| # | Company name | Role | # of projects |
|---|---|---|---|
| 1 | A. C. Vorwald & Sohn GmbH | Sanitary engineering | 1 |
| 2 | A. H. Water Planning Ltd. | Sanitary engineering | 6 |
| 3 | A. Papish & Co. Engineers Ltd. | Sanitary engineering | 37 |
| 4 | Ada Bronfman Engineers Ltd. | Sanitary engineering | 2 |
| 5 | Adler Bio- und Wassertechnik | Sanitary engineering | 0 |
| 6 | Ametyst - Wladyslaw Piechówka | Sanitary engineering | 1 |
| 7 | Aquatech (Offenburg) Consulting Engineers Ltd. | Sanitary engineering | 5 |