Total Water Hardness

Knowing About the Water

Total Water Hardness 

Although much has been written over the past 75 years about water hardness, no universal definition exists of what constitutes various levels of Water Hardness. Water Hardness is measured chemically by the amount of Calcium Bicarbonate and Magnesium Bicarbonate contains in the water sample. Together, the sum of these two represents what is termed the “Total Hardness” or TH. Technically this measurement is called Temporary Hardness, as these carbonates can break down under elevated water temperatures. 
The common unit of measuring Water Hardness is grain per U.S. gallon (gpg). The more scientific measurement is in part per million (ppm), or what is generally considered the equivalent metric measure of milligrams per liter (mg/l). It takes 17.1 ppm (mg/l) to equal one U.S. gpg. Usually water testing above three grains (52ppm) per gallon is labeled “HARD”. However, the level of Hardness is very important especially in boiler feed water. To establish a set of Hardness levels, the Water Quality Association (WQA) and the American Society of Agricultural engineers jointly adopted Standard S-339, which brackets Water Hardness categories. 


Here are some problems directly connected with Hard Water: Consumes much more soap and makes cleaning more difficult, soap scum and lime scum in wash basins and toilet bowl; ring around bathtub; leaves hair looking duller after shampooing; dingy yellow collar in white laundry goods; whitish scale deposits in pipes, water heater and tea kettles. There also are some scientific studies relating Hard Water with human health such as hardening of the arteries.