Evaluating the 3 Ts of Solid Matter for Water Quality Analysis with LIMS for Water & Wastewater Testing

LIMS for Water & Wastewater Testing Evaluate Solid Matter for Water Quality

Solids in water can be a nuisance. Excessive solids can degrade the water’s visual quality and suitability for drinking, and limit recreational activities like swimming, boating, and fishing. This can have negative economic impacts on communities that rely on tourism and water-based industries. But more than that, certain dissolved solids, like heavy metals, can accumulate in aquatic organisms over time through a process called bioaccumulation. This can lead to serious health issues in aquatic life and the animals (including humans) that consume them. A Sri Lankan study found that Total Dissolved Solids (TDS) are positively correlated with the occurrence of chronic kidney disease (CKD). Evaluating solid matter in water as a means to assess the quality and safety of water is therefore imperative. This blog breaks down the three Ts that underpin the analysis of solid matter in water. 

What are Solids in Water?

Solid matter in water refers to any particulate material that is present in a water body and is not dissolved. These solid particles can vary in size, composition, and origin. They can include both organic and inorganic materials. According to the Environmental Protection Agency (EPA), total solids in water consist of dissolved solids plus suspended and settleable solids. Suspended Solids are solid particles that are suspended in a water body and can remain in suspension for a significant amount of time. They include a range of materials such as soil particles, silt, clay, organic matter, and even microorganisms and give water a cloudy or turbid appearance. Settleable solids are larger solid particles that can settle to the bottom of a water body under the influence of gravity. Let us now break down turbidity, suspended solids, dissolved solids, and the ratios that are related to them.

What is Water Turbidity?

Water turbidity refers to the visual clarity of the water and is influenced by the solid matter that is present in it. The primary purpose of monitoring turbidity is to assess water clarity. Water with high turbidity exhibits opacity and is commonly referred to as cloudy or murky. This characteristic haziness in highly turbid water is closely linked to the abundant presence of particles dispersed throughout the water medium.

Turbidity can be analyzed using two distinct methods: nephelometry and turbidimetry.  

EPA Recommended Calculation of Turbidity and Nephelometry

In both approaches, the light of a predefined intensity is passed through the water and subsequently registered. Nephelometry analyzes the degree of light scattering, while turbidimetry precisely calculates the extent of light attenuation. The outcomes derived from these methodologies are now standardized and expressed in units denominated as Nephelometric Turbidity Units (NTU) or Formazin Nephelometric Units (FNU). To be more precise, NTU serves as the metric frequently employed to represent turbidity measurements taken using white light, measured at a 90-degree detection angle (in accordance with EPA 180.1 guidelines), while FNU finds application when measurements are taken using near-infrared light at 860 nm, also at a 90-degree detection angle (per ISO 7027 standards).

What is TDS and How is it Calculated?

Total Dissolved Solids (TDS) refer to the total content of all inorganic and organic substances present in a liquid solution, typically water, that are capable of passing through a 2-micron filter. TDS includes minerals, salts, metals, ions, and other dissolved substances. It is usually expressed in milligrams per liter (mg/L) or parts per million (ppm).

TDS is calculated using various methods, including evaporation and gravimetric method, conductivity method, and refractometry method. These methods use electrical conductivity to estimate TDS. They measure the conductivity of a solution and apply a conversion factor to calculate TDS. However, it’s important to note that this conversion factor can vary depending on the composition of the dissolved substances.

In a laboratory setting, TDS can be analyzed using advanced techniques such as ion chromatography, mass spectrometry, and other analytical methods. These methods provide precise measurements and can identify specific dissolved substances.

When using any method to calculate TDS, it’s crucial to consider factors that might affect the accuracy, such as temperature, the composition of dissolved substances, and the calibration of instruments. TDS measurements provide valuable information about water quality, particularly in terms of its suitability for various purposes, including drinking, industrial processes, and environmental monitoring.

What is TSS and How is it Calculated?

Total Suspended Solids (TSS) refer to the concentration of solid particles that are suspended in water and can be trapped by a filter. These particles can include silt, clay, organic matter, plankton, and other particles that are not dissolved in the water but are instead floating or suspended.

TSS is typically measured in milligrams per liter (mg/L) or parts per million (ppm) and is an important parameter in water quality assessment, as it can impact the clarity of water, light penetration, and overall aquatic ecosystem health.

There are various methods to calculate TSS, including gravimetric method and direct measurement. In a laboratory, TSS can be determined using advanced techniques such as centrifugation, where the solids are separated from the water by spinning the sample at high speeds, or by using particle counters that can provide detailed information about the size distribution of suspended particles. Monitoring TSS is crucial for understanding the health of aquatic ecosystems, assessing the efficiency of wastewater treatment processes, and ensuring water quality for various uses.

Optimizing Water Quality Analysis with LIMS for Water & Wastewater Testing

A Laboratory Information Management System (LIMS) plays a pivotal role in enhancing water quality analysis by automating sample tracking, data management, and reporting of test results to clients and regulatory agencies. A LIMS for water and wastewater testing streamlines sample registration and maintains a chain of custody, ensuring accurate and efficient record-keeping and staff accountability for each stage of analysis. A LIMS for water & wastewater testingcan automate calculations and apply standardized methods for solid analysis, ensuring consistent and reliable results. A LIMS for water and wastewater testing can also integrate with multiple analytical instruments, facilitating centralized management of test results obtained from all instruments. Furthermore, it facilitates real-time data access, enabling researchers to make informed decisions and expedite regulatory compliance in the assessment of solid matter in water. 


The Three Ts—Turbidity, Total Dissolved Solids (TDS), and Total Suspended Solids (TSS) paint a clear picture of the safety of water for both aquatic and animal (including human) life. This blog delineates what the three Ts represent and how they are calculated. Labs that analyze solid matter in water are essential in safeguarding a healthy ecosystem. Such labs can leverage a cloud-hosted LIMS for water and wastewater testing to optimize efficiency and increase productivity.


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