How Do You Measure Turbidity In Water?

This is actually a relatively simple and straightforward process in the modern world. In the past, people really could only do so much in order to get a sense of the turbidity of water.

Today, it is still easier to answer the question: how do you measure turbidity in water? Still, people should take into account the subjective and objective aspects of trying to measure turbidity. There are still challenges associated with measuring turbidity in water.

Earlier Methods of Measuring Turbidity

Turbidity is a function of the dissolved particles in water and the color of the water. Clean water is transparent, so water that has any coloration is contaminated with something in all cases. The dissolved particles will typically be sand, algae, or clay, but there could be variations. The turbidity of water once had to be measured in a purely qualitative sense.

People would just try to rate the turbidity levels of a given quantity of water in a purely subjective manner. Most people tended to avoid water with an apparently high turbidity level, even though turbid water is not necessarily as dangerous as people might think.

There are turbidity meters and turbidity sensors that people can use today. These tools will tend to make the process of measuring turbidity relatively simple. The water quality monitoring professionals will just have to make sure that they are using the tools correctly.

Some aspects of measuring turbidity in water are subjective. The units that are used to quantify the turbidity levels in a body of water are technically subjective in their own right. The designs of different instruments can have an effect on the turbidity levels that will be recorded between measurements. However, it is still possible to get usable turbidity data.

Turbidity Meters

Most turbidity meters make use of 90 degree scattering. They might use some different optical scatter-detection techniques, but many of their techniques fall into this category. These techniques sound advanced, but there were versions of them around in the 1980’s. The technical term for these techniques is ‘nephelometry.’

Essentially, with nephelometry, a laser beam gets directed through a sample. When this happens, the particles in the sample will deflect some of the incoming light. This forwarded scattered light is easy enough to measure that it can grant accurate readings. The sample will typically be a sample of water, but people can use all of these techniques on all liquid samples.

Light scattering makes it much easier to detect imperfections, variations, and irregularities that are very small. The particles are still large enough to be affected by light and to deflect it, and the scattering will make them more visible indirectly. The optical scatter-detection techniques can be used to calculate the turbidity of a water sample very quickly and accurately.

One of the limitations associated with using turbidity meters is the simple fact that people will need to use them to test water samples only. People cannot place one of these laser beams throughout an entire water source. They will need to make an estimation about the quality of an entire water source based on the samples that they test.

While scientists and water quality monitoring professionals will typically test multiple water samples at a site, they will still only be able to test a limited number of them. From there, they will have to extrapolate. It is true that the turbidity of one sample will tend to be similar to the turbidity of another sample, so the margin for error might be smaller than people think. Still, some water sources can flow according to strange patterns. Technically, nephelometry can only be used to test the turbidity of a water sample.

In many cases, nephelometry also causes problems because people will only be able to test the water samples at any given point. It is possible that the turbidity of a body of water is going to change with time. However, people will not necessarily know that this is the case unless they take multiple samples over an extended period of time. This can work and this can help scientists get around some of the basic issues with nephelometry. However, this still means that continuous water quality monitoring will prove to be unsuccessful.

Scientists and water quality monitoring professionals will use nephelometry and it is certainly a great method. However, it is still important to keep some of its limitations in mind.

Turbidity Sensors

Turbidity sensors are similar to turbidity meters in a lot of ways. These tools will both use optics to their advantage. However, one of the great advantages of turbidity sensors is the simple fact that it is possible to truly test the turbidity of an entire water source using them.

Water quality monitoring professionals and scientists will just need to position the turbidity sensors in the water source and they will be able to make progress when it comes to getting an accurate read on the turbidity of the water.

One of the other advantages of turbidity sensors is that they can be used to get a sense of the turbidity of a water source over time. With the repetitive and constant measurements that people will get with these sensors, it will be that much easier for people to be able to genuinely assess the water quality in an area.