The chemical characteristics of ground waters in Tenerife are studied, including all the different sources of perched waters from tunnels (galerias) wells and springs. The chemical determination includes: pH, electrical conductivity, calcium, sodium, magnesium, potassium, carbonates, bicarbonates, sulphates and chlorides. Determination of boron and flouride are also included.

Ground waters are classified according to the relationship between the electrical conductivity and the relative concentration of sodium, calcium and magnesium. The residual sodium carbonate is also studied. Considerations are also given with regard to the different geological aspects responsible for the accumulation of ground waters at high and low levels within the island.