What are total dissolved solids?
The total dissolved solids test measures the amount of particles that
are dissolved in the water. It may include all suspended solids that
may or may not pass through a filter.
What factors influence the amount of total dissolved solids in water?
1. Some dissolved solids come from organic sources such as leaves, silt,
plankton, and industrial waste and sewage. Other sources come from runoff
from urban areas, road salts used on street during the winter, and fertilizers
and pesticides used on lawns and farms.
2. Some dissolved solids come from inorganic materials such as rocks
and air that may contain calcium bicarbonate, nitrogen, iron phosphorous,
sulfur, and other minerals. Many of these materials form salts, which
are compounds that contain both a metal and a nonmetal. Salts usually
dissolve in water forming ions. Ions are particles that have a positive
or negative charge.
3. Since rain water contributes to most of the water in a watershed,
it contributes to the amount of TDS in a watershed. Rain water is almost
pure with less than 10 mg/L of TDS.
What is the optimal amount of total dissolved solids in water for
most aquatic plants and animals?
1. A constant level of minerals in the water is necessary for aquatic
life. Changes in the amounts of dissolved solids can be harmful because
the density of total dissolved solids determines the flow of water in
and out of an organisms cells. Concentration of total dissolved
solids that are too high or too low may limit the growth and may lead
to the death of many aquatic organisms.
2. Drinking water may have a TDS reading of 25-250 mg/L. Drinking water
should not exceed 500 mg/L TDS.
3. Distilled water will have a TDS reading that will range from 0.5-1.5
mg/L.
4. The amount of TDS ranges from 100-20,000 mg/L in rivers and may be
higher in groundwater.
5. Seawater may contain 35,00 mg/L of TDS.
6. Lakes and streams may have a TDS reading of 50-250 mg/L.
What factors are affected by your amount of total dissolved solids
in your watershed?
1. A constant level of minerals in the water is necessary for aquatic
life. Changes in the amounts of dissolved solids can be harmful because
the density of total dissolved solids determines the flow of water in
and out of an organisms cells. Many of these dissolved solids
contain chemicals, such as nitrogen, phosphorous, and sulfur, which
are the building blocks of molecules for life.
2. Concentration of total dissolved solids that are too high or too
low may limit the growth and may lead to the death of many aquatic organisms.
3. High concentrations of total dissolved solids may reduce water clarity,
which contributes to a decrease in photosynthesis and lead to an increase
in water temperature. Many aquatic organisms cannot survive in high
temperatures.
4. It is possible for dissolved ions to affect the pH of the body of
water, which in turn may influence the overall health of many aquatic
species.
5. If TDS levels are high, especially due to dissolved salts, many forms
of aquatic life are affected. The salts act to dehydrate the skin of
animals.
6. High TDS concentrations may add a laxative effect to the water or
cause the water to have an unpleasant mineral taste.