K (m/day)

Qualification

Behaviour

K < 10⁻²

Very low

Waterproof

K_h > K_V

(K_h 10 to 20 times greater)

10⁻² < K < 1

Short

Poor aquifer

1 < K < 10

Half

Good aquifers

10 < K < 100

High

K > 100

Very high