ORP can be a valuable measurement if the user knows a particular component within the sample that is primarily responsible for the observed reading. High pH ionized water demonstrates a –ORP and so is a reducing agent or “antioxidant”. High pH ionized water demonstrates a –ORP and so is a reducing agent or “antioxidant”. But disinfection capability of chlorine is also pH dependent so pH has to be measured. Drinking water is adequately disinfected at an ORP of 650 mV. For chlorinated pools and spas, a safe ORP reading is usually between 650 millivolts (mV) and 750 mV. Most water has a positive ORP reading, so it is oxidizing. Measuring ORP: Tips, Cautions and Limitations. Measuring ORP: Tips, Cautions and Limitations. Japanese research states that the ideal range for drinking alkaline water is between pH8.5 and pH9.5. Alkaline water typically has a pH of 8 or 9. Other sources suggest a chlorine level of 3-5, which on my pool/sensor seems to correspond to an ORP level of about 590. The ORP of most tap water in North America is between +200 to +600mv, ie. Sometimes ORP is used as a measure of oxidizing power in the water rather than measuring the chlorine level. For example, water may be moderately oxidizing (such as aerated water), strongly oxidizing (such as chlorinated water or hydrogen peroxide solution), or reducing (such as an environment where anaerobic microbes are active). Alkaline ionized water has an ORP of -350 to -800, depending in part on the amount of minerals in the source water and how the ionizer is adjusted. Bottled water tends to have high ORP levels of more than +400mv. The ORP of most tap water in North America is between +200 to +600mv, ie. Is it reverse osmosis? Even tap water has a high ORP even though it is required by law to have a neutral pH level. Studies on specific micro-organisms have found a direct correlation between increasing ORP and micro-organism inactivation as shown in Graph 6.1. HOWS THE OXYGEN LEVELS IN YOUR DRINKING WATER? ORP measurement s are used to control disinfection with chlorine or chlorine dioxide in cooling towers, swimming pools, portable water supplies and other water analysis applications. Research shows that the ideal level for drinking alkaline water is between pH8.5 and pH9.5, with an ORP of -250mv. Alkaline ionized water is different because it has a negative ORP reading, making it anti-oxidizing. In the disinfection of drinking water, an ORP value of 0 mV is required for oocyst inactivation. Though ORP is classically based on a standard hydrogen electrode (SHE) as a reference, practical limitations to this approach cause most commercial ORP sensors to use an Ag/AgCl reference. Another good example is in chlorine disinfection. ORP is measured in millivolts (mV) using an ORP meter. Water with an ORP of -50mV will have enough negative ions to attract and neutralize excess acids Drinking water should have a … The ORP of most tap water in North America is between +200 to +600mv, ie. High pH ionized water demonstrates a –ORP and so is a reducing agent or “antioxidant”. these waters are oxidizing agents.