Definition
Water's resistance to pH change; the combined effect of bicarbonate (HCO₃⁻), carbonate (CO₃²⁻) and hydroxide (OH⁻) ions, reported as mg/L CaCO₃.
Detailed Explanation
Alkalinity is the water's capacity to neutralise acid (its buffering capacity); it comes from bicarbonate (HCO₃⁻), carbonate (CO₃²⁻) and hydroxide (OH⁻) ions and is reported as mg/L CaCO₃. In mains water most of the alkalinity is bicarbonate. It is measured by titrating the sample with acid to a set pH (about 4.5 for total alkalinity).
Why It Matters
During boiling, bicarbonate loses carbon dioxide and turns into carbonate; with calcium present this accelerates calcium-carbonate (scale) formation. Alkaline salts concentrating in the tank can also increase the foaming tendency. Alkalinity is therefore used together with hardness to assess scaling and foaming risk.
Engineering Note
Alkalinity enters the Langelier Saturation Index (LSI) calculation together with pH, calcium hardness, TDS and temperature: a positive LSI indicates a scaling tendency, a negative LSI a corrosion tendency. LSI depends on temperature; a water that looks balanced when cold can be scale-forming at boiling temperature. Where alkalinity is high, softening or RO pre-treatment and the drain setting are evaluated against the manufacturer's feedwater requirements.
How Nem Kontrol Teknolojileri Applies It
As Neptronic's authorised distributor in Türkiye, Nem Kontrol Teknolojileri asks the customer for a recent water analysis from an accredited laboratory when selecting a steam humidifier and compares the values with Neptronic's feedwater requirements. The resistive Neptronic SKE4 runs on any water, RO and DI included; water quality only affects maintenance frequency. Pre-treatment systems are designed and installed by specialist water-treatment companies.
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