WISY Storage Tank

  • Compression-resistant storage tanks
  • 4.5 m³ or 5.5 m³ storage volume l Manufactured without seams
  • Large access shaft
  • Smooth inside walls prevent buildup of deposits
  • Light weight
  • DN 100 tube bushings with seals
  • Non-slip cover
  • Vehicle-duty capacity with steel cover
  • Child safety device


Stable and leak-tight - guaranteed!

The WISY storage tank is optimally shaped to withstand vertical compressive loads. The rainwater storage tank is a seamless one-piece unit for long-term leak-tightness. We offer a 20-year guarantee on the durability of the environmentally friendly polyethylene tank material.

Thanks to their exceptional strength, WISY storage tanks with a steel cover are capable of withstanding the weight of passing road vehicles. This means that they can be installed under the driveway as well as in the garden. Even when weather conditions are wet, the non-slip cover is safe to walk over.

Perfectly hygienic

In contrast to the non-slip tank cover, the inside tank walls are perfectly smooth. This feature helps to prevent buildup of deposits and creates the best possible environment for maintaining water of optimum quality.

Child safety device (tested by German Technical Inspection Authority)

All WISY storage tanks come with a child safety device tested by the German Technical Inspection Authority (TÜV). This device protects children by preventing them from entering the tank unsupervised. The tank interior cannot be accessed without the use of tools.

Easy to handle on site

Thanks to their light weight and two rugged lifting eyes, WISY storage tanks are particularly easy to handle on site (using a mini-digger, for example). When the excavated pit is filled up with gravel the storage tank is fully supported from below. Tube bushings with fitted seals make installation even easier. For additional safety, a compressed water equalizing valve is fitted in the tank base for protection in the event of groundwater collection around the tank. The wide access shaft ensures ease of entry for maintenance work.

Equipment options

Basic equipment:

The WISY tank version with basic equipment includes the child safety device plus final ring made of high-quality stainless steel, two rugged lifting eyes and three DN 100 connection bores with seals. The tank is also supplied with either an aluminium cover or a vehicly-duty cover made of steel.


  • Child safety device
  • Final ring witn two lifting eyes
  • Cover made of aluminium or vehicle-duty steel
  • Compressed water equalizing valve in tank base

Complete equipment:

WISY tanks with complete equipment are supplied with the basic equipment mentioned above, as well as a vortex fine filter 100 (with the filter insert of the WFF 150), an overflow siphon with vermin guard, a backflow prevention device, and an inflow calming tube. The tanks are delivered with all components and tubing assembled ready for installation.

Includes (like basic, also with):

  • Vortex fine filter (WFF 100 with filter insert of WFF 150)
  • Multisiphon with vermin guard and backflow prevention device
  • Inflow calming tube made of stainless steel
  • System supplied ready to connect, all tubes and components assembled

Stormwater retention tanks:

WISY storm water retention tanks offer an additional retention volume with throttled outlet in addition to the useful volume for rainwater harvesting. The total tank volume is 5.5 m³ including a retention volume of between 1.5 and 2.5 m³. The retention volume and outlet must be selected according to urban land use planning guidelines.

Includes (like complete equipment, also with):

  • Retention volume 1,500, 2,000 or 2,500 litres
  • Floating suction coarse filter
  • Throttle to regulate volumetric flow rates

Technical Data

Sizes 4,5 m³ 5,5 m³
Diameter A 2.350 mm 2.350 mm
Tank height B 2.510 mm 2.770 mm
Service duct connection C 1.690 mm 1.950 mm
Drain connection D 1.285 mm 1.545 mm
Rainwater inlet E 1.895 mm 2.155 mm
Basic equipment 220 kg 250 kg
Complete equipment 250 kg 280 kg