Water conductivity refers to its ability to conduct electricity, so it is also known as the electrical conductivity of water. 

The water available is sourced from various sources, and its conductivity varies accordingly. The presence of dissolved salts, minerals, and other tiny particles increases conductivity. 

For example, ocean water has higher conductivity and salinity than rainwater because it contains a lot of salts, while rainwater has very low conductivity because it lacks dissolved minerals.

Generally, the water conductivity ranges are measured to identify whether the water composition is suitable for a particular purpose, such as drinking and other domestic uses or industrial processes.

In this guide, you can get a better idea of the water conductivity range in various sources of water.

Why Is Water Conductivity Range Important?

Water conductivity indicates the quality and standard of the water. Water is a highly reactive substance, which means that it easily mixes with salts. This mixture increases the salinity of the water. If there are too many salts, the conductivity goes up, which can be harmful to fish and other aquatic animals. 

High conductivity can also be a sign of pollution from human activities like farming, factories, or sewage waste. So, checking the conductivity helps us understand if the water quality is safe for use and for the environment. It is usually measured in microSiemens per centimetre (μS/cm).

Read More About: Water Quality Sensors

Various Conductivity Ranges For Different Types Of Water

Water conductivity varies with the source. When the conductivity level of water exceeds the limit, it must be treated before being used for applications.

1. For Demineralised Water

The water conductivity ranges for demineralised water or demi water are 0.1–1.0 μS/cm. It is pure water, as a technical process has removed all minerals and salt. Due to the lack of minerals in this water, it is not suitable for drinking. 

However, it is important for some applications, such as the chemical and food industries, where boiler water, cooling water, or battery water is used.

2. For Reverse Osmosis Water

The water conductivity ranges in the reverse osmosis 10-100 μS/cm, depending on the quality of the source water and the RO system. 
Reverse osmosis is a water purification process that uses a semi-permeable membrane and pressure to remove contaminants like salts, organics, bacteria, and pyrogens.

Only clean water molecules pass through the membrane. RO water is safe and healthy for drinking, and the process is cost-effective for producing clean water for homes and industries.

3. For Drinking Water

There are no standards for the conductivity range for drinking water. But, according to the Environmental Protection Agency, the water conductivity should be less than 1000 μS/cm. This means that some dissolved minerals are good for human health. These minerals are calcium, magnesium, potassium, and more.

4. For Boiler Water

The water conductivity ranges for boiler water are between 2000 and 4000 μS/cm. The boiler is an essential piece of equipment that generates steam and is used in heating, power generation, and sterilisation industries. If the conductivity range increases from 4000 μS/cm, then it can lead to scaling or corrosion.

Scaling is a common problem for boiling water, clotting in piping, and heat transfer surfaces. During the heating process, the impurities, such as silica, iron, calcium, and more, settle out in the pipes or on the surface, resulting in boiler failure. 

Corrosion occurs due to dissolved oxygen and carbon dioxide. It increases the rate of decay or breakdown of the metals.

How Is Water Conductivity Measured?

Conductivity of the water can be measured using the electrode conductivity method. This method contains electrodes, a conductivity meter, and a probe (sensor). 

Here’s how it works:

• The probe contains two electrodes that are placed in the water sample.
  
• An electrical voltage is applied between these electrodes.
  
• As electricity flows, the dissolved ions (positive and negative) in the water move toward the respective electrodes.
  
• This ion movement creates an electric current.
  
• The conductivity sensor detects how easily this current flows through the water.
  
• The conductivity meter then displays the conductivity value, which reflects the concentration of dissolved salts and minerals.
  

The higher the number of dissolved ions, the higher the conductivity reading. This method is widely used because it provides quick and accurate results.

Other methods to measure water conductivity

1. Quick-Read Conductivity Paper

Quick-read conductivity paper is one of the simplest methods to measure the water conductivity value. It is a test paper that provides an approximate (not accurate) value of the water conductivity level. In this method, the paper classified the water conductivity according to the colours, like pH papers.

These papers have a short expiry time, so you need to use the papers before expiry. It is not suitable for those applications which need a long-term conductivity monitoring process.

2. Remote Sensing Measurement

Remote sensing measurement is used to address water conductivity without contact with the water. It is equipped with sensors that can connect with an aeroplane or a satellite. The range of measurement is wide. It measures the conductivity accurately, but the measurement result is affected by the colour of the water due to the high contamination.

Remote sensing measurements require high maintenance, so they are less commonly used in applications than other methods.

Conclusion

Water conductivity is affected by some factors, like dissolved ions, water temperature, and the presence of organic compounds. These can affect aquatic and human life. So, it’s necessary to measure the water conductivity ranges for various water sources to address the quantity of contamination in the water.

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