Cold atmospheric plasma discharges in air above air–water surface interface and discharges inside water with injection of air bubbles, show interesting properties for water purification. Water parameters during plasma treatment get different values depending on discharge schemes. Detailed measurements of water parameters during plasma applications as pH, oxidation–reduction potential, total dissolved solids and conductivity are essential in understanding micropollutants degradation mechanisms in water. E. coli bacteria in water have been eliminated faster by plasma discharges produced in water than in air above it.