he aim of this study was to observe the efficiency
of ozone transferred by an airstone bubble diffuser, us-
ing two ozone generators with different output of ozone
(5 g.h–1 ‒ G1; 15 g.h–1 ‒ G2). The retention of ozone in
ozonised distilled and potable water and the devitalisa-
tion effects on E. coli in the water were also noted. Ozone
was introduced to two types of potable water of differ-
ent composition intended for mass consumption, (MC)a
and (MC)b, distilled water, and well water intended for
individual consumption. The devitalisation effect of
ozone on E. coli in well water (WW) and added to pota-
ble and distilled water was observed. The results of our
study showed that under the conditions used, the level of
ozone during ozonisation with G1 increased more rap-
idly in distilled water and after termination of ozonisa-
tion, the retention of ozone in distilled water was a little
lower in comparison with the potable water. The devital-
isation of E. coli either naturally present in the water or
added to it required the level of ozone close to or equal
to 0.25 mg.l–1