Vsaka pralnica naj bi imela napravo za ionsko izmenjavo, torej napravo za mehčanje vode. Med delovanjem ionskega izmenjevalca se na površini sintetičnih smol/polimerov nalagajo mikroorganizmi, ki se razmnožujejo in tvorijo biofilm. Ko biofilm doseže kritično točko, se iz njega pričnejo mikroorganizmi izpirati v mehko vodo. V primeru, da proizvedena mehka voda kaže povečano obremenitev z mikroorganizmi, govorimo o biološkem onesnaževanju. Zaradi tega moramo ionski izmenjevalec redno nadzirati. Rast mikroorganizmov na površini ionskega izmenjevalca preprečimo s kontinuiranim kloriranjem. Če ugotovimo nastanek biofilma, ionski izmenjevalec dezinfeciramo z ustreznimi dezinfekcijskimi sredstvi. Priporoča se uporaba peroksiocetne kisline, saj so raziskave pokazale, da peroksiocetna kislina že v zelo majhni koncentraciji in krajšem času učinkovanja povzroči uničenje nastalega biofilma. V raziskavi smo preverili kakovost mehčane vode, ki vstopa v postopek pranja v štirih pralnicah bolnišničnih tekstilij, da bi ugotovili, all je voda biološko onesnažena, kar zmanjša kemo-termični razkuževalni učinek postopka pranja. Rezultate smo primerjali s priporočenimi zahtevami za kakovostno nego in higieno tekstilij RAL-GZ 992/2 za bolnišnične tekstilije. Each laundry should have its own ion exchange device that is a water softening plant. During the function of ion exchange microorganisms settle on the outer surface of synthetic resins/polymers and multiply thus forming a biofilm. When the biofilm reaches a critical point, the microorganisms begin to flush into softened water. In that case when softened water displays an increased bioburden, biofouling occurs. Therefore, regular control of ion exchangers is necessary. The growth of microorganisms on the surface of ion exchangers is prevented by continual chlorination. In the case of discovering the presence of biofilm, the ion exchanger isto be disinfected by appropriate disinfecting agents. The use of peroxyacetic acid is recommended because the research has shown that small concentrations and short action times of peroxy acetic acid causes the biofilm to be inactivated. In the research we examined the quality of softened water for washing in four laundries for hospital textiles to determine whether biofouling, which decreases the chemo-thermal disinfecting effect of the washing procedure, has occurred. The results were compared to the recommended values for quality textile care and hygiene according to RAL-GZ 992/2 for hospital textiles.