What is Total Suspended Solids (TSS)?

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Those looking to better understand tap water quality and chemistry, may yet be unfamiliar with total suspended solids (TSS). However, TSS is a common water contamination issue that affects thousands of people and water systems across the country.

So, what is TSS, and is it something people should be concerned about? Or is it a problem only in specific water sources? This short guide covers everything one needs to know, offering a total suspended solids definition and advice on how to produce a total suspended solids calculation. 

What are Total Suspended Solids?

TSS stands for total suspended solids, and refers to waterborne particles that exceed 2 microns in size. Any particle that is smaller than 2 microns, on the other hand, is considered a total dissolved solid (TDS). The majority of total suspended solids comprise of inorganic materials; however, algae and bacteria may also be considered TSS. 

TSS could be anything that floats or “suspends” in water, including sand, sediment, and plankton. When certain water sources are contaminated with decaying plants or animals, the organic particles released into the water are usually suspended solids. While some sediment will settle at the bottom of a water source, other TSS will float on water’s surface or remain suspended somewhere in between. TSS affects water’s clarity, so the higher a water source’s TSS content, the less clear it will be. 

Total Suspended Solids Calculation

You can accurately calculate total suspended solids in wastewater by using a TSS sensor or monitor. These devices measure water in the region of 1,000 mg/L – 8% solids, indicating the presence of suspended solids in water. 

Note that a TSS sensor is different from a TDS meter, which measures for dissolved solids in water, not suspended solids.   

For more accurate results, it is best to conduct a laboratory test, which will use the total suspended solids EPA method to provide a thorough analysis of total suspended solids in drinking water. 

What Are the Most Common Suspended Solids?

Bacteria

Bacteria is most typically found in well water sources. Legionella and Coliforms are common types of waterborne bacteria. Certain types of bacteria pose a risk of illness when consumed, while other types of bacteria indicate that illness-causing bacteria may be present in your water. 

Clay

Again, clay is a common well water contaminant, particularly colloidal clay. This type of TSS may give water a particularly cloudy appearance. While clay may not be harmful to health when consumed in small amounts, it may affect water taste and smell and is notoriously difficult to remove. 

Gravel

Gravel is another type of sediment that gives water a dull, murky or cloudy appearance. Do not expect to see large clumps of gravel in drinking water, though. Each gravel particle is usually too small for the human eye to see. Usually, being a heavier particle, gravel will settle at the bottom of a body of water. 

Sand

Sand in water is particularly a problem in areas with a sandier soil composition. Again, it is an issue one is most likely to experience if they are a well owner, and the simplest solution is to filter it out with a sediment filter. Sand is another heavier particle that usually settles at the bottom of a body of water. 

Silt

Finally, silt particles are typically between the size of sand and clay, and can be found in rivers, lakes and soil. While silt is not usually dangerous, it can be aesthetically damaging, and may affect the appearance of water. 

What Increases Total Suspended Solids in Water?

Erosion & Runoff

Increased erosion of banks of rivers and streams can increase the TSS level in water. The suspended particles released from dirt and soil can settle out across water and give it a murky appearance. Runoff — when water flows through eroding soil — may also produce similar results. 

Human Pollution

Human activity is responsible for TSS levels in water sources across the U.S. Dissolved pollutants like pathogens and heavy metals can attach onto suspended water particles, decreasing water quality. Common human pollution contaminants include pesticides, lead, bacteria, and mercury. 

Algae

Algae are found in both saltwater and freshwater sources. When these organisms die, organic material is released into the water, reducing water’s oxygen levels and contributing to TSS levels. 

Sediment Disruption

Heavier sediment, like sand and gravel, typically settles on the bottom or riverbeds and streams. If human or natural activity has disrupted sediment in a flowing body of water, however, this sediment may become suspended in water, increasing levels of TSS downstream. 

What Are the Effects of High TSS in Water?

High total suspended solids in drinking water or wastewater can have both environmental effects and effects on human health. 

When it comes to water quality, high TSS may decrease water’s natural dissolved oxygen levels and increase water temperature. This may prevent organisms living in the water, such as small fish, from being able to survive. TSS may also block sunlight, which may halt photosynthesis, decreasing the survival of plants and further decreasing water’s oxygen levels. 

Total suspended solids in drinking water may affect human health too, though it depends on what is being faced. Bacteria and algae, for instance, may cause gastrointestinal issues, while pollutants like metals could result in serious health effects or even death. Some common TSS, like sand and silt, may be unharmful to health but may cause aesthetic issues in the pipes, plumbing, fittings and water-based appliances around the home. 

Total Suspended Solids vs Turbidity

Turbidity and suspended solids are often used interchangeably, which can make it difficult to understand the difference between the two. However, they are not quite the same thing. 

Turbidity refers to water’s transparency and the more suspended solids water contains, the less transparent it will be. 

In short, turbidity is a measurement of how well light can pass through water, while TSS is a quantitative measurement of suspended particles in water.