CP Design Center

Resistance and Resistivity

Approximate Resistivity of Water

T is ppm dissolved solids
R is resistance in ohm-cm.

Resistance of a Single Rod Anode to Earth(1)

Resistance of Multiple Vertical Anodes to Earth(1)

(1)Derived from H.B. Dwight Equations

Rough Indications of Electrolyte Corrosivity vs. Resistivity

Ohm - Cm Corrosivity
Below 100 Extremely corrosive
100 - 1,000 Very corrosive
1,000 - 2,500 Corrosive
2,500 - 7,500 Moderately corrosive
7,500 - 15,000 Mildly corrosive
Over 15,000 Progressively less corrosive