
| Taprogge Watertech GmbH | since 2002 | ||
| Emerald Cleantech Fund I LP | since 2004 | ||
| Sustainable Performance Group (Unlisted) N.V. (SPG) | since 2004 | ||
| Siemens Venture Capital GmbH (SVC) | since 2004 | ||
| StoneFund N.V | since 2006 | ||
| Entrepreneurs Fund LP | since 2007 | ||
| BayTech Venture Capital GmbH | since 2009 |