Water hardness is caused almost entirely be calcium and magnesium ions. Other di- and tri-valent metals have a similar effect, but are usually not present in high enough concentration in potable waters to cause problems. Hardness increases soap consumption in laundries and causes scale in boilers.
|Method||Range (mg/L)||Steps (mg/L)||Approx. Number of Tests|
|Test Strip||0-425||0, 25, 50, 120, 250, 425||50|
|(0-25gpg)||(0,1.5, 3, 7, 15, 25 gpg)|
|1 gpg = 17.1 - mg/L or 17.1 ppm|
gpg - grains per gallon