In 2000 the full-scale membrane filtration plant for Artis Zoo in Amsterdam will start operation. The plant con-sists of an ultrafiltration system, design capacity 50 m(3)/h, and a reverse osmosis installation, product water capacity 18 m(3)/h. In the Artis Zoo, a lot of water is used for cleaning cages and refreshing the ponds. Already in the early nineties Artis Zoo started looking for alternative water sources in order to reduce costs for drinking water. In 1997 the idea originated to recirculate and clean water in the Zoo for reuse, and the engineering companies Geam and DHV Water started feasibility studies on this subject. During the study a second item came into the picture: the use of Amsterdam canal water as supplement water. In October 1999, pilot trials were carried out on the UF membranes, followed by detailed engineering in which for example the limited available area for the water treatment plant had to be accounted for. In the autumn of 2000 the building of the unit will start, leading to start up of the plant around the Ist of October 2000. An ultrafiltration unit performs the main treatment of the recirculation water. To com-pensate for water losses, supplement of water is necessary. To complete the thought of water reuse, the idea came to use canal water as supplement. In order to prevent accumulation of salts, an RO system is needed which will operate on a by-pass stream of the UF product water. Main feature of the RO system is the use of low fouling membranes. The ultrafiltration membranes are 1.5 mm capillary membranes, supplied by membrane manufacturer Stork Friesland The system design is based on an average flux of 50 1/m(2)/h Periodic cleaning with air-scouring lair flush) will be applied. Field results on other full-scale UF plants show that with air flush membrane cleaning is much more effective, leading to longer interval periods between cleaning and a high reduction in cleaning chemicals and thus higher recovery of the system and lower costs per m(3) of permeate.