A machine for magnetic water treatment is designed and its application on the ions contained in water has been investigated to examine the effect of magnetic water on concrete parameters. Strength parameters of concrete have been studied for more than 104 concrete samples, including the non-magnetic samples (made by ordinary water) and magnetic samples (made by magnetic water), with slump and compressive strength experiments. Based on slump experiments, magnetic samples were 7 centimetres more than non-magnetic group and the average compressive strength of samples made by magnetic water was 23% more than that of samples made by ordinary water. The experimental results show the advantages of magnetic samples in concrete industry because of increase in plasticity, the efficiency and quality of concrete boosts in comparison with nonmagnetic samples. Key words: Magnetic water, compressive strength, slump, plasticity, surface tension decrease.