A TDS meter — also called a total dissolved solids meter — measures the total concentration of dissolved solids (minerals, salts and metals) in water, displayed in parts per million (ppm) or mg/L. Sometimes called a TDS reader or PPM meter, it gives an instant digital readout of water purity — the higher the reading, the more dissolved solids are present. Pacific Sensor Tech supplies digital TDS, EC and PPM testers from pocket pens to benchtop instruments — calibrated Milwaukee meters for drinking water, reverse osmosis (RO), aquariums, hydroponics, pools and industrial process monitoring, with Australian stock and technical support.
TDS readings are shown in parts per million (ppm) or milligrams per litre (mg/L), and the two are equivalent: 1 ppm = 1 mg/L. A “ppm meter” and a “TDS meter” are the same instrument — both display the total dissolved solids in your water as a ppm value. Lower readings mean fewer dissolved solids: reverse-osmosis water is often below 50 ppm, while typical Australian tap water ranges from roughly 100 to 400 ppm. A steadily rising ppm reading is a reliable sign that a filter cartridge or RO membrane is due for replacement.
A TDS meter — also called a total dissolved solids meter — measures...
TDS Pocket Tester, Range: 0 to 999 ppm
Pocket TDS Pen, Range: 0 to 1990 ppm
Pocket TDS Pen, Range: 0 to 10000 ppm
Waterproof TDS Tester, Range: 0 to 1999 ppm (mg/L…
Waterproof TDS Tester, Range: 0 to 9990 ppm
Waterproof TDS Tester (0-2000 ppm)
Waterproof TDS Tester (0.00-20.00 mS/cm)
EC: 0 – 3999 uS/cm, TDS: 0 – 2000 ppm
EC: 0.00-20.00 mS/cm, TDS: 0.00-10.00 ppt
pH: 0.00 to 14.00 pH, EC: 0 3999 uS/cm, TDS: 0 to…
pH: 0.00 to 14.00 pH, EC: 20.00 mS/cm, TDS: 0 to …
Conductivity / TDS / NaCl / Temperature MAX Porta…
TDS tester, Range : 0 to 1990 mg/L (ppm)
Standard TDS tester – High range
Rang…
pH: 0.0 to 14.0 pH, EC: 0 to 1990 uS/cm, TDS: 0 t…
pH: 0.00 to 14.00 pH, EC: 0.00 to 6.00 mS/cm, TDS…
4-in-1 pH/EC/TDS/Temp. Combo Meter with ATC
4-in-1 pH/EC/TDS/Temp. Combo Meter with ATC
Conductivity / TDS / NaCl / Temperature Laborator…
pH/ ORP/ Conductivity/ TDS/ NaCl/ Temp
Need more than dissolved solids? A combination meter measures pH, EC (electrical conductivity) and TDS in a single device — ideal for hydroponics, aquariums, aquaculture and water treatment, where nutrient strength and acidity are tracked together. Milwaukee’s multi-parameter range runs from 3-in-1 handheld pH/EC/TDS testers through to professional benchtop instruments. For acidity alone see our pH meters; for conductivity and salinity see our conductivity & EC meters.
Every TDS meter actually measures the water’s electrical conductivity first, then converts it to a total-dissolved-solids figure in ppm using a conversion factor (typically 0.5 or 0.7). If you need the raw conductivity reading itself — for hydroponics, water treatment or lab work — see our full range of conductivity & EC meters.
A TDS meter measures the total concentration of dissolved solids — minerals, salts and metals — in water. It reads the water’s electrical conductivity and converts it to a value in parts per million (ppm) or mg/L. It’s used to check reverse-osmosis (RO) and filtration performance, monitor drinking water, and maintain the right conditions in aquariums, hydroponics, pools and aquaculture.
As a guide, the Australian Drinking Water Guidelines set an aesthetic (taste-based) value of 600 mg/L for total dissolved solids, with water generally regarded as good below this level. RO and filtered drinking water often reads under 50 ppm, while typical tap water sits around 100–400 ppm. A rising TDS reading is a useful sign a filter or RO membrane needs servicing.
Yes. Very low TDS water around 20 ppm is typical of reverse-osmosis or deionised water and is safe to drink — it simply contains very few dissolved minerals. Some people choose to remineralise RO water for taste. Note that a TDS meter measures dissolved solids only; it does not detect bacteria or specific contaminants.
Yes — a TDS meter is an inexpensive, fast way to confirm your filter or RO system is working, track water quality over time, and dial in conditions for hydroponics or aquariums. A measurable jump in TDS is often the first sign a cartridge or membrane needs replacing.
Both measure the same underlying property — the water’s electrical conductivity. A conductivity (EC) meter reports the raw conductivity in μS/cm or mS/cm, while a TDS meter applies a conversion factor to show that reading as total dissolved solids in ppm or mg/L. Many Milwaukee meters display both EC and TDS.
They describe the same measurement. TDS (total dissolved solids) is the quantity measured; ppm (parts per million) and mg/L (milligrams per litre) are the units it is displayed in, and 1 ppm = 1 mg/L. Most TDS meters read in ppm.
Calibrate against a known standard solution (for example 1413 μS/cm, or a 342/442 ppm TDS standard) at a stable temperature. Rinse the probe in distilled water, immerse it in the calibration solution, let the reading stabilise and adjust to the standard’s value. Recalibrate periodically and store the probe per the manufacturer’s instructions.
A combined EC/TDS meter (or a pH/EC/TDS model) is ideal, so you can track nutrient strength and dissolved solids together. Pocket testers such as the Milwaukee EC59 suit everyday checks, while benchtop models suit labs and quality control.
