Water Resistivity (RES) Sensor

What is Resistivity (RES)?

Resistivity in water is the measure of the ability of water to resist an electrical current, which is directly related to the amount of dissolved salt in the water. Water with a high concentration of dissolved salts will have a low resistivity, and vice versa. Resistivity is measured in Ohms.

Aquaread RES Sensor

Aquaread’s RES measurement is directly measured using the electrical conductivity (EC) sensor, in fact, RES is the inverse of the of EC. RES is the waters ability to resist electrical current and is linked to the amount of dissolved salts within the water.


Key Features

  • Parameter that’s always included on every Aquaprobe and Aquasonde.
  • Uses the Corrosion resistant gold coated stainless-steel EC sensor.
  • Measurement range 5Ohm/cm – 1MOhm/cm
  • Resolution 2 auto ranging scales: 5 – 9999Ohm/cm, 10.00 – 100.00Ohm/cm.
  • Accuracy of 1% of reading.
  • Requires no calibration – this is taken care of when you calibrate the EC sensor.

Our RES sensors come as standard on many of our probes, below are some examples.

To see all of the probes that feature RES please visit the Products section.



Advanced portable multi-parameter Aquaprobe.

AP-700 & AP-800

AP-700 & AP-800

Basic Water Monitoring Packages



The Aquasonde-2000 has 2 spare ports. They can house either 1x ISE sensor and 1x Optical sensor. Or it can house 2x ISE sensor.

Always included

The RES parameter is included on every Aquaprobe and Aquasonde, it is also included in the AquaPlus optical dissolved oxygen sensor.