Corrosion inhibitors:

Phosphates, silicates or organic inhibitors prevent corrosion in pipes and systems.

Precipitants:

Aluminum or iron (III) salts flocculate particles and reduce deposits

pH regulators:

Acids (e.g. sulphuric acid) or bases (e.g. caustic soda) regulate the pH value of the water to minimize corrosion.

Biocides:

Chlorine compounds or other disinfectants eliminate microbial growth in open circuits.

Softeners:

Ion exchange resins remove calcium and magnesium ions from hard water to prevent limescale deposits.

Filtration:

Physical processes such as sand, activated carbon or membrane filters remove suspended solids, particles or organic residues from the water.

Reverse osmosis:

Semi-permeable membranes are used to remove almost all salts, microorganisms and organic substances dissolved in the water, leaving almost pure water. In certain applications, minerals (e.g. calcium) can then be added to the water, for example when it comes into contact with people or food.