An in-line cleaning and sanitation apparatus for cleaning a liquid, the apparatus including electronic oxidation means to increase the oxidation reduction potential of the liquid, and ionization means to produce ions having an algaecidal or bactericidal effect into the liquid, in that order together with ultrasonic cleaning means to introduce sound waves into the liquid, and wherein the ionization means, the ultrasonic cleaning means and the electronic oxidation means are operated simultaneously for a period to clean and sanitize the liquid in the absence of added salt, chlorine or other chemicals.