Electrical conductance, PPM (parts per million), specific resistance
The following water ingredients can through one Resistance, conductivity, conductance or ppm (parts per million) measurement not to be measured:
- Drug residues, antibiotic residues, pesticides, solvents, chlorine, hormones, endocrine-active substances, etc
- Bacteria, microorganisms, parasites, viruses, fungi, spores
- Lead, cadmium, nickel, arsenic, chromium, aluminum, radioactive substances (uranium, enriched uranium, plutonium (the concentrations are too low!)
- Nitrate, nitrite, ammonium, ammonia
However, it is precisely these pollutants that, according to reverse osmosis system sellers or osmosis water fans, should be quickly detected through conductivity, conductivity or ppm measurements.
See also > The trick with electrolysis testing
Only nutritionally important mineral salts or minerals or ions (colloquially known as minerals) can be determined in water by measuring resistance or conductivity or ppm.
In addition, only the total, quantitative amount of mineral salts contained in the water is measured, not qualitatively.
The nutritionally important mineral salts in the water:
Calcium, magnesium, potassium, phosphate, sodium, chloride, selenium, sulfate, etc.
The basic mineral salts calcium, magnesium, potassium and sodium are particularly abundant in the body and ensure an alkaline pH value in the water.
Therefore, a conductivity measurement (or ohmic resistance, also ppm measurement) is not only absolutely unsuitable for analyzing pollutants in water, but is primarily used to mislead consumers.
See the article by ZDF WISO on YouTube about reverse osmosis water and systems.
Important information about the >Bioavailability of minerals can be read on this page.
Below, we have provided you with the detailed, physical definitions of the different terms to the best of our knowledge:
Electrical conductivity, specific resistance, electrical conductance, ohmic resistance
Basics:
Conductivity is a measure of the total ion concentration (in colloquial language also minerals or mineral salts) of a measurement solution or, in our case, water.
Pure water has very low electrical conductivity. If you add substances to the water that release freely mobile, electrically generated ions (electrolytes), such as salts, acids or alkalis, then the conductivity increases depending on the type and concentration of these ions as well as the temperature (mobility of the ions).
The more salts (mineral salts, colloquially: minerals), acids or bases are present in the measurement solution, the higher the conductivity or conductivity.
Water and wastewater mainly contain ions (cations and anions) from dissolved salts.
The conductivity therefore provides information about the salt load and not the pollutant load in the wastewater or drinking water.
The electrical conductivity has the unit:
µS/cm (microSiemens per centimeter) or S/cm (Siemens per centimeter)
Ions (cations and anions)
How conductivity arises in liquids
Electrical conductivity in liquids occurs when salts, acids and alkalis break down into positively charged cations and negatively charged anions. Common salt (NaCl), for example, breaks down in water to form sodium ions (Na+) and chloride ions (Cl-).
Absolutely pure water has a very low conductivity because around every billionth water molecule (H2O) breaks down into the ions H+ and OH-.
Reverse osmosis water, also called osmosis water, can be between 5 µS/cm for osmosis systems with a tank and up to 50 µS/cm for direct-flow reverse osmosis systems (flow systems without a tank).
Measurement of conductivity
Electrical conductivity is measured by measuring resistance. In the simplest case, the measuring cell consists of two metallic electrodes between which an alternating voltage is applied. The more ions the sample solution contains, the greater the current flowing between the electrodes. The conductivity is then calculated using Ohm's law. The unit of electrical conductivity is S/cm.
Parts Per Million (PPM)
The English expression parts per million (ppm) is used in science and technology for one millionth of a million, just as percent (%) is used for one hundredth of a million.
The ppm values are determined using a TDS measuring device, a TDS meter:
TDS measuring devices, TDS meters
TDS is an abbreviation for the English term 'total dissolved solids': Total dissolved solids.
The TDS value in ppm (parts per million) or converted units (1 ppm is approximately one mg per liter) indicates the concentration of dissolved substances in water. Since the TDS value results from the conductivity (EC) determination of the water, dissolved substances refer to salt-like substances that contribute to the conductivity through the ions present in the water.
TDS meters are also used to determine salinity (salinity in mg/L) by applying appropriate conversion factors.
The commercially available TDS meters are therefore usually combination devices with an option to determine conductivity and other water parameters (pH value).
Further general information on the topic can be found at > TDS value on www.internetchemie.info
You can find out more about minerals and mineral salts in water at > this page.
