Abstract: In order to refine an admixing system (100) for admixing at least one extinguishing agent additive (32) to at least one extinguishing agent (22), having at least one extinguishing agent additive pump (34p1, 34p2, 34p3), particularly implemented as a component of or in the form of at least one dosing unit or at least one admixer (34), which mixes the extinguishing agent additive (32) into at least two extinguishing agent lines (26) using overpressure and which is connected to at least two watering or sprinkler units (10), in such a way that directly after the admixing system (100) is put into operation, without greater outlay, all watering or sprinkler units (10) have a mixture made of extinguishing agent (22) and extinguishing agent additive (32) available, it is suggested, that the extinguishing agent additive pump (34p1, 34p2, 34p3) be connected to each of the watering or sprinkler units (10) via at least one extinguishing agent additive line (36) in each case and that the particular extinguishing agen