We cannot see pH or other kinds of water qualities, but we can observe TSS directly. Suspended solids cause the water to be milky or muddy looking due to the light scattering from very small particles in the water. Sometimes it is mixed with color, but colored waters can also be clear. Normally, we notice suspended solids before we notice anything else.
Polluted waters are commonly turbid and improvement is usually marked by greater clarity.
Of course, good and useful waters may be turbid, and many clean rivers are never clear because they contain fine suspended minerals that never settle. To determine total suspended solids, weigh a piece of filter paper as accurately as possible. Filter a one liter sample of water through the weight filter paper. Allow the filter paper to dry completely. Placing a lamp above the filter paper may help the drying process, but take care in not getting the filter paper too hot.