Tech Insights

What is turbidity

Nov 14, 2025·Official source

Puzzle-solving class: How to quantify the "clarity" of water? One article to understand the past and present life of turbidity

When you evaluate whether a glass of water is clean, what is the first indicator you use? The answer is often - "Does it look clear?" This most intuitive visual experience is quantified by a precise parameter called turbidity in the fields of environmental monitoring and water treatment. Today, let us uncover the mystery of turbidity and see how we set standards for “clearness”.

1. What is turbidity? Beyond the scientific definition of vision

Simply put, turbidity is a measure of how much suspended particulate matter in a body of water blocks the passage of light. These suspended particles may include sediment, clay, organic matter, plankton, bacteria, etc.

We can make a vivid metaphor:

Clear mountain spring water is like a piece of transparent glass, light can pass through unimpeded and the turbidity is extremely low.
The turbid Yellow River water is like a piece of "frosted glass". Light is scattered and absorbed by countless tiny particles when passing through it, causing the light transmittance of the water to decrease, making it look turbid and with high turbidity.

Therefore, turbidity is a comprehensive physical indicator, which directly reflects the apparent clarity of the water body. It is one of the most intuitive and rapid parameters for judging the quality of water.

2. Why should we monitor turbidity? It doesn't just "look dirty"

The significance of monitoring turbidity goes far beyond aesthetics. It is also a vital water quality safety and process control indicator.

"Sentinel" for Drinking Water Safety Many harmful microorganisms (such as bacteria and viruses) in water are tiny and difficult to detect directly, but they often adhere to suspended particles. High turbidity means more pathogens may be hiding in the water. Therefore, in the water plant treatment process, strict control of effluent turbidity is a key line of defense to ensure the microbial safety of drinking water.
The "baton" of water treatment technology In water treatment units such as coagulation, sedimentation, and filtration, turbidity is the core parameter for evaluating treatment effects. By monitoring the turbidity changes before and after each process link in real time, operators can accurately adjust the dosage of chemicals and optimize operating parameters, thereby ensuring treatment efficiency and reducing operating costs.
"Health indicators" of environmental water bodies For surface waters such as rivers and lakes, abnormal increases in turbidity may indicate environmental problems such as soil erosion, sewage discharge, or algae outbreaks, and are important early warning indicators for environmental monitoring.

3. How to accurately measure turbidity? The "game" of light and particles

Modern online turbidity sensors are mainly based on the principle of light scattering, which is far more precise than the rough judgment of the human eye. The core principle is that when a beam of light passes through a water sample, suspended particles in the water scatter it in all directions.

According to different detection angles, it is mainly divided into several methods. Among them, the 90° scattered light method is an internationally recognized standard method because it is less affected by particle size and color interference and has the highest accuracy.

The working principle of our turbidity sensor is based on this:

The luminescence inside the sensor emits a stable beam of specific wavelength.
The light beam passes through the water sample to be measured, and the suspended particles in the water scatter part of the light in the 90° direction.
A photodetector positioned at 90° receives this scattered light and converts it into an electrical signal.
After the signal is processed, an accurate turbidity value is calculated based on a calibration curve between the intensity of scattered light and turbidity.

This optical principle ensures high accuracy and continuity of measurement, which is far better than the traditional manual visual turbidimetry method.

4. Units of turbidity: the world of NTU

Turbidity has its own specific unit of measurement. Currently the most widely used is NTU. This means that when you see our sensor data showing 0.3499 NTU, you have an accurate quantitative idea of how clear the water is.

5. Wide application scenarios of turbidity sensors

YuanGan Technology's online turbidity sensor plays an irreplaceable role in the following fields because of its continuous and accurate characteristics:

Drinking water treatment plant: Real-time monitoring of the turbidity of raw water, precipitated effluent, filtered water and factory water.
Industrial process water: Monitor the purity of boiler feed water, electronic ultrapure water, and beverage production water.
Sewage treatment plant: Evaluate the clarity of the final discharge water to ensure that it meets discharge standards.
Aquaculture: Monitor the aquaculture water environment to avoid excessive turbidity affecting the health of aquatic organisms.
River and lake monitoring: Construct an online monitoring network to provide data support for environmental protection.

Conclusion

Turbidity, this seemingly simple parameter, is actually a bridge between sensory judgment and scientific quantification. It is the cornerstone of ensuring water quality safety and optimizing water treatment processes.

As an expert in the field of water quality analysis, each turbidity sensor and online instrument provided by YuanGan Technology integrates advanced optical systems, sophisticated algorithms and reliable Modbus communication capabilities. We are committed to not only providing you with a reading, but also providing you with an accurate and trustworthy report on water clarity, helping you better protect the clarity and safety of every drop of water.

——YuanGan Technology, the water quality sensing expert around you