The invention relates to a device for treating urea-containing water. The invention also relates to a domestic toilet provided with such a device. The invention also relates to an animal accommodation provided with such a device. In addition, the invention comprises a method for treating urea-containing water. The device comprises a nitrification unit adapted to oxidize urea to nitrates and carbon dioxide, wherein the nitrification unit is also provided with an oxygen feed, a gas discharge and a throughfeed for feed of waste water nitrified by the nitrification unit to a filtration unit connected to the nitrification unit. The nitrification unit preferably comprises nitrifying bacteria.
