Conductivity of Water

Find out what the conductivity of water tells you about water quality.

Lab Summary

The conductivity of water is an indication of the quality of water, along with other factors, such as pH, turbidity, presence of microorganisms, presence of organic chemicals, etc. Measurement of the conductivity of water gives a quick indication of the total dissolved solids (TDS) in the water.

Students will use a conductivity sensor to explore factors that contribute to higher conductivity of water. They will investigate the cause of higher conductivity by comparing the conductivity of increasing amounts of ionic substances (table salt and soluble fertilizer) and a nonionic substance (sugar) dissolved in water. Finally, students will explore how nutrients from the soil, such as fertilizers, can enter adjacent water supplies. They will construct a watershed model and determine how the application of fertilizer to the soil of the watershed affects the conductivity of the runoff water.

Downloads

• Download Free Lab (PDF, 604 KB) (603 KB, .pdf)

  (student version)

Method

Use the pH and Conductivity Sensors to measure the pH and
conductivity of a variety of water samples.

Here's What You Need

U.S. Educator prices shown.

Probeware

PASPORT Conductivity Sensor (PS-2116A) - $110

Utilizes platinum probes for greater range and improved accuracy in high & low concentrations.

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Xplorer GLX (PS-2002) - $349

The Xplorer GLX is a data collection, graphing, and analysis tool designed for science students and educators.

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Other Materials

• Balance
• Watering can or squeeze water bottle
• Labels and Labeling Pens
• Clean plastic bottles with screw tops
• Beaker, 250-mL
• Spatula
• Large, flat, low-sided rectangular pan
• Protective Gear
• Weighing Paper
• Water, 2.0 L
• Soil or Sand sample, 2.0 kg
• Table Salt (NaCl), 1.5 g
• Water samples (from streams, etc.), 1.0 L ea
• Water, Distilled, 2.0 L
• Table Sugar (C₆H₁₂O₆), 1.5 g
• Soluble Fertilizer, 20.0 g