Pehme vesi on vesi, mille mineraalainete sisaldus on tavaliselt väiksem kui 1 GPG (grains per gallon - terad galloni kohta) ja sellest väärtusest ületavat vett peetakse karedaks, kuna selles on kõrgem mineraalainete sisaldus.
Soft water is water with a mineral content that is typically less than 1 GPG (grains per gallon), and water above this value is considered hard because it has a higher mineral content.
