What is 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 cations like calcium, magnesium, potassium, and sodium, as well as anions like carbonates, nitrates, bicarbonates, chlorides and sulphates. Cations are positively charged ions, whereas anions are negatively charged ions.

Aquaread Total Dissolved Solids Sensor

If you’re looking to discover an easy way to test for total dissolved solids, our TDS meter is an efficient and reliable solution.

Aquaread’s TDS measurement is calculated within our software using the electrical conductivity (EC) measurement and temperature in a simple equation.

The output for the TDS sensor is in parts per million (PPM) or mg/L.

A TDS value gives a measurement of the amount of organic and inorganic substances dissolved within the water.

Key Features

Calculated parameter that’s always included on every Aquaprobe and Aquasonde.
Also included in the AquaPlus optical dissolved oxygen sensor.
Uses the corrosion-resistant gold-coated stainless steel EC sensor.
Measurement range 0 – 100,000 mg/L.
Resolution 2 auto ranging scales: 0 – 9999mg/L, 10.00 – 100.00 mg/L.
Accuracy of 1% of reading.
Requires no calibration – this is taken care of when you calibrate the EC sensor

Our total dissolved solids sensors come as standard on many of our probes — below are some examples. To see all of the probes that feature TDS sensor, please visit the Products section.

AquaPlus

Portable, GPS AquaPlus Optical DO/EC system

AP-2000

Advanced portable multi-parameter Aquaprobe.

Aquasonde-5000

The Aquasonde-5000 has 4 spare ports. They can house any combination of ISE and Optical sensors.

Always included

The TDS sensor is included on every Aquaprobe and Aquasonde, it is also included in the AquaPlus optical dissolved oxygen sensor.

More on TDS testing

The various minerals discussed above 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.

How to use the EC sensor

The probe is simply 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 EC of the water. Pure H2O has almost zero conductivity. TDS water testing on Aquaread’s Aquaprobes are calculated from EC and temperature values.

When to use the electrical conductivity sensor

TDS test equipment can be used to build up an understanding of the typical range of TDS for a particular water body. This can be used as a baseline for regular monitoring and, if there is a significant change in TDS, this could be an indicator of a discharge or other pollutant entering the water. TDS varies with the water source, i.e. ground water, agricultural runoff, municipal wastewater, rainfall. A change in water EC and TDS can indicate ground water seepage or a sewage leak for example.