1. Witteveen+Bos Consulting Engineers, PO Box 233, 7400AE Deventer, Netherlands
2. South-Holland East Water Supply (WZHO), PO Box 122, 2800 AC Gouda, Netherlands
3. Gelderland Water Supply (WGe), PO Box 15, 7000 AA Doetinchem, Netherlands
4. NUON Water, PO Box 400 (NUON), 8901 BE Leeuwarden, Netherlands
5. Water Supply Company of Midden Nederland Ltd (WMN), PO Box 40205, 3504 AA Utrecht, Netherlands
6. Overijssel Water Supply (WMO), PO Box 10005, 8000 GA Zwolle, Netherlands