Operator terms · Wastewater
What is TSS (total suspended solids)?
TSS, total suspended solids, is the weight of solid particles suspended in water, measured in mg/L. In wastewater it shows how much solid material is present before and after treatment. Removing suspended solids is a main goal of clarifiers, so falling TSS means treatment is working.
Last reviewed 2026-08-03
Where it is removed
Clarifiers and filters take out suspended solids by settling and straining. Operators compare influent and effluent TSS to see how much the plant removed.
TSS and BOD together
Suspended solids often carry organic matter, so TSS and BOD tend to rise and fall together. Both are common permit limits on the treated effluent.
Common questions
- What units is TSS in?
- Milligrams per liter, mg/L.
- How is TSS removed?
- Mostly by settling in clarifiers and by filtration.
- Is TSS a permit limit?
- Often, yes, along with BOD, on the discharged effluent.