The invention relates to a device for preparing aqueous solutions intended to be sprayed via a manifold including two or more nozzle sections, on a surface from a mixture of water and two or more additives. Said device includes: —a water vessel (2) —a pump (6) connected to each section (4, 5) —a first pipe (8) connecting the water vessel (2) to the pump (6) —a second pipe (9) with as many parallel arms between the pump (6) and each section (4, 5) —at least two additive vessels (10, 11) and—a means (12) for metering the amount of each additive that is to be injected into the second pipe (9) and mixed with the water.
