Measurement Entity

ORP

Oxidation-Reduction Potential — an electrical measurement of water's sanitizing capacity.

Definition

Oxidation-Reduction Potential (ORP) measures the water's ability to oxidize or sanitize — expressed in millivolts (mV). A higher ORP indicates greater sanitizing capacity. Unlike ppm-based chlorine testing, ORP directly measures chlorine's effectiveness considering both concentration and pH. The World Health Organization and many public health authorities specify a minimum ORP of 650 mV for swimming pools. ORP sensors are used in automated chemical control systems to maintain consistent sanitizing capacity regardless of bather load variations.

Quick Facts

Ideal Range
650–750 mV
Units
mV
Also Known As
ORP, oxidation-reduction potential, redox, sanitizing capacity

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