ORP stands for oxygen reduction potential. It’s all about the energy stored in the system ready for usage. When it comes to water ionizers, it talks about the energy stored in the form of millivolts. It is usually measured by the use of an ORP meter. It is used to measure the negligible voltage found in water that determines the amount of reducing and oxidizing agents inside the water. Ionized water is known to be extra good for human consumption as it boasts of -250 mv ORP or even less. The best negative ORP indicates the existence of hydrogen molecules, which are useful antioxidants good for eradicating acid toxins.