The Water Dictionary

Monchique

Alkaline Water

StillSerra de Monchique, Portugal

Monchique is a natural mineral water from the Serra de Monchique, a small igneous mountain range in the Algarve, southern Portugal. The source is associated with alkaline syenite rock, which imparts the water’s unusual chemistry. The brand is commercially bottled in the municipality of Monchique.


Mineral composition

mg/L
Calcium1
Magnesium0
Sodium105
Sulfate59
Chloride40
Bicarbonate106
Hardness: 3 as CaCO₃Alkalinity: 87 as CaCO₃

Compositions can vary by season and source. Read our methodology.

Mineral character

Monchique has an exceptional profile. Calcium is 1.1 mg/L, magnesium 0.05 mg/L, sodium 105 mg/L, sulphate 59 mg/L, chloride 39.6 mg/L, and bicarbonate 106 mg/L. Hardness is 3 mg/L as CaCO₃ — among the lowest in the TWD database. The defining characteristic is the naturally alkaline pH of 9.5, the highest recorded among naturally occurring commercial mineral waters. The low calcium and magnesium combined with elevated sodium reflect the alkaline igneous geology; the pH 9.5 is produced by sodium bicarbonate and sodium hydroxide chemistry in the syenite aquifer. This is a distinctive and unusual geological profile.


Use-case suitability


Where to buy

PT

Lidl PT, Auchan PT

€0.20 per litre

Available in Portugal and through specialist importers. As of March 2026.