Total Suspended Solids (TSS) / Turbidity (Water Clarity)

Total Suspended Solids (TSS)

A very close relationship exists between the total suspended solids (TSS) present in an ecosystem and water clarity / turbidity. Suspended solids at high concentrations reduce water clarity, increase water temperatures, cause a decrease in photosyntehesis, and consequently reduce dissolved oxygen.


  1. A wide mouth jar is used to collect water. Ensure that the turbidity of the water is not influenced by your movement.
  2. Weigh a dried filter paper. Ensure that the paper has been kept in the dehydrator and weighed immediately. Tongs are to be used in working with the filter paper.
  3. Filter 250 mL of freshwater from your samples at each site. The filtered water may be collected to be used in the TDS analysis.
  4. Place the wet filter paper in an evaporating basin and put it in the incubator.
  5. When the filter paper is completely dry, reweigh it immediately after removal from the incubator. Your first recorded weights are the most accurate. You will notice the paper begin to rehydrate immediately and alter your results.
  6. The change in weight (weight of filter paper after - weight of filter paper before) is the weight of the TSS in 250 mL of sample water. Use the following table and formula to calculate TSS.

TSS = [Increase in weight (g) / Volume (mL)] X [1000 mg / 1 g] X [1000 mL / 1 L] = ? mg/L (ppm)

Calculating TSS

Final Mass of Filter Paper (g)        
Initial Mass of Filter Paper (g)        
TSS / 250 mL (=final-initial)        
TSS (ppm) (use formula above)        
Average TDS (ppm)  

Turbidity / Water Clarity

Turbidity or water clarity is a measure of the relative clarity of water. The greater the clarity, the less turbid the water. Turbidity is greatly influenced by the amount of suspended solids (TSS) in the water. Suspended solids reduce the transmission of light and reduce the rate of photosynthesis. Suspended solids usually include clays, silts, plankton and industrial and domestic wastes. Turbidity is significantly influenced by human activity. Soil erosion, waste discharge, urban runoff, algal growth and animal activity in the freshwater environment can all influence water clarity. Suspended solids absorb heat from sunlight and also reflect/block out sunlight. The increase in temperature and reduction of light for photosynthesis contribute to lower levels of dissolved oxygen (DO) in the ecosystem.


There are two methods, each suited for a particular freshwater ecosystem.

  1. The sechhi disc method is based on a 20 cm black and white disc being lowered on a measuring tape until it disappears. The distance at which it disappears can then be used as an indicator of water clarity. The disc method is not practical in shallow waters.
  2. An effective method of determining water clarity is to fill a 1 Litre measuring cylinder with your water sample. Create a small toonie sized disc out of white flexible plastic that has alternating black and white quadrants. Attach this disc to the end of a wooden metre stick by a tack so that the coloured part of the disc is projected up the stick. Lower this end of the stick into your water sample until it is no longer visible. At the point that it is no longer visible, measure the length of the submerged metre stick. Record this measurement in millimetres on your data sheet. For water clarity in excess of the cylinders depth, record this depth as greater than the depth measured.