Compared
TSS vs. turbidity
TSS and turbidity both describe solids in water but measure them differently. TSS (total suspended solids) is the actual weight of suspended solids, in mg/L, from a lab filter test. Turbidity is how cloudy the water looks as light scatters off particles, in NTU. They tend to rise and fall together.
Last reviewed 2026-08-04
| TSS | Turbidity | |
|---|---|---|
| Measures | Weight of suspended solids | Cloudiness from scattered light |
| Units | mg/L | NTU |
| How | Filter and weigh in a lab | A meter reads light scatter |
| Speed | Slower lab test | Fast, near-instant |
The bottom line
TSS is the measured weight of solids; turbidity is how cloudy the water looks. They track together but are not the same number.
Common questions
- Are TSS and turbidity the same?
- No. TSS is a weight; turbidity is a cloudiness reading. They usually rise and fall together.
- Which is faster to check?
- Turbidity, since a meter reads it almost instantly.
- What units are they in?
- TSS is in mg/L; turbidity is in NTU.