Storm Water Retention Tank

  • Dual use as rainwater storage tank and retention tank
  • Retention volumes 1500l, 2000l und 2500l available
  • All components preassembled ready to install
  • Vehicle-duty design
  • Seamless one-piece tank: 20-year guarantee


Retention of stormwater

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.


  • Retention volume 1,500, 2,000 or 2,500 litres
  • Throttle to regulate volumetric flow rates with floating suction coarse filter
  • 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
  • Final ring witn two lifting eyes
  • Cover made of aluminium or vehicle-duty steel
  • Compressed water equalizing valve in tank base

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.

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.

Technical Data

Total volume 5.5 m³
Diameter A 2,350 mm
Tank height B 2,770 mm
Service duct connection C 1,950 mm
Storm drain connection D 750
Rainwater inlet E 2,155 mm