Tombal-brasses with impurities such as Ni, Fe, Sri and Al, together with Bi and Se are the most inexpensive raw materials used in the manufacturing of plumbing and faucets, as replacement for the traditional Pb-bearing tombal brasses. The present paper deals with the segregation of those impurity elements and their effects upon addition of phosphorus and arsenic. Phosphorus and arsenic are normally considered as retardant elements in the dezincification process observed in brasses. However, the operating mechanism has not been totally resolved. This work describes the interaction of phosphorus and arsenic with the impurities contained in this type of brasses, concluding that the main effect results upon the combination of the impurities with Fe or Al or both, allowing for cleaning of the beta-phase, which is most susceptible to dezincification.