0.28mm.
  • Advanced Vortex filter removes debris whilst oxygenating the water. The vertical construction avoids debris degrading on a horizontal filter mesh.
  • Stainless steel calmed inlet for stable sedimentation and oxygenation.
  • Fine suction filter with 0.3mm mesh extracts water from the cleanest part of the tank
  • Multi-functional overflow unit with deep water trap and anti-backflow device
  • Automatic start/stop pump
    • 46m head
    • 95L/min flow rate
BS8518 Compliant Rainwater systems
BS8518 Compliant
Easy to clean filter
Easy to Clean
0.2mm Fine Mesh Filter
0.28mm Mesh Filter

Storing water for garden use in an underground tank is ideal. Whilst it requires more work initially to install, it does mean that the tank is out of the way and out of sight. The cool, dark environment keeps the stored water fresh and clean for longer, and maintains a stable temperature.

As with all our rainwater harvesting garden systems, rainwater is filtered prior to reaching the tank using our advanced Vortex filter that not only remove debris and fine particles, but also improves water quality through oxygenation.

Once stored, a submersible pump delivers the water to taps around the garden. The system can be used for drip irrigation with the addition of a pressure vessel ,and an upgrade of pump can accommodate sprinklers. The pump is automatic, turning on and off upon demand.

Looking after the Rainsava Below Ground rainwater harvesting garden system is easy, as the leaf filter is sited before the tank rather than within it, and is accessible from ground level.

RainSava® GRP 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 RainSava® tanks are always fitted with backflow protection.

Tank Volume (Litres)Nominal length (mm)Nominal diameter (mm)Weight (kg)
15001600122090
200021001220130
240023501220150
300020001520180
350023001520190
400026001520200
500030801670240
600027001840260
750033501840300

Other sizes are available, including large tanks for commercial projects up to 100,000 litres.

NB. All GRP tanks are built to order with the ability to have the inlet invert as deep as 1.2m, but can be made to accommodate greater depths if necessary. Before ordering a tank, check what depth your inlet will be to make sure the tank is correct for your installation. Tank necks can always be cut down on site if needed.

HINT: It is good to be shallow with the tank, but the pipe depth is governed by the location of the tank and distance the pipes have traveled in the ground rather than the type of tank. Most UK water pipes are buried at 600-900mm.

Low Profile Shallow-Dig Tanks

In some situations it may be desirable or beneficial to use a shallow tank (e.g. in high groundwater conditions or hard rock ground). For these installations we offer a range of low-profile tanks. These are excellent for certain situations, but are manufactured from a costlier material and imported from Germany so are naturally more expensive.

Also note that these tanks do not include backflow protection, unlike our GRP tanks.

Tank Volume (Litres)Nominal length (mm)Nominal width (mm)Nominal height (mm)Weight (kg)
15002400120073580
300024002400735160
5000296022201035250
7500334023101240310

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.