The Sigma rainwater harvesting unit is the latest development from Germany‘s leading rainwater specialist WISY AG. With its neat, compact design, it is both quiet and efficient. Incorporating the energy saving Zeta controller, it has the lowest standby power consumption of any unit on the market. Better still, the Sigma unit is WRAS–approved, giving peace of mind for installers and owners alike. Two versions are available, depending on requirements. Combined with our shallow-dig Easy-Rain tanks, the Sigma-ER Domestic Rainwater Harvesting System offers a simple, elegant solution. To find out more download the Sigma-ER Brochure.