Water Electrical Conductivity
The electrical conductivity of water measures its ability to conduct current; it depends on the amount of dissolved salts and is expressed in µS/cm.
Pure water barely conducts electricity. What makes it conductive are the dissolved ions: calcium, magnesium, sodium, potassium, bicarbonates, chlorides or sulphates. The more ions, the higher the conductivity. It is measured with a conductivity meter and expressed in microsiemens or millisiemens per centimetre (µS/cm, mS/cm), normally referred to 25 °C, because it increases with temperature. It is a quick measure of total mineralisation, but it does not say which ions are present: two waters with the same conductivity can have a different hardness.
In cleaning it has several uses. Highly mineralised water leaves more residue when it dries, which results in films and spots on tableware and glassware; that is why the final rinse water in some processes is demineralised. In CIP systems and industrial dishwashers, the conductivity of the solution is used to control the detergent concentration: adding product increases the conductivity, and dosing equipment can be regulated with that reading. It is also used to detect the change from rinse water to product, or from product to water, in circuits. The conductivity of drinking water is one of the parameters covered by Spanish Royal Decree 3/2023.
Instaquim products designed for high-conductivity water, according to their technical data sheet:
- Deterdry (pH 2.0; 0.1–1 g/l at 65–80 °C): final rinse additive for dishwashers, «specially designed for water with high conductivity», with drying and antifoaming agents.
- eqo Abrillantador (pH 2.0; 0.1–0.8 g/l at 65–80 °C): final rinse additive for tableware and glassware in water with high conductivity.