Total Dissolved Solids Sensor

What are total dissolved solids?

Total dissolved solids refers to the total concentration of substances, including inorganic salts and organic matter, dissolved in a given volume of water, which is expressed in units of mg per litre or parts per million. Common inorganic salts that are found in water are calcium, magnesium, potassium and sodium, which are all cations, and carbonates, nitrates, bicarbonates, chlorides and sulphates, which are all anions. Cations are positively charged ions, whereas anions are negatively charged ions.

These minerals originate from various sources, both natural and a result of human activity. The concentration and composition of TDS in natural waters is determined by the geology of the drainage basin, atmospheric precipitation and the water balance. Alterations in the concentration of total dissolved solids in natural waters is often the result of industrial effluent, changes to the water balance (i.e. increased water use or increased precipitation) or by saltwater intrusion.


Total dissolved solids are related to the purity of water and the suitability of water for drinking and irrigation. TDS is also important in aquatic ecosystems as organisms require the ingestion of certain minerals for bodily functions.

How to use a total dissolved solids meter

Before using a TDS meter it is important to read the instructions, as the TDS sensor contains sensitive electronic equipment. Generally the probe is inserted into the water to be tested and the reading is taken from the display screen. The TDS meter will measure all the anions and cations that are present in water by measuring the electric conductivity (EC) of the water. Pure H2O has almost zero conductivity. TDS water testing on Aquaread’s Aquaprobes are calculated from EC and temperature values.

Aquaread’s Total Dissolved Solids Testing Equipment

Aquaread’s Aquaprobes have a range of standard parameters that can be added to with optional parameters. Two of these standard parameters are electric conductivity and temperature. Using these measurements, the Aquameter, that is used with the Aquaprobes, automatically calculates the total dissolved solids value and displays it on the screen. Aquaread’s TDS testing equipment is capable of measuring TDS in the range of 0 – 100,000 mg/l or PPM.


The AP-2000 is designed to be portable and easy to carry from site to site. The Aquaprobe logs the GPS coordinate of readings to simplify the mapping process. If long term monitoring would be more efficient, the AP-7000 has been created for the ultimate in unmanned water testing.


Get into monitoring with Aquaread

If you would like any more information about TDS meters and other total dissolved solids testing equipment, or water quality monitoring in general, please contact us. Click here to see our product range.