Water Turbidity Measurement: A Comprehensive Guide for Industry and Drinking Water

Measuring Water Turbidity

Have you ever wondered why tap water should be completely clear? Or why in various industries, even a speck of turbidity in water can cause billions in damages?

The answer to these questions lies in a concept called "water turbidity". Turbidity is not just an apparent problem; it is also a key indicator for health, efficiency and safety in many industrial and water supply processes.

In this article, you will learn in a completely comprehensive and practical way about the concept of water turbidity, its causes, measurement methods, global standards, its negative effects on industrial equipment and ways to reduce it.

What is water turbidity?

Turbidity is a measure of water clarity. The turbider the water, the less light passes through it. This phenomenon occurs due to the presence of suspended particles in water that are not visible to the naked eye, but scatter or absorb light.

These particles can include:

• Soil and clay
• Sludge and organic sediments
• Algae and microorganisms
• Metal particles or chemicals
• Particles from pipe erosion

Why is measuring water turbidity important?

Turbidity is not just an aesthetic indicator. In fact, this parameter plays a vital role in the following:

1. Public health

In drinking water, high turbidity can be an indication of the presence of bacteria, viruses or parasites. Suspended particles can act as a haven for pathogenic microbes and reduce the effectiveness of disinfection methods such as chlorination.

2. Efficiency of industrial processes

In industries such as power plants, heating plants, cooling systems and boilers, high turbidity leads to:

• Formation of deposits on the internal surfaces of pipes and heat exchangers
• Reduced heat transfer
• Increased energy consumption
• Corrosion of equipment

3. Compliance with standards

International organizations such as the World Health Organization (WHO) and national standards (such as the Iranian National Standard 1053) have set the maximum permissible turbidity level in drinking water between 0.5 and 1 NTU.

Factors causing turbidity in water

Turbidity can be caused by natural sources or human activities:

• Heavy rainfall: causes soil erosion and the entry of particles into surface water sources.
• Agricultural activities: The use of fertilizers and irrigation can transfer fine particles into rivers.
• Industrial effluents: Some industries return turbid water to the environment without adequate treatment.
• Erosion of old pipes: In urban water supply systems, rust and decay of pipes introduce metal particles into the water.

Methods for measuring water turbidity

Turbidity is measured accurately and in a standardized manner. The most common methods are:

Nephelometric Method

This method is the international standard and is based on light scattering at a 90-degree angle. The device used is called a turbidimeter.

• Unit of measurement: NTU (Nephelometric Turbidity Unit)
• High accuracy, suitable for laboratories and industry

Jackson Candle Method

An older method that uses a candle and a glass tube to measure the depth at which the candlelight is not visible.

• Unit: JTU (Jackson Turbidity Unit)
• Less used today

Other methods

• Formazin method: Using a standard Formazin solution to calibrate devices
• Optical method with smart sensors: In industrial online monitoring systems

Turbidimeter for accurate measurement of water turbidity

International and national standards for water turbidity

Note: In industrial water circulation systems (such as cooling towers), even turbidities below 1 NTU can lead to long-term scaling.

Impact of high turbidity on industrial equipment

In industries where water is used as a heat transfer or coolant, high turbidity can cause serious damage:

1. Scaling

Suspended particles gradually settle on the inner surfaces of pipes and exchangers, creating an insulating layer that impairs heat transfer.

2. Increased energy consumption

With reduced heat transfer, systems consume more energy to reach the desired temperature — sometimes by as much as 15 to 20 percent!

3. Under-deposit Corrosion

Deposits can create an acidic or oxygen-deficient environment that causes localized corrosion of metals.

4. Clogging of nozzles and filters

In spray or cooling systems, small particles can clog nozzles and impair system performance.

Ways to Reduce Water Turbidity

Reducing turbidity requires a systematic approach. Common methods include:

1. Coagulation & Flocculation

• Adding chemicals such as alum or polyelectrolytes
• Fine particles become larger and settle more easily

2. Sedimentation

• Flocculated particles settle in tanks due to their greater weight

3. Filtration

• Using sand filters, cartridges, or membranes (such as RO)
• Is effective for removing very fine particles

4. Using online monitoring systems

• Installing turbidity sensors in main lines for early warning

5. Periodic chemical flushing

• In industrial systems, using specialized solutions to clean sediment and accumulated particles

Some chemical washing projects by Abrizan

Water turbidity reduction process by flocculation and sedimentation

❓❓❓ Common questions from users about water turbidity ❓❓❓

❓ Is turbid water necessarily contaminated?

Not necessarily. Sometimes air bubbles or dissolved carbonates cause temporary turbidity that disappears after a few minutes. But if the turbidity is persistent, it needs to be investigated.

❓ Do home filters reduce turbidity?

Yes, activated carbon filters or micron cartridges (1 to 5 microns) can remove some of the particles, but for high turbidities, more advanced systems such as RO are needed.

❓ When should water turbidity be measured?

• At the inlet and outlet of treatment plants
• Before and after chemical processes
• In industrial systems: monthly or seasonally
• In case of a change in the color or smell of the water

✅ Conclusion: Water turbidity, a small indicator with a big impact

Water turbidity is not just a number in a laboratory report; Rather, it is a vital indicator of the health, efficiency, and sustainability of water systems. Whether at home or in industry, ignoring this parameter can lead to heavy costs — from increased energy consumption to expensive equipment failure.

If you operate in industry and use water circulation systems, regular turbidity checks and specialized water tests can extend the life of your equipment and prevent damage. Also, if you need detailed water analysis or design chemical maintenance programs, consulting with experts from reputable laboratories can make your decisions smarter.

✅ Our suggestion: Test the water in your industrial systems for turbidity and other key parameters (such as hardness, pH, TDS) every 3 to 6 months.

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