Conductivity of Water

Last Updated : 15 Mar, 2024

Conductivity of water is the ability of water to conduct electricity or heat. It is measured using the symbols “s” or “k”. It is directly proportional to the number of conductive ions that are present in the water. Pure water has a very low conductivity as it doesn’t have any dissolved ions. On the other hand, natural water sources have different dissolved ions that increase their conductivity.

Let’s understand the conductivity of water in detail in this article.

Table of Content

What is Conductivity of Water?
Conductivity Formula
Conductivity of Saltwater
Use of Conductivity of Water for Industrial Applications
Thermal Conductivity of Water
Electrical Conductivity of Water
Factors Affecting the Conductivity of Water
Specific Conductance
Applications of Conductivity of Water

What is Conductivity of Water?

Conductivity of water reflects its ability to conduct electrical current. This ability is directly influenced by the concentration of conductive ions that are present inside the water. These ions stem from inorganic substances like carbonate, chlorides, sulphide compounds, dissolved salts, and alkalis.

Definition

Degree to which water conducts electricity is referred to as conductivity of water. It is denoted using ‘σ‘ and is the inverse of resistivity of the water.

Conductivity Formula

Formula for the conductivity of water is given as:

σ = 1/ρ

where,

σ is Conductivity of Water
ρ is Resistivity of Water

Units

There are various units used for measuring the conductivity of water. The table below can help us in understanding different units.

SI Units	Siemens per Meter [S/m]
US Units	Millimhos per Centimetre [mmho/cm]

Value of Conductivity of Water

Different types of water exhibit varying conductivity values. This can understand it through the table given below.

Types of Water	Conductivity
Rainwater	2 to 100 μS/cm
Pure water	0.05 μS/cm
Seawater	50 mS/cm
Drinking Water	200 to 800 μS/cm

Conductivity of Saltwater

When we mix salt in water, it disappears? That’s because the salt breaks down into tiny electrically charged particles called ions. There are positive ions (called cations) and negative ions (called anions).

Now, when we pass electricity through saltwater, these ions help conduct it. The positive ions are attracted to the negative side of the electrical source, and the negative ions are drawn towards the positive side. This movement of ions is what allows electricity to flow through the water. So basically, saltwater conducts electricity because these charged particles can move around and carry the electrical current.

Use of Conductivity of Water for Industrial Applications

Conductivity of water is important in Industrial applications because of the following reasons:

Equipment Protection: Protecting equipment is important in Industries. Conductivity monitors can show high or low levels of conductivity. High conductivity levels show that there are substances that can harm equipment. This information is helpful in the maintenance and protection of equipment.

Water Treatment: Conductivity measurements are used for monitoring the water treatment processes and It ensures that the quality of water meets the requirements.

Cost Savings: Conductivity monitoring helps in identifying and solving water quality problems and because of that money can be saved and this also prevents interruptions in industrial processes.

Environmental Compliance: Industries monitor and control the conductivity of wastewater through conductivity monitoring. It is done to follow environmental regulations and also helps in reducing their impact on the environment.

Thermal Conductivity of Water

Thermal conductivity of water refers to the ability of water to conduct heat. Compared to many other liquids, water is having relatively high thermal conductivity, which makes it useful in a variety of cooling applications. This is a result of the way that water molecules are structured and how they can form hydrogen bonds. Water has a higher thermal conductivity than many other common liquids, including oil and glycol, at about 0.6 W/mK.

Electrical Conductivity of Water

Electrical conductivity of water is the capacity of water to conduct electricity. It is determined by the presence of ions rather than the water itself. Conductivity is increased when there are more ions from impurities, dissolved substances, or temperature.

Conductivity help in the assessment of water purity and quality. Pure water is a weak conductor, while potable water is a great conductor of electricity.

Factors Affecting the Conductivity of Water

The conductivity of water is influenced by several factors which are as follows:

Concentration of Ions: The presence of ions in a solution changes its conductivity. When there are more ions present, the conductivity of water increases.
Type of Substance: The conductivity of the water might vary depending on the type of substance dissolved in it.
Mineral Purity: Mineral purity is also another factor that can affect conductivity. When minerals are added as a pollutant in the water, then it is seen that ionic bonds of water molecules have conducted electricity and hence, there is an increase in the electrolytic conductivity of water.
Temperature: The conductivity of water depends on its temperature because electrical conductivity increases as temperature rises.

Specific Conductance

The conductivity of an object measured under standard condition is called the specific conductance. Specific conductance is the conductivity of water at 25°C. Pure water, without any dissolved ions, is a poor conductor of electricity. However, natural water sources typically contain various dissolved substances, making them more conductive.

Specific conductance is usually measured in units of Siemens per meter (S/m) or microsiemens per centimeter (µS/cm).

Applications of Conductivity of Water

There are various practical applications of the conductivity of water. Here are some of the key applications:

Water Quality Monitoring: Conductivity is a great indicator of water quality because it can detect dissolved ions and pollutants. It helps in identifying changes in water quality over time and it also evaluates the effectiveness of water treatment.

Industrial Processes: Monitoring conductivity is important in industries like power generation, pharmaceuticals, and food. This helps in ensuring product quality and process efficiency. High conductivity levels indicate impurities that can impact the quality of the product or the performance of equipment.

Environmental Monitoring: Conductivity measurements are also used to evaluate the health of aquatic ecosystems in environmental monitoring programs. Here, changes in conductivity can indicate pollution or environmental disruptions that impact aquatic life.

Agriculture: Monitoring the conductivity of irrigation water is important for keeping the right balance of nutrients in the soil. Where there is a high level of conductivity, it shows that there is too much salt which can harm crops.
Aquaculture: Water conductivity is monitored in aquaculture to make sure the water is suitable for fish and other water creatures. High conductivity levels indicate that harmful substances are present in that water that can harm aquatic life.