The Role of TSS Testing in Water & Wastewater Treatment

Home
The Role of TSS Testing in Water & Wastewater Treatment

02/21/2025 Technical Article

Learn about the process, tools & tips for TSS Testing

What is TSS testing?

TSS (Total Suspended Solids) testing is the process of determining the quantity of solids in samples taken from various water sources. This kind of testing is common in water, wastewater, industrial, environmental and dozens of other industries, but we’ll be focusing on water and wastewater testing.

Understanding TSS testing is crucial for maintaining high-quality water for your customers and safe wastewater effluent.

How is it performed?

TSS can be monitored in-line at various locations in the treatment process or tested in the laboratory from grab samples.

In the lab, a professional will follow EPA Method 160.2 or Standard Method 2540D by preparing the filter paper, filtering flask, vacuum pump and sample to ensure no contaminants impact testing parameters. When determining weight differences as little as 0.5mg (.0005g), keeping a clean and organized workstation while following the testing parameter guidelines is essential. Check the ‘Industry Tips for TSS Testing’ section for testing parameters and safety specifics.

This video by Rocker Scientific showcases the process and equipment needed to perform a standard TSS test in a lab environment.

How does TSS impact water quality?

Water treatment has two main objectives: the removal of particles and organics, and water and wastewater disinfection. Monitoring suspended solids helps inform treatment processes. For example, changes in solids levels in source water entering a drinking water plant will change how the water is treated and monitoring TSS at the outlet of a wastewater plant indicates the efficacy of the treatment

TSS testing provides insights into the overall water quality by assessing pollution levels, monitoring potentially harmful substances and quantifying the amount of solids present in water and wastewater.

Samples come from a large variety of sources including bodies of water like lakes, rivers and aquafers, or at the treatment plant along various primary and secondary settling and disinfection tanks. Influent and effluent are tested regularly, ensuring the plant operates effectively and captures TSS before the wastewater exits into the environment. Primary and secondary treatment samples are taken in most wastewater plants for the same reason.

TSS Levels

High TSS levels can be a sign of contamination, and taking repeated samples to discover the source is an essential step in wastewater treatment and crisis mitigation. Suspended solids can carry pollutants, nutrients and pathogens that are detrimental and dangerous for customers and the environment.

Higher or lower-than-expected TSS results enable a team to make informed decisions about the treatment processes and do more specific testing to identify substances or areas of contamination.

Reference Materials

Do you need more specifics about your TSS testing application? The Standard Methods for the Examination of Water and Wastewater is a comprehensive resource for processes, including TSS testing.

See below for the commonly used formula for determining mgTSS/L. ref. Standard Methods 2540-D.

total suspended solids calulcation formula

Industry tips for TSS testing

Several best practices should be followed to ensure accurate results when performing Total Suspended Solids (TSS) testing.

Balance & Weighing

Maintain and ensure your balance is accurate. Use an analytical balance that is verified monthly to meet accuracy requirements. It’s also important to use a Class 1 or 2 Standard weight that has been verified by an external metrology company within the last five years.

When testing for micrograms of material, it’s important to use enough sample to get an accurate reading of your sample body. Failing to use enough sample can force unnecessary repeated tests when trying to meet the minimum threshold value (0.0005g).

Filter

The glass-fiber filter and filtration manifold must meet the method criteria for the process test while ensuring the filter frit is clear of clogs or gunk build-up. Regarding the filter, it’s important to dry and weigh the filter after it’s cooled in your desiccator. Confirm the accuracy of the filter by testing with a deionized water sample when necessary.

Pre-dried and weighed filters can avoid this step, but ensure the filter includes a weight certificate before beginning your testing process. Handle your filters carefully, as they can easily tear or become compromised, leading to a necessary test repeat.

Seat the filter in the funnel of the crucible with a light squirt of deionized water. This will keep it from moving or potentially losing any sample.

Drying

Dry samples at a constant 103–105°C. If your oven falls out of this range for any reason during the drying process, adjust and redry or retest as needed. A sample heated below 103°C will need to be brought back up to the correct range before testing, while a sample heated above 105°C will need to be discarded and a new test developed.

If the sample is not dry within 8 hours, you’ll need to do a constant weight check by repeating the drying, cooling and weighing cycle until changes in the sample are within .0005g or 4%, whichever amount is less. At this scale, the humidity or heat interacting with the aluminum pans can skew the results, so it’s important to re-weigh them until they are consistent.

Finally, be sure to record everything! Time in, time out, initials, outside and inside temperature and oven temperature are all important to keep track of when recording TSS. You can keep samples in a refrigerator for up to 7 days.

Are you ready for TSS testing?

This important practice ensures that drinking water quality and effluent is being maintained in water and wastewater. Knowing how to use TSS results and how they relate to water quality and investigations is an important task for any water and wastewater professional.

Best practices include using calibrated balances, properly handling filters, and drying samples at precise temperatures. Accurate TSS monitoring informs treatment processes, helping operators maintain effective water quality and compliance with environmental standards.