A glass being filled with water.

How to Check Water Quality Using CN0428

What is Contaminated Water?

Contaminated water typically contains harmful bacteria, protozoa, viruses, and parasites, chemicals such as bleach, pesticides, nitrogen, arsenic, toxins produced by bacteria, and heavy metals like iron, which are carried by rain and corrosion. It muddies the water and makes it taste unpalatable. Arsenic, which exists in nature as a trace material in rocks and sediment copper enters water supplies primarily through pipes and home fixtures like lead, which is a toxic metal to ingest, especially for children.

The CN0428 is a system that can be used to demonstrate the measurement of the quality of water. It uses the electrochemical impedance spectroscopy technique to detect the presence and quantity of these harmful contaminants in water.

Why is Water the Elixir of Life?

Water has the following unique qualities that make it a crucial resource for plants, animals, and human beings. Water is a very good solvent – it can dissolve many substances. The boiling point and freezing point of water make it easily available in all three states (solid, liquid, and gaseous). The specific heat of water is quite high. This enables water to absorb and release heat slowly, thereby regulating the temperature of its environment. Owing to its transparency, water can allow light to reach the life forms that are submerged in it. This is crucial for the survival of plant life in the oceans, lakes, and rivers. Water is neither acidic nor basic in nature. It has a pH of 7, making it a neutral substance.

These unique qualities get modified or disturbed when water contains contaminants. Identifying them and taking appropriate actions to restore the goodness of water is crucial to help sustain a healthy ecosystem.

What is CN0428?

It is a system capable of measuring the pH, Conductivity, Temperature, and ORP of a solution. The board can be configured for customized measurements such as Dissolved Oxygen (DO) measurement, Ion Concentration measurement, i.e., Ion Selective Electrode (ISE) measurement, and many other water quality factors. Up to 4 sensor boards can be connected for measurements simultaneously.

Given below is the block diagram of the water quality measurement setup using CN0428:

 block diagram of the water quality measurement setup using CN0428

CN0428 contains EVAL-CN0428-EBZ, the EVAL-M355-ARDZ-INT, and the Arduino Uno board as a system.

Below is a picture of the CN0428 system:

  CN0428 system


 The following analog-output 2-electrode probes are typically used for measurement:

  • Cole-Parmer 100-series Replacement pH/Temperature Electrode
  • Cole-Parmer 100-series Replacement Conductivity/Temperature Probe, K=1
  • Sensorex S550C-ORP Heavy-Duty ORP Sensor


The below items are used for demonstrating water quality measurement using CN0428:


  • Arduino Uno
  • EVAL-M355-ARDZ-INT Arduino-compatible platform.
  • EVAL-CN0428-EBZ Water Quality Sensor Board loaded with firmware. (1 no.)
  • BNC Connectorized probe. (4 nos.)
  • Type B to Type A USB cable
  • PC or Laptop with a USB port


  • CN0428_example sketch
  • Arduino Interactive Development Environment (IDE)
  • Arduino AVR Boards Built-In by Arduino package (1.6.23)

 Which Parameters Decide Water Quality?

Desired Measurement



pH - Wikipedia


Reduction potential - Wikipedia


Conductivity (electrolytic) - Wikipedia


Time to see the results!

pH Level measurement:

Sample: Bottled water

 pH Level measurement

 Alkalinity Chart

Conductivity Measurement:

Sample: Bottled water

  Conductivity Measurement

 Conductivity of water in different types of water

ORP Measurement:

Sample: Tap water

  ORP Measurement Oxidation Reduction Potential


Learnings and Takeaway

Water quality monitoring and maintenance are important in our seas, our rivers, on the surface, and in our ports, for both companies and the public. It enables us to assess how they are changing, analyze trends, and inform plans and strategies that improve water quality and ensure that water meets its designated use. The pH level, ORP, and conductivity of water are measures of its quality. CN0428 system is developed to accurately measure the above parameters of water.


CN0428 Circuit Note | Analog Devices

ADUCM355 Datasheet and Product Info | Analog Devices