Zone

Characterization of water quality

1

Alkaline earths (Ca²⁺ + Mg²⁺) exceed alkalies (Na⁺ + K⁺)

2

Alkalies exceed alkaline earths

3

Weak acids ${\text{HCO}}_3^{-}+{\text{CO}}_3^{2-}$ exceed strong acid ${\text{Cl}}^{-}+{\text{SO}}_4^{2-}$

4

Strong acids exceed weak acids

5

Carbonate hardness (secondary alkalinity) exceeds 50% that is by alkaline earths and weak acids

6

Non-carbonate hardness (secondary salinity) exceeds 50%

7

Non-carbonate alkali (primary salinity) exceeds 50%

8

Carbonate alkali (primary alkalinity) exceeds 50%

9

Mixed type (transition zone)-No cation-anion pair exceeds 50%